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Gen. Chem Solutions 2011

Name: _____________________________________ Per: _______________________

Unit 9 Homework and Lab Packet

Solution ChemistryWord Sort Concept

CirclesReading

Guide 15.1 and 15.2

Wordle Types of Solution

demo notes

Solubility curves I

Solubility curves II

Concentrations

Making Solutions Lab

Practice

Dilution Delusion

Dilution Delusion Lab

Layout

Analysis of Kool-Aid Jammers

Alka-Seltzer and Gas Solubility

That Was a Killer Cup of Coffee

Identification of Unknown Substances

Unit 8 Homework Grade: ________________________________

Overall Objective: Understand and apply the properties of water and how they relate to solutions.

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Iowa Model Core standards addressed:o Understand and applies knowledge of the structure of atomso Understands and applies knowledge of the structure and properties of mattero Designs and conducts scientific investigationso Uses technology and mathematics to improve investigations and communications

Key Concepts:1. Understand and describe the basic properties of water and ice and how they effect

the world around you.2. Explain the high surface tension and low vapor pressure of water in terms of the

structure of the water molecule and hydrogen bonding (15.1.1)3. Distinguish between solvent and solute (15.2.1)4. Describe what happens in the solution process (15.2.2)5. Explain why all ionic compounds are electrolytes (15.2.3)6. Distinguish between suspension and solution (15.3.2)7. Identify the distinguishing characteristic of a colloid (15.3.2)8. Identify the factors that determine the rate at which a solute dissolves (16.1.1)9. Identify the units usually used to express the solubility of a solute (16.1.2)10.Identify the factors that determine the mass of solute that will dissolve in a given

mass of solute (16.1.3)11.Solve problems involving the Molarity of a solution (16.2.1)12.Describe the effect of dilution on the total moles of solute in solution (16.2.2)13.Define percent by volume and percent by mass solutions (16.2.3)

Concept Circles

For the first two circles, decide which term does not belong and lightly shade in that segment of the circle. Be prepared to support your decision.

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Discuss which term in each circle you shaded in and explain your decision to do so.

Now, for the two concept circles below, instead of shading in the term that does not belong, read the three terms provided and decide on one term with similarities to the other three and write it in the blank segment. Be prepared to support your decision.

Reading Guide 15.1 and 15.2 Part 1

Create two more concept circles to be shared in class.

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Colloid emulsion

Foam ?

Hieroglyphics

Symbols Pictures

Consonants

Punt Nile

Michigan Red

Stirring increase heat

Ways to ? speed up dissolving


One concept circle must be created using Section 15.1 in your text. The second one will use Section 15.2.

Tips:1) Create a short list of 5 or 6 terms or concepts from section 15.1.2) Be sure there is something in common between the terms. 3) Place three of the terms in one circle, leaving one spot blank.4) Repeat for section 15.2

15.1

15.2

Word Sort

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In your group, work together to arrange the following terms into two or more lists. Each list must have meaning. You may arrange them any way you wish but each list must have at least two words in it.

SolventSuspensionColloidUnsaturated solutionMiscibleMayonnaiseBloodJell-oWater and ethanolSaltmarshmallow

SoluteSaturated solutionImmiscibleConcentrationKool-aidEspressoTeaOil and waterSugarWaterpaint

Write your lists with a title here

WordleFrom www.wordle.net“Wordle is a toy for generating “word clouds” from text that you provide. The clouds give greater prominence to words that appear more frequently in the source text. You can tweak your clouds with

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http://www.wordle.net/


different fonts, layouts, and color schemes. The images you create with Wordle are yours to use however you like. You can print them out, or save them to the Wordle gallery to share with your friends.”

o You will create a “Wordle” using key terms from Section 16.1 in your text book (p.470-476). What terms you use are your decision but they must meet the theme of your Wordle- “Properties of Solutions.”

o Don’t limit yourself to bold-print. Look at the figures and pictures for main ideas. This will make your Wordle more meaningful if you use prior knowledge to help you.

o The thing is, wordle.net does not completely work here at school due to the inappropriate content on some posted content on the site and since the site is not censored you must complete this at home. If you do not have internet access at home you will complete a Wordle on a blank sheet of construction paper using colorful lettering. I have construction paper if you need some.

o Use the Frequently Asked Questions page if you need any help.

o You will present your wordle to your team and choose a team representative to present to the class.

