Matter Matters - web.engr.oregonstate.eduweb.engr.oregonstate.edu/~rochefow/K-12 Outreach...

Matter MattersMatter MattersIntroduction

Overview:The goal of the unit is to teach students about the properties of matter and its different states. The students will learn definitions of the different states and be able to recognize all of them by their different properties. They will also learn how to identify a chemical reaction by phase changes and about matter that does not fit the accepted definitions of any of the three states.

Background:Everything is made of matter, and matter comes in three basic states: solid, liquid, and gas. Isaac Newton came up with definitions for the three states:

Solid—has definite shape and definite volumeLiquid—has definite volume but indefinite shapeGas—has indefinite shape and indefinite volume

These are known as the Newtonian definitions. A solid will keep its shape despite the shape of the container it is placed in, and it will always be the same size. A liquid will take the form of its container, but it always takes up the same amount of space. A gas will fill its container no matter how small or large. This allows for different levels of gas pressure.

The states of matter are dependent of the activity of the molecules that compose them. Molecules act differently at different temperatures. At cooler temperatures the molecules move slowly and are close together. This is a solid state of matter. As it heats up the molecules spread out and move faster, going through the liquid and the solid stages. When the molecules are close together the matter is much denser than when they are spread apart. For this reason, gases always float on top of liquids.

Many chemical reactions can be identified by a phase change. If a solid and a liquid are combined and a gas is released, a phase change occurred. If two liquids are mixed and a solid forms in them, then a phase change has occurred. There are many chemical reactions that include phase changes, such as baking soda and vinegar.

Some matter exists that cannot be classified by the Newtonian definitions of solid liquid and gas. These are called non-Newtonian fluids. These fluids display properties of more than one of the different states of matter (most commonly solid and liquid). They may be solid at some times but liquid under slightly different conditions (temperature is not altered). A common non-Newtonian fluid is corn starch mixed with water or Oobleck. It displays both solid and liquid properties.

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Matter Matters Matter Matters State Standards and Benchmarks

Oregon Standards for 3rd and 5th grade

Science- Collecting and Presenting Data.Oregon Common Curriculum Goal:

Conduct procedures to collect, organize, and display scientific data.

Benchmarks:Grade 3: Collect data from an investigation.Grade 5: Collect, organize, and summarize data from investigations.

Science- Physical Science Oregon Common Curriculum Goal:

Understanding structure and properties of matter

Benchmarks:Grade 3: Describe objects according to their physical properties.Grade 5: Identify substances, as they exist in different states of matter.

Science- Scientific InquiryOregon Common Curriculum Goal:

Formulate and express scientific questions or hypotheses to be investigated

Benchmarks:Grade 3: Make observations. Based on these observations, ask questions or form hypotheses, which can be explored through simple investigations.Grade 5: Make observations. Ask questions or form hypotheses based on those observations, which can be explored through scientific investigations

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Matter MattersMatter MattersVocabulary

Acid Base Borax Burn Carbon Dioxide Catalyst Chemical Crosslink Chemical Reaction CO2- Carbon Dioxide Color Change Combustion Condense Cornstarch Density Displacement Dissolve Endothermic Evaporate Exothermic Float Freeze Gas Gel Hydrophilic Hydrophobic Indicator Limiting Reagent Liquid Mass

Matter Melt Newtonian Non-Newtonian Fluid Oxygen Ph Phase Change Polymer Polyvinyl Alcohol Pressure Properties Reaction Saturate Shape Sink Sodium Acetate Sodium Borate Solid Soluble Sublimate Suction Super Saturated Solution Surface Tension Synthetic Temperature Temperature Change Vacuum Viscosity Volume

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Matter MattersMatter MattersLesson Index

Lesson:

Balloon Vacuum Demonstration

Candle and Rising Water Demonstration

Cartesian Diver Demonstration

Crushing Can Demonstration

Density Bottles

Dry Ice Demonstration

Egg in a Flask Demonstration

Floating Golf Ball Demonstration

Gel Beads

Hot/Cold

Inflating Bag Reaction

Liquid Nitrogen Demonstration

Measuring

Mentos Fountain Demonstration

Moving Gas

Page:

6

8

10

12

16

18

20

21

23

25

28

30

32

4

“Oobleck”

Silly Putty

Sink or Float Demonstration

Sodium Acetate Towers

Solid Stations

Solid, Liquid, Gas

Straws and Water

Synthetic Snot

Syringes and Gas Pressure

Water Whirlpools Demonstration

34

36

38

40

42

44

46

48

50

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Matter MattersMatter MattersBalloon Vacuum

Grades K-5 (with variations)

Overview:Students watch as a condensing gas creates a vacuum strong enough to pull a balloon inside a flask.

Time: 15-20 minutes (this was done as a station in the gas rotation)

Materials:Teaching/demo materials:

150 mL flask Water Hot plate Large Balloon

Setup:Set the hot plate and other materials at the station table. Either Pour about 1 cm of water into the bottom of the flask and begin to boil it on the hot plate before the students arrive or heat a small amount of water (a small amount works best because the temperature can change quickly) in the microwave, if you would like the balloon to inflate before it gets sucked into the flask..

Background:When water boils it is converted from liquid water into water vapor, which is a gas. Gas is much less dense than liquids, so the same number of molecules take up much more space in gas than in liquid form. If a gas is cooled to a liquid inside a sealed container it will create a vacuum because the liquid takes up less space than the gas. As nature attempts to create pressure equilibrium there will be inward force on the container since the pressure outside is much greater than that inside.

Activities/procedure:Heat a small amount of water in a flask (microwave works fine). The water does not need to be brought to a boil. Then put a balloon around the opening of the flask, creating a seal. When the flask is put on a hot plate, the balloon will inflate with water vapor. When the flask is submerged in room temperature water, the water in the flask will cool and the vapor will condense. This will create a vacuum and the balloon will be sucked inside the flask. Dipping the flask in room temperature water may help to speed the cooling process.

Discussion: Talk about properties of matter:

o Liquids are denser than gasses.o Molecules take up less space in liquid form than in gas form.o An absence of matter will create a vacuum.o When a vacuum exists, nature wants to create equilibrium by filling the space;

this causes pressure from the outside to push inward.

Vocabulary: Gas Pressure Vacuum

References:Experiencing Chemistry: Museum Manual Part 1. Portland, Oregon: Oregon Museum of Science and Industry, 1997. 51-54.

Matter MattersMatter MattersCandle and Rising Water


Overview:This is a demonstration to show how a vacuum is created and uses pressure to draw up a liquid.

Time: 5-10 minutes


Votive candle Clear shallow container 3 pennies 2000 mL Erlenmeyer flask Water Food coloring

Setup:Place three pennies in the bottom of the shallow container far enough apart that the flask can rest upside-down on top of them. Color the water using the food coloring. This is just to make the water more visible to the students. Fill the container with about 1 inch of water. Place the candle between the pennies and the flask over it.

