released science inquiry task a cool investigation...

Released Science Inquiry Task

A Cool Investigation

2017

Grade 11

Student Test Booklet

Date: _____________________________________________________

Your Name: _______________________________________________

1

NECAP 2016-2017 Gr11 Science_Inquiry_Booklet

ScienceDirections:

You will be reading a story and analyzing the data provided to answer a set of questions. Read each question and thoroughly explain all of your answers. You may include labeled drawings or diagrams to help you answer the questions.

This Word Bank provides definitions for words used in this task. You may refer back to this page throughout the session.

Word Bank

Calorimetera device for measuring the heat released or absorbed during a chemical reaction, change of state, or formation of a solution

Compounda pure substance composed of two or more types of atoms bonded in specific ratios

Dissociationthe separation of an ionic compound into its individual charged ions by a chemical process, such as dissolving

Solution a substance dissolved in another substance to form a mixture

2NECAP 2016-2017 Gr11 Science_Inquiry_Booklet

A Cool Investigation

Eva arrives at science class with a swollen knee and a cold pack supplied by the school nurse. The pack instructions direct her to shake the pack for thirty seconds and then place the pack over a cloth or paper towel on the injured area for 20 minutes. The cold temperature will help reduce the swelling in her knee.

Instant Cold Pack

Coldpack

Papertowel

Eva’s classmates Victor and Jenna ask what makes the pack get cold. Eva thinks that a chemical change occurs inside the pack when she shakes it. Their teacher, Mr. Mayfield, tells the class that the pack is an example of one type of a chemical change the students have just studied called dissociation. He reminds the class that dissociation happens when an ionic compound dissolves and separates into individual ions.

Victor and Jenna identify the two cold pack ingredients as ammonium nitrate (NH4NO

3) and water (H

2O).

Mr. Mayfield draws the following diagram to model the dissociation of ammonium nitrate in water.

NH4NO3 NH4+ + NO3

–

ioniccompound

(in water)

→

ions dissolvedin water

The class discusses the compound and dissociation with Mr. Mayfield. The students conclude that when this compound dissolves in water it absorbs heat energy and cools the solution in the cold pack.

Victor gets an idea and asks, “Can we make our own cold pack by dissolving a compound in water to form a solution?”

“The class can design an investigation to find out,” Mr. Mayfield says. “What kind of solution would make the best cold pack?” he asks the students.

“It needs to get cold so it will absorb heat from the injury,” says Jenna.

“But not too cold!” Eva warns. “It needs to stop cooling just above zero degrees Celsius to avoid harming the skin.”

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“Those are both good observations,” says Mr. Mayfield. He tells the class that he can supply four compounds for the students to try in designing their cold packs. After some research and a discussion, the class agrees on this question to investigate:

Research Question:

When dissolved in 200 milliliters (mL) of water, what compound in the smallest amount will decrease the solution’s temperature to 1°C?

The class divides into four groups to investigate the research question. The four group names are Green, Blue, Orange, and Purple. The students decide that the groups will all follow the same procedures so that they can compare their results.

They realize that they will need to do two investigations to answer the research question.

In Investigation 1, each group will compare the same four compounds and choose the best compound to use for the cold pack.

In Investigation 2, the students will determine how much of the chosen compound is needed for the cold pack to reach a minimum of 1°C and no colder.

Mr. Mayfield tells the students that he will be providing them with samples of potassium nitrate, ammonium chloride, potassium chloride, and sodium nitrate. He instructs the students to do some background research on these compounds before they begin their investigations.


Background Research

Through their research, the students learn that each of the four compounds produces a different temperature change when it dissolves in water. They find data that show the standard measured laboratory values for the heat absorbed or released by compounds dissolving in water. Mr. Mayfield helps the students use these values to calculate the expected temperature change of 30 grams (g) of each of their compounds in 200 mL of water. Each group records these values in Table 1.

Table 1: Expected Temperature Change(30 g of compound dissolved in 200 mL water)

Name and FormulaExpected

Change (°C)

Potassium nitrate (KNO3) –12.4

Ammonium chloride (NH4Cl) –9.9

Potassium chloride (KCI) +8.3

Sodium nitrate (NaNO3) –8.7

Based on their research and calculations, the groups make the following predictions for the compound that will form the solution that reaches the lowest temperature:

• Green team: potassium nitrate

• Blue team: ammonium chloride

• Orange team: potassium chloride

• Purple team: sodium nitrate

Answer question 1 on page 10 in your Student Answer Booklet.

q Identify which group’s prediction about the solution that will reach the lowest temperature is supported by the data in Table 1. Describe how the data support this prediction.

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Investigation 1

In Investigation 1, each group will compare the same four compounds and choose the best compound to use for the cold pack.

Working together, the groups create the following list of materials they need for the first investigation.

Materials

• one simple calorimeter (thermometer, stirrer, cardboard lid, two foam cups)

• digital balance

• graduated cylinder

• two 1-liter bottles of 22°C water

• teacher-supplied samples of four compounds at 22°C

• paper towels

Next, the students use the foam cups, cardboard lid, stirrer, and thermometer to create the simple calorimeter shown in Diagram 1.