Type of Solutions Demo

Part

Substance What happened when we added one small crystal?

Unsaturated, Saturated,

Supersatured?

1 5ml water with 15g of sodium acetate

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2 After heating

3 After cooling

4 After crystal explosion

1. Yes or No: Can you determine if a clear solution is unsaturated, saturated, or supersaturated by looking at it?

________________________________________________________________________

2. If a solution has an unknown concentration, how would you determine if it was unsaturated, saturated, or supersaturated?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

3. List the steps needed to make a saturated solution.

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Solubility Curves I

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1. If you put 75g of sodium nitrate in 100g of water at 60oC, what type of solution would you have?

2. At what temperature does 142g of KI become a saturated solution? (assume 100g of water)

3. What type of solution occurs at 70oC when 51g of KCl is dissolved to 100g of water?

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4. Which substance(s) on the solubility curve do you think are gases? Why?

5. How much sodium nitrate can you dissolve in 100g of water at 78oC?

6. If you wanted to dissolve 44g of potassium chlorate, would you need to raise or lower the temperature of the water? (assume room temperature is 27oC)

Solubility Curves II

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For the following problems, SHOW ALL WORK!!! Remember that all numbers MUST have units!!!!!

1. At 45oC, how many grams of potassium nitrate would dissolve in 400g of water?

2. If a saturated solution at 20oC contained 20g of ammonia, how much water is present?

3. If you put 20g of potassium nitrate into 200g of water at 10oC, what type of solution do you have?

4. How many grams of water would it take to dissolve 80g of NaCl at 40oC?

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Molarity Practice

1. What is the molarity of a solution with 8.0 moles of HCl and 4.0 liters of total solution?

2. What is the volume of a solution that contains 5.9 moles of HCl and is a molarity of 6.7M?

3. How many moles of HCl are in a 6.0M solution that is 2.0 liters?

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4. How many moles of HCl are in a 6.0M solution that is 20ml?

5. What is the molarity of a solution with 7.9 moles of NaOH and 500ml?

6. What is the molarity of a solution with 6.89 grams of NaOH and 450mL of total solution?

7. If you dissolve 100 grams of Ca(OH)2 in 500 mL of total solution, what is the molarity of the solution?

8. If you dissolve 25 grams of CuCl2 in 600mL of total solution, what is the molarity of the solution?

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9. Describe how you would make 2.0L of a 2.0M solution of KCl?

Concentrations

1. Calculate the molarity of 500ml of solution containing 32 grams of naphthalene, C10H8, dissolved in benzene, C6H6.

2. How many grams of sodium hydroxide, NaOH, are needed to prepare one liter of a 2.00M solution?

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3. Determine the molarity of a solution containing 16 grams of ammonium nitrate, NH4NO3, in 500 ml of solution.

4. In what volume of solution must 27 grams of zinc chloride, ZnCl2, be dissolved to prepare 0.1M solution?

5. Calculate how many grams of sodium nitrate, NaNO3, must be dissolved in water to produce 250 ml of a 1.6 molar solution.

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STATIONName of Substance

FORMULAFORMULAWEIGHT

(F.W.)

SOLUTION INFORMATIONMOLARITY

MVOLUME OF SOLUTION

GRAMS OF SOLUTE

1 Sodium thiosulfate pentahydrate

0.50 2.0 L

2 Potassium chlorate 1.0 525 cm3

3 Ammonium chloride 0.30 250 cm3

4 Calcium hydroxide 2.2 125 ml

5 Zinc sulfate heptahydrate

3.0 2.5 L

6 Potassium chloride 0.50 3.00 L

7 Iron(II) sulfate heptahydrate

1.0 175 cm3

8 Calcium carbonate 0.80 48 g

9 Sodium bicarbonate 3.1 1.25 L

10 Copper (II) sulfate pentahydrate

0.225 L 15 g

11 Calcium chloride 175 cm3 150 g

12 Lithium carbonate 2.0 130 g

Solution Preparation Practice1) Move around the lab and collect formula weight and formula information from each sample. This is found on the bottle.2) Move back to your desk with your lab partner and complete the blank spaces under “Solution Information”3) Listen to your teacher and take notes on the next page on how to prepare one of the solutions.