Background:A candle needs oxygen in order to burn. When it burns it burns the oxygen around it and converts it to carbon dioxide and water, which are both denser than oxygen. This creates a vacuum. In order to create pressure equilibrium, the water is sucked into the flask.

Activities/procedure:This activity is done as an in-class demonstration. Light the candle and place the flask over the top. The water should be above the mouth of the glass. As the candle burns, the water will rise. Since the candle floats, it will continue to burn until the oxygen is used up.

Discussion: Explain the process by which the water is sucked into the flask. (The depth with

witch the demonstration is explained will depend on the academic level of the class. The most important concept is that the burning candle creates a vacuum which sucks up the water.)

Vocabulary: Burn Oxygen Vacuum

References: Gibson, Gary. Science for Fun: Experiments with Easy-to-Make Projects on Magnets, Sound, Light, Electricity, and Much, Much More. Brookfield, Connecticut: Aladdin Books Ltd, 1996. 108-109.

Matter MattersMatter MattersDensity Bottles


Overview:In this activity the students will explore the densities of different liquids.

Time: 15-20 minutes (this was done as a station in the liquid rotation)

Materials:For each group:

Clear 20-oz. Bottle Water Corn syrup Vegetable oil Food coloring 3 medium beakers (1 for each liquid) 3 small beakers (1 for each liquid) 6 droppers (2 for each liquid) Waste container Sponge

Teaching/demo materials: Pre-made density bottles Ocean (or other) decoration using density layers (optional) Cartesian Diver

Setup:Set the density bottles and demonstrations on the station table along with the empty bottle, the corn syrup, and the oil. Fill a flask with water and color it with food coloring. Place it on the table as well. Place three small beakers on each table, one for each liquid, and place 2 droppers in each beaker.

Background:Some liquids are denser than others. In a bottle with liquids of varying densities, the densest liquid will sink to the bottom. This is because it weighs more per volume, so it sinks. If the liquids are soluble with each other, they will eventually dissolve together, but if the liquids are not soluble in each other (such as water and oil) there will be distinct and lasting layers.

Activities/procedure:

Give the students a few minutes to explore the density bottles on the table. Ask questions about the relative densities of the liquids in the bottles. Once they have seen all the bottles, help the students make their own density bottle using corn syrup, water, and oil. Let the students decide which they think is the densest and should be poured in first. Have them do this by experimenting dropping drops of the different liquids on top of each other. The densest should be the corn syrup. Have them decide which should be poured in second and third. If they are wrong about which is the densest the layers should switch places. This can be a little difficult for the corn syrup because it is slightly soluble in water, so try to get the students to pick it to be poured in first. The density bottle should have corn syrup on the bottom, colored water in the middle, and oil on the top. If shaken, the corn syrup will eventually dissolve in the water.

Discussion: Which layer is the densest? (the bottom layer) Which layer is the least dense? (the top layer) Is the water more or less dense than the corn syrup? (less)

Continue these types of questions until the students are confident that they understand density.)

Extension: If the group grasps the concept quickly they can continue on to these topics:o Solubilityo Hydrophobic (does not dissolve in water) vs. hydrophilic (dissolves in

water)

Vocabulary: Density Hydrophilic Hydrophobic Soluble

References: Experiencing Chemistry: Museum Manual Part 1. Portland, Oregon: Oregon

Museum of Science and Industry, 1997. 1.39-1.44

Matter MattersMatter MattersDry Ice

(Identical to the Chemistry Lesson)


Overview:These demonstrations familiarize students with dry ice and its properties, and help to teach them about different states of matter. They allow students to make connections with the use of dry ice in the real world. Dry ice is a potentially dangerous substance so precautions should be taken.

Time: 45-60 minutes

Materials:For the exploration:

Cup of waterFor Screaming Metal:

Metal spoon water

For Fire Extinguisher Candle Matches Cup of water

For Balloon Magic Balloon Hot water

For Soap Experiment: Soap* Hot water Plastic container

*Note: this can be made with a homemade bubble solution (dish soap + water + glycerin or mineral oil) being substituted for the soap and hot water.For Bubbles:

Bubbles and wand Hot water Plastic container

For the class: Heavy Duty gloves Hammer (if ice doesn’t come in pellets) Tongs for handling the ice Food coloring

Demo:

Cabbage juice Graduate cylinder (large) Ammonia

Setup:This is easy to set up in table groups, with each group having the materials for all the experiments except the bubble and soap experiments. Remember to start heating hot water before the exploration time and have the soap already in the container when you go to do the demonstration.

Inform students of the dangers of dry ice! Make sure to tell them that regular H2O steam will burn badly. Even though this looks like steam, it is not. It is safe to touch CO2 gas.

Background:Humans exhale gaseous carbon dioxide (CO2), but what does carbon dioxide look like as a solid? It is dry ice. Just like water, carbon dioxide must be frozen to become a solid. It freezes at -109ºF or -80ºC, which is much colder than the 0ºC at which water freezes, so it can be very dangerous. Dry ice undergoes sublimation, a direct change from a solid to a gaseous state without becoming a liquid. Dry ice burns in the same way that boiling water will burn the skin and can cause frostbite, ice crystals form under the skin and cause tissue damage just like a burn, when touched for long periods of time. Be very careful with the ice and carefully observe the students’ exploration of the ice to ensure safety.

Exploration: The dry ice bubbles when placed in the water because it is sublimating and releasing little pockets of gas into the water, the same idea as when we blow bubbles in the swimming pool or using a straw with our drinks. The fog then rises when the ice is placed in hot water because the water molecules cool off and clump together, after mixing with the carbon dioxide. Screaming Metal: Begin by asking the students if they know why the metal makes so much noise, or if maybe the metal is trying to warn them of the dangers of dry ice. The metal screams when it comes into contact with the ice because the heat from the metal melts a bit of the ice into a gas. This gas then pushes the spoon off the ice, but the spoon quickly falls back down and the process continues causing the screech.

The water in the spoon freezes because the ice is so much colder than the temperature at which water freezes.Fire Extinguisher: The steam from the dry ice sublimating in the hot water is made up of CO2 rather than vaporous H2O. The fire burns because it is surrounded by oxygen, so when it is put in an oxygen-starved environment, the fire goes out.Balloon Magic: When dry ice gets hot, it sublimates meaning that it skips the liquid phase and goes straight to the gas phase. As the ice sits in the balloon in hot water, it sublimates even quicker, then if it was by itself and fills the balloon with CO2 gas which causes the balloon to expand. This because gas takes the shape of its container, so the same amount of gas is a lot larger than a solid of the same substance.Soap Experiment: As the hot water melts the dry ice, pockets of gaseous CO2 are released. The soap then locks in the carbon dioxide and the bubbles are full of fog.

Bubbles: As the dry ice sublimates, it causes the vapor that was explained in the exploration. The bubbles float above the carbon dioxide gas because the carbon dioxide gas is heavier than air. Demo: Put some cabbage juice in a large graduated cylinder. Put a little dry ice in the bottom. As the ice reacts with the water, it creates an acid. The juice will turn pink. Add some ammonia – it will turn green and then back to blue and purple as it forms acid. This is a fun and colorful way to explain the chemistry of the reaction between dry ice and water. It is also a good review of pH.

