What is Science?

Science & Measurement

A. The Nature of Science

* 1. Science is the total collection of knowledge gained by man’s observation of the physical universe.

2. Science tries to answer the questions how and what (not why).

B. Two main types of science

1. Pure science – attempts to gain new knowledge; discoveries; research.

2. Applied science (technology) is the use of science in practical ways.

C. Physical Science

1. Chemistry – study of matter and the changes it undergoes.

2. Physics – study of energy & motion.

D. Limitations of Science

1. Cannot make value judgments.

2. Cannot prove a universal negative.

3. It is as limited as our instruments.

E. Scientific Statements

1. Facts – observable and indisputable.

2. Data – information gained from experimentation.

3. Laws – statements that describe patterns in nature with no known exceptions.

4. Theories – explanations based on evidence (may be wrong).

5. Models – man-made ideas to help us visualize scientific concepts.

Scientific Method

• The scientific method is an organized plan for gathering, organizing, and communicating information.

• The goal of any scientific method is to solve a problem or to better understand an observed event.

F. The Scientific Method

1. Identify the problem (in the form of a question).

2. Gather information by research.

3. Form a hypothesis (an educated guess).

4. Experimentation.

5. Analyze data & make conclusions.

6. Make predictions.

Observation

• 1. Observation – is information you obtain with your senses.

• What do you see?

• What do you hear?

• What do you smell?

• What do you feel?

• What do you taste?

observation

What you see

• The most direct way to gain knowledge about something in nature is to observe it.

• Your ability to observe can be extended by using tools such as microscopes, telescopes, thermometers, and rulers.

What you smell

• Many times scientists can identify the presence of a chemical, bacteria, or plant by its scent.

Can you identify the smell in the containers?

Good Smells

Touch and Feel

Texture –rough or smooth

Taste• Determining concentration through taste

What do you hear?

• Scientist record sounds of animals to determine how species communicate with each other.

• Sounds

Making a Question

• After evaluating your observations, ask a question. What do you want to find out? State the problem as a question. Make the question as specific as possible.

• Step_One__Ask_a_Question

Hypothesis

• A hypothesis is a proposed answer to the question you formulated.

• A hypothesis is an educated guess at the possible answer to the question.

• What do you think is the cause of the problem you are studying? State a logical answer to your question. This answer, which is your hypothesis, should give one possible explanation for the cause.Step_Two__Form_a_Hypothesis

Hypothesize

Planned Experiment

• Scientist perform experiments to test their hypothesis.• An experiment must be accurate and précised in order

to be reproducible. • Accuracy – the closeness of a measurement to the true

value of what is measured.• Precision – is a gauge of how exact a measurement is.

In other words, to you get the same results each time or are the measurement values very close each time you measure.

Plan Your Experiment

• The goal of an experiment is to test your hypothesis. What is the variable? What will be the control? Write a clear step-by-step procedure so that another person can repeat the same process

Components of an Experiment

• Variable – in an experiment any factor that can change is called a variable.

• Manipulated Variable – the variable that causes a change in another.

• Responding Variable – the variable that changes in response to the manipulated variable.

• Control Experiment – has two test groups- the control group and the experimental group. The control group is the standard by which any change can be measured.

Vocabulary

• Constant – The factors that are kept the same.

• Variable – The factor that is changed by the person doing the experiment

• Investigative tools

Researching an Experiment

• List the materials necessary to conduct the experiment

• Design the steps and procedures for the experiment.

• Design how data will be collected.

Analyze Data

• Evaluate – Do you see any trends or patterns in the data? Do the data support your hypothesis or prediction? Do you need more information?

Step_Four__Analyze_the_Results_of_the_Experiment

Drawing a Conclusion

• State your conclusion based on your data. Your data should either support your conclusion or lead you to another hypothesis. Have any new questions or problems come up?

• .

Step_Five__Draw_a_Conclusion

Chart

Lab SafetyLab Safety

General Safety RulesGeneral Safety Rules

1. Listen to or read instructions carefully before attempting to do anything.

2. Wear safety goggles to protect your eyes from chemicals, heated materials, or things that might be able to shatter.

3. Notify your teacher if any spills or accidents occur.

General Safety RulesGeneral Safety Rules

4. After handling chemicals, always wash your hands with soap

and water.5. During lab work, keep your

hands away from your face.6. Tie back long hair.

General Safety RulesGeneral Safety Rules

7. Roll up loose sleeves.8. Know the location of the fire

extinguisher, fire blanket, eyewash station, and first aid kit.

9. Keep your work area uncluttered. Take to the lab station only what is necessary.

General Safety RulesGeneral Safety Rules

10. It is suggested that you wear glasses rather than contact lenses.

11. Never put anything into your mouth during a lab experiment.

12. Clean up your lab area at the conclusion of the laboratory period.

13. Never “horse around” or play practical jokes in the laboratory.

Chemical SafetyChemical Safety1. Wear protective goggles and a

lab apron whenever heating or pouring hazardous chemicals.

2. Never mix chemicals together unless you are told to do so (and then only in the manner specified).

3. Never taste any chemicals (you should never taste anything in the lab).

Chemical SafetyChemical Safety

4. Follow the instructions of your teacher when disposing of all chemicals.

5. Wash your hands after handling hazardous chemicals.

Electrical SafetyElectrical Safety1. Lay electrical cords where

no one can trip on them or get caught in them.

2. Be sure your hands and your lab area are dry before using electrical equipment.

3. Never poke anything into electrical outlets.

First AidFirst Aid

Injury: BurnsWhat To Do: Immediately flush

with cold water until burning sensation is lessened.

First AidFirst Aid

Injury: Cuts, bruisesWhat To Do: Do not touch an open wound

without safety gloves. Pressing directly on

minor cuts will stop bleeding in a few minutes. Apply cold compress to bruises to

reduce swelling.