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Calculations for Solution Preparation Practice

How to prepare a solution.Take notes using text and/or drawings.

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Dilution Delusion- Solution Confusion

Purpose

1. To practice mixing a Molar solution2. To mathematically determine the molar (M) concentration of a solution.3. To quantitatively determine the mass of a solid in solution- in the lab.

Directions

1. Go to your lab station- read the information sheet at the station and, working with the pair across from you, calculate how much solute you need to make the desired volume and molarity of the solution. Write down your plan.

2. Go across the room and confirm the calculations of the station next to yours. If incorrect, challenge that group, and correct the calculations if necessary.

3. Return to your station and prepare your solution.

4. When all 6 stations have prepared their solutions- dump your solution into the large “common” flask.

5. Answer the following questions about the “common” solution.a. By calculation, what is the Molar concentration (M) of the “common” solution?

Show your work.

b. Calculate how many grams of salt would be in 5 ml of the “common” solution. Show your work.

6. Withdraw 5 ml of the “common” solution and experimentally determine how many grams of salt is in the solution. (If you need special equipment ask your teacher.)

7. Compare your experimental results with your calculate results in step 5a by doing a percent error. (Actual/theoretical)x100

Conclusion

Summarize what you have learned from this lab experience. Describe the salt recovery technique that you used. How efficient was it? What are two sources of error?

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STATION 1

Volume: 125 mlM: 0.15

Mass needed ____________g

STATION 6


Mass needed_____________g

STATION 3



STATION 2



STATION 5



STATION 4

Volume 110 mlM: 0.75

Mass needed _____________g

COMMON

SOLUTION

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Analysis of Kool-Aid

IntroductionThe Kool-Aid that you make when you follow the directions on the back of the package

has a 2.0M dye concentration. In this lab we are going to determine if Kool-Aid Jammers that you buy at the store have the same dye concentration. If not we want to determine the concentration (molarity) of the Kool-Aid Jammers.

We will start by making up four different concentrations of Kool-Aid( 2M, 1M, 0.5M, 0.25M). We will then use a colorimeter to analyze the samples and measure how much light is absorbed by the solution. The absorbance values will then be recorded and plotted on a graph versus the dye concentration to produce a standard curve. Using this standard curve and the absorbance value of the Kool-Aid Jammer, you can determine the Jammer’s dye concentration.

ProcedurePreparing the Kool-Aid Stock Solution (2.0M)

1. Measure out the amount of Kool-Aid powder you calculated in the first pre-lab questions and place it in a 250mL beaker.

2. Put about 25-50mL of tap water in the beaker and dissolve the powder by mixing with a glass stirring rod. Carefully pour this solution into a 100mL graduated cylinder.

3. Fill the graduated cylinder up to the 100mL line with water from the squirt bottle.4. Pour the solution back into the beaker. Stir to make sure the Kool-Aid is completely dissolved.5. Pour a sample of the 2.0M Kool-Aid into a clean test tube and place it in your test tube rack.

Preparing the Diluted Kool-Aid Solutions (1.0M, 0.5M, 0.25M)6. Now you will make three dilutions from this stock solution.

a. Use the calculations from pre-lab question #2 to determine how much of the 2.0M Kool-Aid to add to make a 10mL solution of 1.0M Kool-Aid.

b. Add the correct amount of 2.0M Kool-Aid to a 10mL graduated cylinder. Use a medicine dropper to help you get the exact amount.

c. Fill the graduated cylinder up to the 10mL line using the squirt bottle of water.d. Pour this sample into a clean test tube and place it in your test tube rack. Remember

the concentration of this sample.7. Repeat steps a-d to make the 0.5M and 0.25M Kool-Aid samples.

Collecting Absorbance Data from the ColorimeterYour colorimeter is already calibrated and ready to use.