Activities/procedure:For exploration:

1) set ice on the table2) watch piece disappear3) put ice in cup of water4) watch ice disappear and the liquid bubble5) then put a piece of dry ice in a cup of warm/hot water6) watch the ice disappear and the fog form

For Screaming Metal:1) put some dry ice on the table2) press a spoon to the dry ice3) be very quiet4) listen to the noise that is produced5) you can also put water in the spoon 6) observe freezing of the water

For Fire Extinguisher:1) light a candle2) put dry ice in a cup of hot water3) set candle near the cup or pour the fog coming from the cup over the candle4) watch the flame die

For Balloon Magic:1) put a piece or 2 of dry ice in balloon2) add some hot water to the balloon or put balloon in the water3) tie or pinch off balloon4) watch balloon expand5) if the balloon was tied set it away from students in case it pops

For Soap Experiment:1) Put soap in plastic container2) Add hot water3) Add dry ice4) Watch the solution ooze up and even over the container sometimes

For Bubbles:1) place a cup of hot water into a large plastic container2) add dry ice to cup of hot water3) observe fog coming off of hot water and dry ice cup4) blow bubbles into container5) watch the bubbles float

Discussion: After each demonstration try to lead the students to explanations of how each

experiment works by reminding them of the special properties of dry ice.

Vocabulary: CO2- Carbon Dioxide Sublimate- during phase change the solid form skips the liquid phase and goes

straight to the gaseous phase

References: http://www.rockitscience.com/dryice1.html http://www.dryiceinfo.com/science.htm

http://www.dryiceinfo.com/science.htm

http://www.rockitscience.com/dryice1.html

Matter MattersMatter MattersEgg in a Flask


Overview:This demonstration shows how fire can be used to create a vacuum by burning up the air in a sealed container.

Time: 20 minutes


500 mL flask (opening slightly smaller than an egg) Hard boiled egg (shell removed) Matches

Setup:Prepare the eggs ahead of time. It is good to have enough for multiple demonstrations if the students want to see it again or it does not work the first time.

Background:A combustion reaction converts oxygen and carbon into solids and denser gasses. If a combustion reaction occurs in a sealed container it will burn up all the oxygen and create a partial vacuum. Nature attempts to keep gas pressure at equilibrium, so when the gas pressure outside is greater than that inside a container it creates a force pushing into the container. Vacuums create varying amounts of inward force depending on the difference between the external and internal pressure. A vacuum create by a flame in a glass, surrounding by normal external pressure, is enough to pull a soft object into the container.

Activities/procedure:Light a match. Allow it to start burning strongly (pointing it down may help) before dropping it into the flask. Immediately, set the peeled egg over the opening of the flask, insuring that it creates a good seal. Wait while the vacuum created by the match in the flask sucks the egg inside.

Remove the egg by cutting it with a table knife and taking out small pieces at a time. If the class wants to see the demonstration again make sure the flask is aired out completely before starting over.

Discussion: A vacuum is a place with no gas (or other matter) inside of it. This experiment

creates a partial vacuum.

Vocabulary: Combustion Oxygen Vacuum

References:Churchill, E. Richard, Louis V. Loeschnig, and Muriel Mandell. 365 Simple Science Experiments with Everyday Materials. New York: Sterling Publishing Co., Inc., 1997. 51.

Matter MattersMatter MattersFloating Golf Ball Demonstration


Overview:This is a demonstration to show that salt water is denser than fresh water, which allows more things to float in it.

Time: 5-10 minutes


Golf ball Concentrated salt water Tap water Food coloring Graduated cylinder just wide enough for a golf ball

Setup:Pour salt water and tap water into separate beakers. Add food coloring to the tap water so that the two can be distinguished from each other.

Background:Density is defined as the amount of mass per volume. Something that is denser than water will sink, while something that is less dense will float. A salt solution is denser than plain tap water. In a highly concentrated solution the difference is enough to allow some objects to float that would not normally float. A golf ball sinks in tap water but floats in concentrated salt water.

Activities/procedure:This activity is done as an in-class demonstration.With the water still in the beakers, show the class that the golf ball sinks in tap water but floats in salt water. Take the golf ball out of the beakers. Pour the salt water into the graduated cylinder. Add the golf ball. The golf ball will float on top. Carefully add the colored tap water by holding the graduated cylinder at an angle and pouring down the side. Once the cylinder is positioned upright, the salt water will be at the bottom, the tap water will be at the top, and the golf ball will be floating between the two layers.

Discussion: Why does an object sink or float? (It is either more or less dense than water) Which layer is the most dense? (Salt water) Which layer is the least dense? (Tap water) Is the golf ball more or less dense than the salt water? Ask as many questions of this nature for the students to begin to understand the

concept of density. (Some classes may take longer to understand than others)

Vocabulary: Density Float Mass Sink Volume

References: Experiencing Chemistry: Museum Manual Part 1. Portland, Oregon: Oregon Museum of Science and Industry, 1997. 1.67-1.70.

Matter MattersMatter MattersGel Beads


Overview:In this activity, students get to combine two liquids- one colored, one clear. When they drop the colored solution into the clear solution, it forms a bead of gel that can be examined. It is a fun and colorful way to teach students about polymers, crosslinks, and diffusion.

Time: 40 minutes

Materials:For the class:

Sodium alginate (2 wt% in water) in jars colored with food coloring Calcium chloride (1.5 wt% in water) Droppers Small strainers to remove gel beads from solution

For each student: Small plastic dish Small baggies for them to take home their beads

Setup:Place four jars of sodium alginate (one of each color) on each table with droppers for each jar. Provide a dish of calcium chloride for each student.

Matter MattersMatter MattersHot/Cold


Overview:Students will learn about how the density of liquids changes depending on the temperature. They will assist in an experiment that demonstrates this concept.

Time: 15-20 minutes (this is done as a station in the liquid rotation, along with density bottles, measuring, and sink or float)

Materials:For the station:

Hot (almost boiling) water (~1gallon or 200mL per student) Cold water Food coloring (red and blue) Ice Waste Bucket

For each group: 2-4 very small beakers or baby food jars 5 large (~1000 mL) beakers 2 large flasks

Setup:Begin boiling water long enough ahead of time that it will be hot by the time it is needed. Set the materials at the station, along with hot pads for moving the boiling water. Set out two large beakers of clear, cold water; two beakers or clear, hot water; one flask of cold water, colored blue; and one flask of hot water, colored red.

Background:As matter is heated it expands, making it less dense. Hot water is less dense than cold water, which allows it to rise above cold water. However, the temperature grade does not last long as all the water moves quickly towards temperature equilibrium.

Activities/procedure:Give each student a baby food jar and let them put two drops of their choice of food coloring in the bottom. Fill the beakers about half full with water, enough to fill about 2 cm. above the jar when placed in the water. Perform the experiment with each student in turn, allowing the others to watch. Take the student’s jar and fill it completely with hot water. Make sure the food coloring mixes with the water. Carefully drop the jar into the beaker of cold water. Looking through the side of the beaker, the students will be able to see the colored hot water rising out of the jar and going to the surface.