First AidFirst Aid

Injury: EyesWhat To Do: Flush eyes

immediately with plenty of water For several minutes. If a foreign object is lodged in the eye, do

not allow the eye to be rubbed.

H. SI - International System of Units1. Based on multiples of 102. Common metric prefixes:

a. mega- (M) 1 000 000 x b. kilo- (k) 1 000 x c. hecto- (h) 100 x d. deka- (da) 10 x e. deci- (d) 0.1 x (1/10) f. centi- (c) 0.01 x (1/100) g. milli- (m) 0.001 x (1/1000) h. micro- (u) 0.000 000 001 x

1 Length The distance from one point to another point.

• Measured in meters (usually in centimeters)

• Measured with a ruler, meter stick, or measuring tape.

2 Volume The amount of space a substance occupies.

• Measured in liters (usually milliliters)

• Measured with a Graduated Cylinder

• Need to measure in the middle – at the meniscus

The right way to use a cylinder

The wrong way to use a cylinder…

Measuring Volume

We will be using graduated cylinders to find the volume of liquids and other objects.

Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water.

What is the volume of water in the cylinder? _____mL

What causes the meniscus?

A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.

Measuring Liquid Volume

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Pay attention to the scales for each cylinder.

Measuring Solid Volume

10 cm

9 cm

8 cm

We can measure the volume of regular object using the formula length x width x height.

_____ X _____ X _____ = _____

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We can measure the volume of irregular object using water displacement.

Amount of H2O with object = ______

About of H2O without object = ______

Difference = Volume = ______

3 MassThe amount of matter in a substance

• Measured in grams

• Measured with a triple beam balance

• When balanced, add all numbers together

Measuring Mass

We will be using triple-beam balances to find the mass of various objects.

The objects are placed on the scale and then you move the weights on the beams until you get the lines on the right-side of the scale to match up.

Once you have balanced the scale, you add up the amounts on each beam to find the total mass.

What would be the mass of the object measured in the picture?

_______ + ______ + _______ = ________ g

Measuring Mass – Triple-Beam Balance

Click here to try an online activity.

1st – Place the film canister on the scale.

2nd – Slide the large weight to the right until the arm drops below the line. Move the rider back one groove. Make sure it “locks” into place.

3rd – Repeat this process with the top weight. When the arm moves below the line, back it up one groove.

4th – Slide the small weight on the front beam until the lines match up.

5th – Add the amounts on each beam to find the total mass to the nearest tenth of a gram.

4 Time How long an event takes to occur.

• Unit is the second (s).

• Tool is the clock (stopwatch).

5 Temperature The amount of kinetic energy a substance has.

• Measured in degrees Celsius• Measured with a thermometer

6. Density

a. How compacted the matter is in a substance.

b. D = m / v

c. Objects float if their density is less than the density of the fluid they are in.

Density

Density compares the mass of an object to its volume

D = mass = g or g

volume mL cm3

Note: 1 mL = 1 cm3

Osmium is a very dense metal. What is its

density in g/cm3 if 50.00 g of the metal occupies

a volume of 2.22cm3?

1) 2.25 g/cm3

2) 22.5 g/cm3

3) 111 g/cm3

Solution

2) Placing the mass and volume of the osmium metal into the density setup, we obtain

D = mass = 50.00 g = volume 2.22 cm3

= 22.522522 g/cm3 = 22.5 g/cm3

lecturePLUS Timberlake 65

Volume Displacement

A solid displaces a matching volume of water when the solid is placed in water.

33 mL

25 mL

lecturePLUS Timberlake 66

Learning Check

What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?

1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3

33 mL

25 mL

67

Solution

2) 6 g/cm3

Volume (mL) of water displaced = 33 mL - 25 mL = 8 mL

Volume of metal (cm3) = 8 mL x 1 cm3 = 8 cm3

1 mLDensity of metal =

mass = 48 g = 6 g/cm3

volume 8 cm3

Metric Units

The basic unit of length in the metric system in the meter and is represented by a lowercase m.

Standard: The distance traveled by light in absolute vacuum in 1⁄299,792,458 of a second.

Metric Units

1 Kilometer (km) = 1000 meters

1 Meter = 100 Centimeters (cm)

1 Meter = 1000 Millimeters (mm)

Which is larger?

A. 1 meter or 105 centimeters

B. 4 kilometers or 4400 meters

C. 12 centimeters or 102 millimeters

D. 1200 millimeters or 1 meter

Click the image to watch a short video

about the meter.

Metric Units

Mass refers to the amount of matter in an object.

The base unit of mass in the metric system in the kilogram and is represented by kg.

Standard: 1 kilogram is equal to the mass of the International Prototype Kilogram (IPK), a platinum-iridium cylinder kept by the BIPM at Sèvres, France.

Metric Units

1 Kilogram (km) = 1000 Grams (g)

1 Gram (g) = 1000 Milligrams (mg)

Which is larger?

A. 1 kilogram or 1500 grams

B. 1200 milligrams or 1 gram

C. 12 milligrams or 12 kilograms

D. 4 kilograms or 4500 grams

Click the image to watch a short video

about mass.

Kilogram Prototype

Metric Units

Volume is the amount of space an object takes up.

The base unit of volume in the metric system in the liter and is represented by L or l.

Standard: 1 liter is equal to one cubic decimeter Metric Units

1 liter (L) = 1000 milliliters (mL)

1 milliliter (mL) = 1 cm3 (or cc) = 1 gram*

Which is larger?

A. 1 liter or 1500 milliliters

B. 200 milliliters or 1.2 liters

C. 12 cm3 or 1.2 milliliters*

Click the image to watch a short video

about volume.