8. Be sure the knob on the colorimeter is turned to Blue (470nm). If it is not, turn the knob now.9. Fill an empty cuvette ¾ full with the 2.0M Kool-Aid sample.10. Place this sample into the colorimeter so the clear sides line up with the white line. Close the

door and record the absorbance value on the screen in your data table.11. Clean out the cuvette with distilled water and place the next sample (1.0M Kool-Aid) into the

cuvette (or an extra if provided). Place this in the colorimeter and record the absorbance value. Repeat with the 0.5M and 0.25M Kool-Aid solutions.

12. Finally fill the cuvette with the Kool-Aid Jammer sample and record the absorbance value. Clean all your glassware and put your materials back.

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Pre Lab Questions (go in lab notebook)

Purpose Statement:

Pre-Lab Questions:1. We need to make 100mL of a 2M Kool-Aid Solution.

Remember:Molarity =

If Kool-Aid powder has a molar mass of 1 mol=40 g, calculate the amount in grams of powder needed.

2. Then we want to make a 10mL sample of 1M Kool-Aid solution from the 2M stock Kool-aid solution. Use the formula M1V1=M2V2 to determine how much (volume in milliliters) of the 2M Kool-Aid you need to add.

3. Use a similar calculation to #2 to determine how much to make a 10mL sample of 0.5M from the 2.0M stock solution of Kool-Aid. How much (volume in milliliters) of the 2.0M Kool-Aid do you need?

4. Let’s do the calculation one more time. Make a 0.25M Kool-Aid solution using the 2.0M stock solution of Kool-Aid. How much (volume in milliters) of the stock solution do you need?

Hypothesis:Do you think the concentration of the Kool-Aid Jammer will be greater than, equal to or less than the concentration of Kool-Aid you make at home?

Data Table:Create a data table to record all of the measurements you will make in the lab.

Moles of soluteliters of total solution

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Post-Lab Data Analysis:1. Graph the absorbance versus Concentration of the samples. Then draw a best fit line.

This is your standard curve.

2. Place a circle of * on your standard curve that matches the absorbance value of the Kool-Aid Jammer. Based on your standard curve, what is the dye concentration of the Kool-Aid Jammer sample? Show your work on your graph.

3. What does the absorbance of a solution tell you about the solution?

4. Did the absorbance increase or decrease as the concentration got smaller? Why?

Conclusion:1. Compare the dye concentration of the Kool-aid jammer to the actual concentration that Kool-Aid

should be (based on how we are supposed to make it from the package).

2. If your concentrations were similar, explain why the Kool-Aid company would make the dye concentrations the same. OR If your concentrations were different, explain some possible reasons the Kool-Aid company would have a difference in the dye concentration of the Jammer and the solution concentration made from the package.

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Alka-Seltzer and Gas SolubilityIntroductionThe solubility of solids and liquids generally increases as the temperature increases. In the case of gases, however, this generalization is always wrong. What can Alka-Seltzer teach us about the effect of temperature on the solubility of a gas?

Concepts

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Gas Solubility Reversible reactions

Safety PrecautionsSodium hydroxide solution is a corrosive liquid. Use extreme caution when handling this solution as it can cause burns and blindness.

Materials (italicized materials YOU need to provide)Alka-Seltzer tabletBromthymol blue indicator, 0.04%, 10 mLSodium hydroxide solution, 1M, NaOH, 5mLTap waterIce bathBalanceBeakers, 250mL, 3 (I’ll provide 2)2 pipets

10mL graduated cylinderHot plateStirring rodTest tube rackTest tubes, 3ThermometerWeighing paper/dishes, 2

Procedure1. Add 200mL of water to each of three 250mL beakers. Place one beaker in an ice

bath, heat the second beaker on a hot plate, and allow the third to sit at room temperature.

2. Obtain two 1.0g samples of Alka-Seltzer tablets in a weighing dish.3. When the water on the hot plate has reached a temperature of 75-80oC, remove it

from the heat. Remove the cold water beaker from the ice bath at this time also.4. Add 3mL of bromthymol blue to each beaker. (The water should be blue-green,

indicating a neutral pH).5. Simultaneously drop the two Alka-Seltzer samples into the hot and cold beakers.