Discuss what happened, and try to get the students to suggest doing the experiment again but in reverse. Put cold water in the jar with the food coloring and put hot water in the beaker. The colored cold water will stay in the jar unless it is stirred slightly, in which case it will come out of the container and fall to the bottom.

If time permits, ask the students if there are other experiments related to this that they would like to try. Some of these may include, coloring both the hot and cold water different colors and watching how they mix, and others.

Discussion: Talk about how the density of water changes depending on the temperature. (as it

heats up, the molecules are further apart and therefore it is less dense.) Which is more dense, the hot water or the cold water? (cold) Which one has faster moving molecules? (hot) Which one has molecules that are farther apart, making it less dense? (hot)

Vocabulary: Density Temperature

Matter MattersMatter MattersInflating Reaction Bags


Overview:Students will make a chemical reaction in a bag with exciting results. They will learn about the ways to determine if a chemical reaction occurred.

Time: 30 minutes


Calcium chloride powder Sodium salts (Phenolsulfonphthalein) to make Phenol red indicator (this is NOT

the same as phenolphthalein indicator) Baking soda Plastic spoons Small measuring cup

For each student: Sandwich sized zip-loc bag Paper cup

Setup:Pass out a bag and a paper cup to each student. Provide a plastic spoon in each of the baking soda and the calcium chloride. To make Phenol red: use phenol red sodium salt (Phenolsulfonphthalein) and add 0.1g in 28.2mL of 0.01Molar NaOH (Sodium Hydroxide), then add ~225 mL of water.

Background:There are three ways to determine if a chemical reaction occurs:

1. Phase change2. Color change3. Temperature change

A phase change can be in the form of a gas being released in a reaction, or a precipitate forming in two liquids. A color change is often an indication of a change in pH, like in this reaction. An indicator is used to show this change. When there is a temperature change the reaction is either endothermic or exothermic. If the reaction feels cold it is endothermic (heat is absorbed), and if the reaction feels hot it is exothermic (heat is released). (see unit introduction)

Phenol red is used as a pH indicator. A solution of phenol red will have a yellow color at a pH of 6.4 or below and a red color at a pH of 8.2 and above. The sodium salt of phenol red is used widely in culture media to identify changes from neutral to acidic pH values.

Activities/procedure:Go over safety rules with the students. Calcium chloride can irritate the hands, and phenol red indicator has an acid in it, so they need to be careful to keep away from their face and not get chemicals on their hands.

Add a spoonful of baking soda and a spoonful of calcium chloride to each student’s bag. Have the class mix the two powders by carefully squeezing the outside of the bag. Come around and add some phenol red indicator (less than 5 mL) to each of the paper cups. Have the students place their cups with indicator carefully inside their bag without spilling it. Seal the bags. Once the bags have been sealed the students can mix the indicator with the powder.

Watch for these things: Temperature change—it will first turn warm (very briefly), and then cold Color change—it will go from red, to orange, to yellow depending on the pH.

The more it interacts with air, the more the pH will change. Phase change—a gas is released, causing the bag to expand.

As the bag expands, have the kids hold it away from their faces and carefully release the gas. Do NOT let the bag get so big it pops! You don’t want the chemicals to splatter.

After a few minutes of observing all of the chemical reactions that are taking place, the student can leave their bags to see how they will change over a few minutes time. Those that are tightly sealed will remain a constant color. Those exposed to air will continue to change. Most bags change color at different rates, resulting in a very colorful variance in results.

Discussion:Questions:

How do we know that a chemical reaction occurred? (you can observe all three signs of a chemical reaction - temperature change, phase change and color change)

What filled the bag when it started to expand? (The bag expanded because it filled with carbon dioxide gas, a product of the reaction

Why did the color change? (the pH changed causing the indicator to show different colors)

Did it turn a different color when you opened the bag and let air in? (The color changed because of the change in pH. The phenol red is a pH indicator, which changes color in the presence of an acid or a base. Opening the bag changes the pH, so the color changes as well. It turns from pink and red to orange and yellow).

Vocabulary: Acid Base Chemical reaction Color change Endothermic Exothermic Indicator pH Phase change Temperature change


http://www.usbio.net/Product.aspx?ProdSku=P4040 (info on Phenol red indicator)

http://www.usbio.net/Product.aspx?ProdSku=P4040

Matter MattersMatter MattersLiquid Nitrogen Demonstration


Overview:This is a demonstration lesson where students get to watch what a very cold liquid can do.

Time: 30 minutes to 1.5 hours


Liquid nitrogen Open container insulated to hold liquid nitrogen (dewar) Hammer Tongs Safety goggles Thick gloves for handling extreme temperatures

Suggested materials: Hot dogs Silly putty Tennis ball Carnations Bananas Inflated balloon Anything else that will smash when frozen in liquid nitrogen

Setup:Liquid nitrogen can be purchased from Chem. Stores. It can be kept in a closed, insolated container for a few hours, so it must be purchased the day of the activity. A full dewar (4 liters) of liquid nitrogen should be enough for this activity, and still have some left over.

In class, give the students a safety lecture on liquid nitrogen. Any contact with skin can result in frostbite. It is important that the class behave around the liquid nitrogen and stay back during the activity. Set strict rules involving this activity.

Background:Liquid nitrogen (N2) is a coolant that exists at -196 degrees Celsius, or -321 degrees Fahrenheit (-77 Kelvin). It is much colder than dry ice (CO2, which freezes at -78.5 degrees Celsius or -109.3 degrees Fahrenheit) which is capable of “burning” tissue due to its extreme cold. As a result, liquid nitrogen is even more dangerous.

Since liquids transfer heat efficiently, they make good coolants. Placing an object in liquid nitrogen will freeze it within seconds. Since most substances we use (especially food and plants) contain water, they freeze and become brittle. When items are frozen, their molecules do not move as much. This allows objects that would normally stretch, tear, or bend to shatter when sharp pressure (such as a hit from a hammer) is applied. When molecules can not move, energy is not returned as well. This is why frozen rubber balls will not bounce as well.

Another property of extreme temperature is that gases expand or contract. In heat gasses expand, but in extreme cold they contract. A balloon will shrink to about 1/10 its size when liquid nitrogen is poured over it. Moments later it will expand to its normal size as the air expands again.

Activities/procedure:This is entirely a demonstration activity. The students should not be allowed to touch the liquid nitrogen. It is important that they stay back while things are being smashed, since flying pieces could be enough to cause burns. Stress that they are not to touch the broken pieces! They can burn.

Using thick gloves pour some of the liquid nitrogen into the open container for demonstrations. The fog will make it difficult to see when the container is full, so pour until the liquid nitrogen begins to overflow. At first it may be necessary to continue to add more liquid nitrogen because it will boil off as the container cools down.