Diagram 1:Foam Cup Calorimeter

Thermometer

Stirrer

Cardboard lid

Two foam cups

200 mL waterand compoundsolution insideinner cup


Finally, the groups of students agree to follow the procedure below.

1. Be sure you are wearing all necessary protective equipment.

2. Measure 200 mL of water with the graduated cylinder. Add the water to the inner calorimeter cup.

3. Measure the water temperature with the thermometer and record it in your data table.

4. Measure 30 g of the compound on the digital balance and add it to the 200 mL of water in the calorimeter.

5. Place the cardboard lid on top of the calorimeter. Insert the stirrer and thermometer through the two lid holes.

6. Stir the solution continuously. Measure the temperature of the solution once each minute for the next four minutes. Record the temperatures observed in your data table.

7. Read and follow the disposal information Mr. Mayfield provides us with.

8. Ensure the cups, thermometer, lid, and stirrer are clean and wiped dry with paper towels.

9. Repeat steps 1–8 for the three remaining compounds.

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Each group conducts Investigation 1. After recording their results, the students share their data as a class and calculate the average temperatures for the solutions they made with each of the four compounds. Their results are shown in Tables 2–5.

Table 2: Potassium Nitrate (KNO3) Solution

Temperature (°C)

0min

2222222222

Group

AveragePurpleOrangeBlueGreen

1min

2min

3min

4min

14 12 10 1011 9 9 913 10 10 1017 14 12 1214 11 10 10

Table 3: Ammonium Chloride (NH4Cl–) Solution

Temperature (°C)

0min

2222222222

Group


1min

2min

3min

4min

12 10 10 1013 11 11 1112 11 10 1015 14 12 1213 12 11 11

Table 4: Potassium Chloride (KCI) Solution

Temperature (°C)

0min

2222222222

Group


1min

2min

3min

4min

28 29 30 3027 29 29 2929 30 30 3030 31 32 3229 30 30 30

Table 5: Sodium Nitrate (NaNO3) Solution

Temperature (°C)

0min

2222222222

Group


1min

2min

3min

4min

15 14 13 1314 13 13 1313 13 12 1218 16 15 1515 14 13 13



w Explain the most likely reason the students averaged the data from the four different groups. Support your explanation with evidence from the data in Tables 2–5.

Investigation 2

In Investigation 2, the students will determine how much of the chosen compound is needed for the cold pack to reach a minimum of 1°C and no colder.

The students will test four different amounts of potassium nitrate dissolved in 200 mL of water and record the temperature of the solutions each minute for the next four minutes.

The four groups conduct Investigation 2. Then the class averages the results of all four groups and records the data in Table 6, shown below.

Table 6: Average Potassium Nitrate (KNO3)Solution Temperatures (dissolved in 200 mL water)

Temperature (°C)

0min

22

22

22

22

1min

2min

3min

4min

8 7 7 6

3 3 2 2

0 –2 –2 –2

–5 –7 –7 –6

40

50

60

70

1

2

3

4

TestMass of

DissolvedKNO3 (g)

Answer questions 3 and 4 on page 11 in your Student Answer Booklet.

e Identify which group’s data show the greatest amount of experimental error during Investigation 1. Use Tables 2–5 to describe a possible experimental error that may have produced the specific data results.

r Use the specific data for each of the four compounds in Tables 2–5 from Investigation 1 to justify the students’ choice of potassium nitrate (KNO

3) as the best compound to use in a cold pack.

Based on the results of Investigation 1, the students choose potassium nitrate (KNO3) as the best compound

to use in the cold pack.

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t Create a graph that compares the average temperatures recorded by the class over four minutes in Table 6 during Investigation 2. Be sure to include all required elements of a graph and choose a scale that will clearly show the data.

After both investigations, Mr. Mayfield asks the students to discuss the results.

“We can make a cold pack that cools to 1°C using potassium nitrate,” Eva claims.

“I’m not so sure,” Victor wonders. “We didn’t match our final temperature of 1°C.”


y Explain why Eva’s claim that the class can make a cold pack that cools to 1°C using potassium nitrate is supported by the data in Table 6 even though Victor’s statement that the class did not match the final temperature of 1°C is true.

Planning Further Investigations

The students wonder how their results apply to making an actual cold pack.

“We know how potassium nitrate works in an insulated cup. Would we get the same results in an actual cold pack container that is not insulated?” Jenna asks.

The students want to perform an investigation with a potassium nitrate solution in a plastic bag instead of an insulated cup. They want to compare their results to the results from Investigation 2.


u Identify the three most important independent or controlled variables from Investigation 2 that would need to be used in the new investigation to be able to compare the results of both investigations. Explain why using these variables would allow a fair comparison.


“What if we needed a heat pack instead of a cold pack?” asked Victor.

Based on the data from the students’ investigations, a student predicts that a heat pack that reaches 40°C can be made from one of the four compounds.


i Explain how the evidence from both Investigation 1 and Investigation 2 support the prediction that a 40°C heat pack can be made from one of the four compounds.

released science inquiry task a cool investigation...

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