Observe and compare evidence of physical and chemical changes in each beaker.6. When the Alka-Seltzer tablets have fully dissolved, note the color and appearance of

the solution in each beaker.7. Measure the temperature of each solution, including the room temperature control,

and label three test tubes with the corresponding temperature.8. Using a graduated cylinder, remove a 25mL sample from each beaker, including the

room temperature control, and place the sample in the appropriately labeled test tube.

9. Using a pipet, add 1M sodium hydroxide solution drop-wise to the cold water mixture. Count the number of drops of NaOH that must be added to match the color of the room temperature control solution. Stir to swirl between drops to ensure thorough mixing.

10.Repeat step 9 using the hot water mixture, again comparing the color with that of the room temperature control.

DisposalAll solutions may be rinsed down the drain with excess water.

Post-Lab Questions

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1. Create a data table to record your data for this lab.

2. Compare the acidity of the cold water to the hot water. How do they compare and contrast?

3. Compare the solubility of each gas in the hot water and cold water. Verify your conclusion using data from the lab.

4. How might water temperature affect aquatic life?

5. What if the aquatic life lived downstream of dump-water from a nuclear power plant?

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That was a Killer Cup of Coffee: Using colorimetry to determine concentration of a poisonDetermine the concentration of cyanide in the solution

A Killer Cup of Coffee? GlobalTech Manager Dies

SOUTH PAINTER, Tuesday: It was a normal Morning at GlobalTech Industries until the mail boy discovered project manager Patrick Marchand dead in his cubicle, head on his desk. Mr. Marchand had died while writing an email, in a room full of people hard at work. An early examination of the crime scene yielded no clues.

Mr. Marchand was known to have a serious heart condition, and many signs pointed to cardiac arrest as the cause of his death. However, as police canvassed the office space, the distinct odor of bitter almonds was detected, and a vial containing a small amount of an unknown chemical was found discarded in a communal trash can.

Based on the bitter almond odor, police have tentatively identified the substance as cyanide. The existence of this possible poison has lead police to suspect foul play in Mr. Marchand’s death. The police have no leads.

LAB NOTES

Technician: Beverly Chin

-received vile containing 20 mL cyanide solution- concentration unknown-reacted syanide (CN-) solution with potassium polysulfide (K2Sx) to produce potassium thicyanate (KSCN)-reacted KSCN solution with iron(III)chloride (FeCl3) to produce iron(III)thiocyanate ion (FeSCN2+)-determination of amount of FeSCN2+ in reacted solution will allow estimation of concentration of CN- in original solution-included in package: FeSCN2+ solution of unknown concentration

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That was a Killer Cup of Coffee: Using colorimetry to determine concentration of a poison

Forensics Objective Use Beer’s Law to determine the concentration of Iron (III) thiocyanate (FeSCN2+) in an

unknown solution.

Science and Mathematics Objectives Use colorimetry to determine the concentration of a colored species in a solution Use a linear relationship to model Beer’s Law

Materials (for each group) Vernier colorimeter 2 cuvettes Distilled water 50 mL of prepared FeSCN2+ solution of known concentration 5 mL of FeSCN2+ solution with unknown concentration GOGGLES

Introduction:The colorimeter you will use today is a computer-interfaced probe designed to determine the concentration of a solution by analyzing its color intensity. Light will be absorbed by the solution. This is called absorbance. In general, absorbance is important because of its direct relationship with concentration according to Beer’s Law. You will make a graph of absorbance versus concentration of several different samples of known concentration. Then you will find the absorbance of an unknown solution, and, using the graph, determine its concentration.

Procedure

Part 1: Preparing the solutions

A fatal dose of FeSCN2+ is about 1.5 oz (equivalent to about three of four coffee creamers) or 0.105M

1. The five standard solutions, and the unknown have already been prepare for colorimetry.

REMEMBER:

Goggles MUST be worn at all times during this lab activity! CAUTION: Be careful not to ingest any solutions or spill any on your skin. Inform your teacher immediately in the event of an accident.