With tongs, put objects into the liquid nitrogen. Take them out and smash them with a hammer. Some things may take longer to freeze than others. Show the difference in the consistency before and after being in the liquid nitrogen. Demonstrate how most objects will return to their original state after they have heated up again (with exception of the carnations, which will wilt).

Pour some liquid nitrogen over an inflated balloon. Talk about how gas expands and contracts depending on the temperature. Watch while the balloon re-inflates as it gets warmer. It is fun to drop in a long balloon, and then watch it shrink to almost nothing, and then re-inflate as it warms up. For added fun, we used screamer balloons. After the balloon re-inflated, we let it go and the kids went nuts! Anything add some showmanship!

When a rubber ball is dropped into the liquid, it gets very hard and sounds like a pool ball when bounced. When first frozen, it may bounce pretty well since it is so solid. After a few seconds, it will almost lose its bounce. It will hit the ground and die. After a few minutes, the ball will bounce again.

At the end, a very small amount of the remaining liquid nitrogen can be poured on the floor, or down stairs or a ramp. Be VERY careful to poor away from people, as the droplets travel a long ways on clouds of vapor. It is especially interesting on a tile or linoleum floor, since it will lift the oil and dirt off and the balls of oil will slide around

until all the nitrogen has evaporated. It makes a great “spooky fog” effect that the kids love to watch. Very mad scientist!

Discussion: Discuss the difference between the Fahrenheit and Celsius (also possibly Kelvin)

temperature scales. Discuss changes in molecules with heat.

o When the object is cold, the molecules do not move as mucho Things become more brittle as they get colder.o When cold, rubber loses its bounce because the molecules can’t transfer as

much motion.o When gasses get cold, they get closer together.

Vocabulary: Celsius Fahrenheit Liquid nitrogen Molecules

References: http://www.ilpi.com/genchem/demo/liquidnitrogen/http://www.howstuffworks.com/question264.htm

http://www.howstuffworks.com/question264.htm

http://www.ilpi.com/genchem/demo/liquidnitrogen/

Matter MattersMatter MattersMeasuring


Overview:Students are given a chance to experiment with the properties of liquids. They will learn that liquids have a constant volume and change shape to fill their containers.

Time: 15-20 minutes (this was done as a station with the liquid rotation)

Materials:For the station:

Medium sized tub Water

For each student: Graduated cylinders of different sizes Beakers of different sizes Large cup Plastic bowl Any other containers of different sizes that can hold water Flat pan Quantitative Flasks

Setup:Fill the tub with water and place it on a table for the station. Place the sets of different measuring containers next to the tub. Only four or five sets should be needed if the class is rotating through stations.

Background:The Newtonian definition of a liquid is something that has definite volume but no definite shape. This means that a liquid will change shape to fills its container but its volume is constant regardless of the size of its container.

Activities/procedure:Give each student a specific volume of water, usually close to 50 mL, in his or her graduated cylinder. Allow the students to experiment with the different containers to see what their amount of water looks like in each one. The water will fill some containers completely, barely cover the bottoms of others, and overflow out of a couple of them. A given amount of water placed in a graduated cylinder may appear greater to some students than the same amount of water placed in a shorter beaker.

Discussion:Questions to ask:

What happens when you pour the water from one container to the next?Does it change shape?Does it change volume?

Have them pour their water back into the graduated cylinder to prove that it is the same volume as when they started. (Allow for some spilled water.)

Depending on the level of the group, you may cover any of the following topics:Surface tensionDisplacementFinding the volume of solids using displacement

Vocabulary: Displacement Shape Surface tension Volume

Matter MattersMatter MattersMentos Fountain Demosntration


Overview: This is a cool soda fountain that the kids really enjoy. When Mentos candy is dropped into a 2-liter bottle of soda, it produces a soda eruption. The spray tastes delicious and it is not too sticky if you use diet soda.

Time: 15 min for set up and 5 minutes for actual demonstration

Materials:For each demo:

Pushpin or large needle Thread 2 liter bottle of pop (diet cola is less sticky, but after repeated trials, we found that

room temperature non-diet cola seems to work the best… for whatever reason) Mint or strawberry Mentos (works best)—at least 7 per fountain

Setup:With the pushpin, make holes in each Mentos to thread onto a string/thread. Thread the candies onto the string, tie off, and leave a tail on at least one end. Right before the experiment, punch a hole in the lid of the soda and pour out as much soda as needed, so that when the tail is threaded through the hole of the lid and the Mentos are in the bottle with the lid on, they are not touching the soda (don’t even let it touch the soda for a second). The less soda you remove, the better. You may string the Mentos in a loop so both top and bottom strings are threaded through the hole in the lid. This makes it so you do not have to pour out as much soda.

Diagram:

Background:Mentos contain gum arabic which gives them the chewy property. Soda on the other hand, contains carbon dioxide gas (in bubbles) surrounded by water molecules which are super-attracted to each other. The clumping together of the water molecules causes surface tension, which is a measure of how hard it is to separate the water molecules. We can break the surface tension even more easily by adding the gum arabic to the soda. The Mentos then begin to dissolve leaving little pits on the surface, which are called nucleation sites-places where more carbon dioxide gas bubbles can form. This causes the contents of the soda bottle to explode, out the hold and into a fountain.

Activities/procedure:1) thread Mentos string through lid2) put in bottle and screw lid onto bottle3) drop Mentos into soda*4) run away as fast as possible

*If doing this later, tape the string to the bottle and then cut the string when you wish to start the reaction.

Discussion: Talk about surface tension

o Water (the main ingredient in soda) has a certain amount of surface tension

o If the surface tension in the soda is broken it allows the carbon dioxide to be released

o If the gas all breaks the surface tension at the same time an explosion occurs.

Vocabulary: CO2 – Carbon dioxide Nucleation site Surface tension

References: Steve Spangler Science Experiment Mentos Fountain

http://www.stevespanglerscience.com/experiment/00000109

Matter MattersMatter MattersMoving Gas


Overview:Students produce carbon dioxide by combining baking soda and vinegar. The carbon dioxide forces water from one flask to another via a tube.

Time: 15-20 minutes (this was done as a station with the gas rotation)


Baking soda Vinegar 500 mL Erlenmeyer Flask with a one hole rubber stopper 250 mL Erlenmeyer Flask with a two hole rubber stopper 400 mL Beaker Three pieces of tubing Food Coloring Spoon 100 mL graduated cylinder Water

Setup:Place one end of one of the pieces the tubing out of the top of the stopper with one hole. Place the other end of the tubing into the top of one of the holes of the two-holed stopper. Place both of the other pieces of tubing in the other hole of the two holed stopper, one out the top and one out of the bottom. Make sure there is a tight seal on all of the stoppers. Add 200 mL of water and some food coloring to the 250 mL flask. Place the two-holed stopper securely on the 250 mL flask. Add one half spoonful of baking soda to the 500 mL flask. Add 50 mL of vinegar to the 500 mL flask and quickly place the one-holed stopper securely on the flask. Place the loose end of the tubing into the 400 mL beaker.

Background:Baking soda and vinegar react to produce carbon dioxide. This is like the reaction for a volcano made in a classroom. The pressure produced by the carbon dioxide will force the colored water from the flask to the beaker. It can be hard to see gasses but we can see their effects in this reaction.

Activities/procedure:Place the two-holed stopper securely on the 250 mL flask. Add one half spoonful of baking soda to the 500 mL flask. Add 50 mL of vinegar to the 500 mL flask and quickly place the one-holed stopper securely on the flask. Watch the vinegar react with the baking soda. The carbon dioxide produced will expand and go up the tube into the 250 mL flask. As the pressure builds the carbon dioxide will force the water from the flask into the tube and then into the beaker. The reaction will continue for about 30 seconds. After all of the water has moved from the flask to the beaker, carbon dioxide will continue to move through the tubing creating bubbles.

Discussion:Thought we can’t see it, carbon dioxide filled the flask and forced the water to move to the beaker. The flask is now filled with carbon dioxide. (Assuming there is a residue of baking soda in the bottom). What would happen if we added more baking soda to the flask? Would there be more of the reaction? (Add more baking soda, it shouldn’t react.) We have too much baking soda and not enough vinegar. What would happen if we added more vinegar? (Add more vinegar and quickly replace the stopper.) No matter how much baking soda we would have added, there wasn’t enough vinegar to make the reaction happen. The vinegar was called a limiting reagent. The vinegar limited the amount of reaction. What would happen if we swirled the flask with the reaction? (The reaction would go faster.) Swirling the flask is a catalyst to the reaction. A catalyst is something that helps the reaction go faster.

Vocabulary: Carbon Dioxide Catalyst Limiting Reagent Pressure


Matter MattersMatter Matters“Oobleck”


Overview:Students get a chance to learn about non-Newtonian fluids with a hands-on demonstration.

Time: 15-30 minutes


Cornstarch Water Plastic bowls or containers Large container

For each student pair: Plastic tub

Setup:Pour some cornstarch into large container (about enough to cover the bottom a few cm deep). Add small amounts of water at a time and mix until it reaches the point where it is liquid when left standing but solid when pressure is applied. This should be done slowly as the solution gets too runny when prepared quickly, and the students can’t pick it up.

Background:A non-Newtonian fluid is something that does not fit any one of Newton’s definitions of a solid, a liquid, or a gas. The definitions Newton gave are:

Solid—has definite shape and definite volumeLiquid—has definite volume but indefinite shapeGas—has indefinite shape and indefinite volume

When mixed in the proper ratios, cornstarch and water make a non-Newtonian fluid. It does not fit any specific definition of solid, liquid, and gas, but fits into two different categories. This fluid can be classified as either a liquid or a solid, depending on the amount of pressure that is applied. When left standing, this mixture is a liquid, but once there is pressure it becomes a solid. At standard pressure, this liquid is so close to being a solid that the slightest increase in pressure is enough to change it. It can be difficult to grab a handful of it out of a basin, because it feels solid at first.

Another factor accountable for the state change is static electricity. When the mixture is stirred or moved it creates enough static electricity that, when paired with the change in pressure, is enough to change states.

A comparison can be drawn to standing in sand where it meets the water. When you run on it (apply pressure), it feels solid. When you let your feet stand in one place as the waves come in, the sand particles are allowed to move over the top of each other, and it becomes fluidized, allowing your feel to sink. This is essentially what is happening when the Oobleck goes from a solid feeling substance to an oozing liquid. Less pressure allows to molecules to move over each other.

Activities/procedure:Give each student, or small group of students, a container of cornstarch mixture, and go over some rules of how to play with it without loosing it on the ground or getting it on their neighbor. It will make a HUGE mess, but cornstarch is non-toxic and washes away quickly.

Explain why it is an example of a non-Newtonian fluid. Allow them to experiment with it on their own. Once it is dry, it will brush off their hands like a powder. Ensure them that it will come off, as many kids (especially really young ones) are very concerned that this goopy stuff will never come off! Take them to wash hands immediately afterwards, in a tub of water or hose outside. Do not wash it down the sink! It will clog it!

Discussion: Why is this mixture an example of a non-Newtonian fluid? (It has properties of

both a solid and a liquid.) What states of matter does it fit with? (It can sit in one place and keep its shape, to

a degree, much like a solid. However, it can run and take the shape of a container like a liquid.)

What do you do to make it change states? (When pressure is applied, the substance doesn’t move. When allowed to relax, the molecules in the substance can run over the top of each other like a liquid.)

Vocabulary: Cornstarch Liquid Non-Newtonian fluid Solid

References: http://www.madsci.org/posts/archives/mar98/889944863.Ch.r.htmlhttp://antoine.frostburg.edu/chem/senese/101/liquids/faq/starch-thicken.shtml

http://antoine.frostburg.edu/chem/senese/101/liquids/faq/starch-thicken.shtml

http://www.madsci.org/posts/archives/mar98/889944863.Ch.r.html

Matter Matters Matter MattersSilly Putty


Time: 40 minutes


Wood glue Borax Water Food coloring Syringes

For each student: Styrofoam cup Wood stir sticks

Setup:Weigh out 15 grams of wood glue into each cup and add one or two wooden stir sticks. Make a 2wt% Borax solution in labeled cups and place it at a station. Set up two other stations, one with containers of water, and one with food coloring. Put syringes at the Borax and water stations. Make sure the syringes have clear marking at 8 milliliters for the Borax and 5 milliliters for the water.

Background:Homemade silly putty is a crosslinked polymer gel. The active ingredients are the polyvinyl alcohol in wood glue and the sodium borate in Borax. Sodium borate forms crosslinks between the polyvinyl alcohol polymers. Rather than acting as a solid, like Jell-O, this gel acts as a viscous liquid. The viscosity of the substance is determined by the length of the polymer chains.

Store bought silly putty is much different that homemade silly putty. It is not a gel, so it does not have any crosslinks. Its viscosity is a result of the length of the chains of polydimethylsiloxane (PDMS). The long polymers get tangled in each other, resulting in the stretchy, bouncy substance known as silly putty.

Activities/procedure:Give each student a cup with stir sticks and 15 grams of wood glue. Send them to the water station. Have each one add 5 mL of water to his or her cup. Move to the food coloring station. Tell them to add no more than three drops of food coloring to each cup. Combinations of colors can be added to create different colors. (For purple use 1 drop of blue and two drops of red, and for orange use 1 drop of red and two drops of

yellow. Different combinations can create different shades.) Once the food coloring is added, the students should stir their ingredients until they are well blended. Last, add 8 mL of Borax solution. The crosslinks will begin forming immediately upon contact between the wood glue and the Borax. Stir the silly putty as well as possible with the sticks. Once the silly putty becomes too viscous for the sticks, take it out and knead it until it has a rubbery consistency. If the silly putty is too gluey, wet hands slightly and knead in the water.

A fun activity to do after making silly putty is to have a bounce contest with prizes.