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- Cuvettes fill up FAST. Be careful not to spill. Use 1.5 pipettes to fill each cuvette.- Use two cuvettes for this lab. One with water for a blank and one for your standard

solutions. Rinse “standard cuvette” with the next solution two or three times before filling it and putting it in the colorimeter

- Handle a cuvette only by the edges or the ribbed sides.- All solutions should be free of bubbles. Lightly tap the cuvette on the table to move

bubbles out of the solution

Solution Concentrations

Test Tube FeSCN2+ Solution (mL) Distilled H2O (mL) Final Concentration of FeSCN2+(mol/L)

1 10 0 0.152 8 2 0.123 6 4 0.094 4 6 0.065 2 8 0.03

Part II: Collecting the Data1. The colorimeter is attached to the computer and the program is open.

2. Calibrate the Colorimeter (may be completed, check with your teacher)a. Click “Experiment” at the top of the screen and choose “Calibrate” towards to bottom and

choose the colorimeter.b. Place an empty cuvette in the cuvette slot of the Colorimeter. Make sure that one of the

transparent faces of the cuvette is pointing toward the white reference mark (match the line on the top of the cuvette with the white line on the colorimeter). Close the lid of the Colorimeter.

c. Turn the knob to “0% T”. When the voltage value shown on the computer monitor stabilizes, type “0” where it asks you to enter a value. Click “Keep.”

d. Set the wavelength of the Colorimeter to 470 nanometers (nm). This will set the Colorimeter’s light emitter and receiver to emit and record blue light.

e. Place a cuvette filled ¾ full with distilled water into the colorimeter.f. When the voltage value shown stabilizes, enter “100” for the value. Click “Keep.”

3. You are now ready to collect absorbance data for the five standard solutions.a. Rinse a cuvette two ro three times with the 0.15M solution.b. Fill a cuvette ¾ full (1.5 pipettes) with solution 0.15M. Place a lid on the cuvette.c. Place the cuvette into the colorimeter. Be sure the ribbed edges face you and away from

you.d. Select “Collect” to begin collecting data.

e. When the value displayed on the calculator screen has stabilized, select “keep” to record the absorbance of the first standard. DO NOT CLICK STOP.

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f. The program will ask you to enter a value. Enter the concentration of FeSCN2+ in the solution (from the table above). Select OK to store this absorbance-concentration data pair.

g. Write the absorbance value, rounded to the nearest 0.001, for each standard solution in your Evidence Record.

h. Repeat steps 3a-3g for each of the remaining standards (0.12, 0.09, 0.06 and 0.03) Be sure to enter the correct concentration for each standard in step 3d.

4. Select STOP when you have finished collecting data for all the standards.

5. Logger Pro should display a graph showing concentration of FeSCN2+ on the x-axis and absorbance of blue light on the y-axis.

6. Rinse the cuvette two or three times with the unknown solution. Fill the cuvette ¾ full with the unknown solution. Place the cuvette with the unknown solution in the Colorimeter. Monitor the absorbance value displayed on the screen. When this value has stabilized, round it to the nearest 0.001 and write it in your Evidence Record.Note: There’s no need to click “collect” or “keep” for the unknown.

7. Discard the remaining solutions according to your teacher.

Part III: Analyzing the Data

8. To determine the concentration of FeSCN2+ in the unknown solution, you will use the graph of absorbance vs. concentration for your standard solutions and fit a straight line to the points. Then use the absorbance value of the unknown to estimate its concentration of FeSCN2+.

9. Click the box in the tool bar that says “R=” in it. It’s to the left of the “LabPro” box.a. This will put a linear fit line through your data and display a box to the right of your

graph.b. The equation for the straight line is y=mx+b, where y is absorbance, x is concentration,

m is the slope, and b is the y-intercept. The correlation coefficient, R, indicates how well the data points match the line. A value of 1.00 indicates a perfect fit.

c. Record the values of m, b, and r in the Evidence Record.

10. The linear relationship (straight line) between absorbance and concentration is known as Beer’s Law.

11.Move the mouse along the straight line that was drawn. The values are at the bottom in this format (x, y). Move the mouse along the line until the Y value reads the absorbance of the unknown that you recorded. BE SURE THE CURSOR IS ON THE LINE.

a. The corresponding X value is the estimated concentration of FeSCN2+ in the unknown solution. Write this value in the Evidence Record.

Data Table and post-lab discussion questions will be provided by your teacher.

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