Discussion: Talk about the chemical crosslinks in silly putty formed between the sodium

borate in the Borax and the polyvinyl alcohol in the glue. Which chemical is the polymer and which is the crosslink? (The glue forms the

polymer, the Borax provides the crosslink) Is the silly putty a liquid or a solid? (It has properties of both, making it a non-

Newtonian fluid) What is the difference between this silly putty and the kind from the store? (This

putty is a different material. It doesn’t bounce as well, and it doesn’t lift comics off the page.)

Vocabulary: Borax Chemical crosslink Gel Non-Newtonian fluid Polymer Polyvinyl alcohol Sodium borate Viscosity

Matter MattersMatter MattersSink or Float


Overview: Students learn the meaning of density by trying to explain why some objects float in water while others sinks.

Time: 15-20 minutes (this can be done as a station in the liquid rotation, it also works well to do it as a group)


Objects of different density such as:Golf ballMilk cartonCans of cola (regular and diet)Empty soda canLidsBlock of woodLeafPencilMarker, etc

Tub of water Sink or Float activity sheet

Setup:Do this activity as a station during station time so that the students all get to be a part of the activity and are not jostling around for space

Background:Density is mass divided by volume. When you have two objects of the same mass, but with different volumes/ sizes, the object with the smaller volume will be denser because the mass is not as widely spread throughout the container, whereas a huge object of the same mass is less dense because each cubic foot has less mass than that of the smaller object. Objects of different density behave differently when placed in a tub of water. Less dense objects float on the water while more dense objects sink to different depths of the tub. The more dense the object the closer it will sink to the bottom of the tub.

Activities/procedure:1) Set the tub of water in front of the students along with the objects you have

gathered, or you can let the students gather their own objects to test.

2) One at a time let students drop objects into the water to see how well they sink or float.

3) Have the students draw a picture of the tub with their objects in the water, and label the denser and less dense objects, or else show a partner which objects were the densest.

Extension: If this is an easy concept for the group to understand, you can continue on to the variable of surface area. Show that if you put a piece of paper or card stock in flat it will float, but if you put the same piece in vertically it will sink. The surface tension of water is able to hold up something with a large surface area even if it is denser than water, but when only a small surface area is placed in the water, the object will sink.

Discussion: Why do some things float and others sink? (It is either more or less dense

than water) What does this say about their densities relative to the density of water?

(Objects that sink are denser than water, while objects that float are less dense than water)

Vocabulary: Density Float Mass Sink Volume

References:Experiencing Chemistry: Museum Manual Part 1. Portland, Oregon: Oregon Museum of Science and Industry, 1997. 1.87-1.90.

Matter MattersMatter MattersSodium Acetate Towers


Overview:This activity demonstrates an exothermic phase-changing reaction. It happens quickly so the students can see the phase change right in front of them.

Time: 20-30 minutes


Sodium acetate 150 mL flask Glass stopper De-ionized water Plastic tray

Setup:Preparing the super saturated solution takes about 1 ½ hours, so start well in advance. Prepare more than one at once in case one of them does not work.

Weigh out 50 g. of sodium acetate into the flask. Rinse the inside and outside of the flask carefully with DI water to insure that none of the salt is left on the surface. Add water to about the 75 mL mark. Boil the flask(s) moderately on a hot plate, rinsing as necessary. Boil the solution down to 50 mL. This will take around half an hour. Remove the flask from the heat, insert the stopper (making sure it is sealed), and let the solution cool for about an hour.

Background:A solution is any solid dissolved in a liquid (usually water). A solution is saturated when the liquid can no longer hold any more of the solid. If you add sugar to tea until there is sugar sitting at the bottom that will not dissolve, the tea is saturated with sugar. You can dissolve much more sugar in hot tea than in iced tea. The increased temperature creates more space for the sugar molecules to dissolve into. A super saturated solution is created when the liquid is heated to dissolve more of the solid. The solid will remain in solution when the liquid is cooled as long as it does not come in contact with any of the solid out of solution.

Activities/procedure:Sprinkle a small amount of sodium acetate salt onto a tray. Slowly pour the super saturated solution onto the salt, being careful not to let it drip down the side of the flask. A solid should form instantly upon contact with the salt. By poring carefully you should be able to create a tower of sodium acetate.

Allow the students to feel the sodium acetate tower. The reaction is exothermic so it will feel hot. Be carefully that the students do not put their fingers inside the mound, as the sodium acetate inside may be hot enough to cause mild burns.

Wash hands immediately after touching the sodium acetate. Tell the students not to touch their faces or other students before washing their hands.

The sodium acetate can be reused for this experiment. To dispose of, dilute with water before pouring down the drain.

Discussion:Optional:Do a demonstration using salt and a bottle of water. Show how salt dissolves in water. Add enough salt to saturate the solution. Prove that it is saturated by shaking the bottle of water and showing that there is still salt left in the bottom of the container.Ask:

Would the salt dissolve if I added more of it to the solution?How could I make it dissolve?

Water can dissolve more salt if it is heated. This is called a super saturated solution.

Questions:How do we know this is a chemical reaction?What did it feel like?

A chemical reaction has to have either a phase change, a color change, or a temperature change. This reaction had a phase change, going from liquid to solid, and a temperature change because it became very hot. It is an exothermic reaction, meaning that it releases heat and feels hot.

Vocabulary: Dissolve Exothermic Phase change Reaction Saturate Sodium acetate Super saturated solution


Matter MattersMatter MattersSolid, Liquid, Gas Game


Overview:This is a game that the students can play to learn how molecules move in different states.

Time: 10 minutes

Materials:None

Setup:None

Background:Molecules move differently in different states of matter. In a solid the molecules are close together and move very little. As the molecules heat up and become a liquid they start to spread out and move more. Once they heat up enough to become a gas they are far apart and moving very quickly. For this reason, when matter is heated it expands.

Activities/procedure:Take the students to an open area either in the classroom or outside (if the weather permits). Briefly explain the concept of how molecules spread out and move faster as they get warmer. Tell them that each one of them is a water molecule and it is very cold so they are frozen into ice. The students should come in close together and hold very still. Give a simple scenario that would cause the ice to melt. When you say “liquid”, the students should begin to move slowly and spread away from each other. Explain another scenario that would cause the water to evaporate. Upon hearing the word “gas”, the students should break completely away from each other and run (carefully) around the entire area. Continue this activity with different scenarios changing between different states of matter.

Discussion:Talk about what happened at each different state of matter. Ask the students to describe the differences between the states. Point out that as they got warmer and changed states they took up more space. That is my matter expands as it is heated.

Vocabulary: Condense Evaporate Freeze Gas Liquid Melt Solid

Matter MattersMatter MattersSolid Stations


Overview:This is an introduction to solids. It allows the students to explore different solids on their own and observe the different properties.

Time: 30 minutes

Materials:For each table:

Cotton swab Coffee filter Marble Marshmallow Empty balloon Any other small solids with different properties

Random objects that may not seem “solid” i.e.: Sand Gravel Sugar cubes Salt Pipe cleaner Rubber bands

Bottles with liquid in them Silly putty (non-Newtonian Fluid) Cotton balls Bubbles (example of all three) String Spaghetti (ask them about cooked)

Setup:Set some of each item at each station

Background:The Newtonian definition of a solid is that it has definite shape and definite volume. Many things fit this definition but have very different properties. Some solids will change shape when pressure is applied, but they are still solid because they maintain their shape even when placed in a different container.

Activities/procedure:Give students a chance to explore. Allow them to play with the different objects and determine what they all have in common. Have the students make observations about differences in the solids. Let them attempt to build things with some of the solids from the bags. This is mostly free exploration time for the students. Ask questions like ‘is it still solid if it is in many pieces?’ ‘What if it is soft or squishy?’


What did all the objects have in common?Can you come up with a definition for a solid from what you observed?

Newton defined a solid as something with definite shape and definite volume.What were some differences you observed?Were some solids better for building than others?

Solids have different properties that make objects better for certain tasks. It is hard to build a tower with a piece of string, but bricks would not work for tying something together.

Vocabulary: Matter Newtonian Properties Shape Solid Volume

Matter MattersMatter MattersStraws and Water


Overview:Students use simple materials and activities to learn about density of gasses and gas pressure.

Time: 15-20 minutes (this was done as a station in the gas rotation)


Medium sized plastic tub Water Tub of bubble solution

For each student: Plastic drinking straw

Setup:Fill the tub about halfway with water. Set it on the table to be used for the station along with a box of clean drinking straws. Fill another tub with bubble solution mixed with water.

Background:Gasses are much less dense than liquids. It is the property that causes them to rise in liquids, such as carbonation in soda pop or bubbles blown through straws. Although gasses can change volume, they tend to stay at a standard pressure whenever possible, giving them the ability to move or hold in place other forms of matter in order to maintain equilibrium.

Activities/procedure:Give each student a drinking straw and allow the group to experiment with gasses by blowing bubbles in the water. After a few minutes, demonstrate a different experiment for them to try. Draw up water in the straw by creating a seal over one end with your finger and pulling the straw out of the water. The water will stay in the straw even though the bottom of the straw is open.


Where did the bubbles go after you blew them (did they rise or fall)?What does this say about the density of gas?

Talk about how gasses are less dense than liquids, causing them to rise to the surface.Questions about the suction experiment:

Why did the water stay in the straw?What was holding it in?

The gas pressure was holding it in. Since there wasn’t very much gas in the straw it would have had to create a vacuum in order to let the water come out. The force of the pressure inside the straw was larger than the force of gravity, so the water stayed in the straw.

Vocabulary: Density Gas Pressure Suction

Matter MattersMatter MattersSynthetic Snot


Overview:Students get to create and play with a non-Newtonian fluid.

Time: 15 minutes to make, 1 hour to set, 15 minutes to explore

Materials:For each station:

Water (40mL) Gelatin (7g) Corn syrup (65mL) Graduated cylinder (50mL) Large beakers or similar containers (1 for 4 students) Spoons

Setup:Boil water before beginning the activity to save time.

Background:The mixture of corn syrup and gelatin is another example of a non-Newtonian fluid. It creates a substance often called “synthetic snot” due to its close resemblance to the real thing. It cannot be classified as either a solid or a liquid because it will hold a shape but also form to the shape of a container. This is a result of the nature of the gelatin, a polymer. Due to the size of the molecules it is difficult for it to be classified as a specific state of matter.

Activities/procedure:Measure 40 mL of boiling water with a graduated cylinder into each beaker. (Make enough beakers of “snot” so that the students are in groups of around four.) Pour in 7g of gelatin and mix thoroughly. Let the gelatin solution sit for a few minutes. Measure out 55 mL of corn syrup and add it to the mixture. Stir vigorously until it has a sticky, rubbery consistency.

Allow the students to play and experiment with the fluid. The mixture will not harm the hard surfaces (such as tables) that it touches, but it is difficult to remove. Talk about how this is a non-Newtonian fluid.


Why is synthetic snot classified as a non-Newtonian fluid?What two states is it between?What does synthetic mean?

Synthetic means that it is made in a laboratory with chemicals, rather than occurring naturally.

Vocabulary: Non-Newtonian fluid Polymer Synthetic

References:Experiencing Chemistry: Museum Manual Part 1. Portland, Oregon: Oregon Museum of Science and Industry, 1997. 43.121-43.123

Take Home Recipe1.5 tsp gelatin (7.5g).25 cup corn syrup (60mL)3tbs hot water (45mL)

Matter MattersMatter MattersSyringes and Gas Pressure


Overview:Students will experiment with gas pressure and suction using syringes attached with rubber tubing.

Time: 15-20 minutes (this was done as a station in the gas rotation along with moving gas, balloon vacuum, and straws and water)


Rubber tubingFor each student:

Large syringe

Setup:Attach the syringes in sets of two using the tubing. Stick the tubing over the small end (where a needle would go) of each syringe and insure that there is a tight seal.

Background:Although gasses cannot usually be seen, they are a form of matter and can exert force on other objects. When gas is compressed it exerts outward force in attempt to maintain equilibrium. Likewise, if a gas is spread out to fill a large container the gas outside, at very high pressure relative to the inside of the container, will exert inward force. The condition when the pressure inside a container is much lower than the outside, due to a lack of gas to fill the space, is known as a vacuum. If a vacuum exists it will attempt to reach equilibrium by pulling the sides of the container closer together to create a smaller volume; this force is called suction.

Activities/procedure:Divide the students into pairs and give each pair two syringes connected by tubing. Allow the students to have small competitions by seeing who can push the syringe in the farthest while his or her partner pushes in on the other side (similar to tug-o-war). Do the reverse and see who can pull the syringe out the farthest. In both cases the gas pressure is exerting force to make the activity difficult, the first one because the gas is being compressed, and the second one because a partial vacuum is formed.

After a few minutes of experimentation, change the activity. Remove the stopper from one of the syringes and place the open end on an area of skin. Make sure there is a good

seal. Slowly pull on the stopper of the attached syringe and watch as the skin is sucked up. This is an example of suction.

Another activity that can be done at this station is having competitions of who can shoot the stopper out of a syringe the farthest. This is done by allowing as much air into the system as possible and inserting the stoppers pulled out all the way. Push down quickly on one of the stoppers and aim the other end out to get as much distance as possible. Be careful that the students do not point the syringes and each other.


What is in the syringes?Why is it difficult to push both ends in at the same time?Why is it difficult to pull both ends out?What caused skin to be sucked up?How did the stopper shoot out of the syringe?

The gas inside the syringes wants to maintain a certain pressure. Pushing or pulling on the stoppers changes the pressure, so the gas puts out force to try to keep the pressure the same. The gas will try to change the size of its container to keep pressure the same. That is why skin gets sucked in when someone pulls out on the other stopper and why the stopper flies out if someone pushes in on the other end.

Vocabulary: Gas Pressure Suction Vacuum

Matter MattersMatter MattersWorksheet Index

Worksheet:

Sink or Float

Page:

47

SKIESMatter Matters

Sink or FloatPredictions:

Experiments:

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