Calorimetry Lab Student Expolartion sheet 1 PDF

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Lab Work Calorimetry Lab Student Expolartion sheet 1...

Description

Name: ______________________________________

Date: ________________________

Student Exploration: Calorimetry Lab Unit 1: Summative Criterion B ,C &D

Name/Group #:……………………… Grade and Section: ………………………………………

MYP Year Level: 5

Criteria

Name of Criterion:

Highest Level

Criterion (B)

Inquiring and Designing

8

Criterion (C)

Criterion (D)

Processing and Evaluating Reflecting on the impacts

Date:

Your Level

8

8

of science

Subject/Unit

Thermochemist ry

Statement of Inquiry

Recognizing and explaining patterns and relationships inherent in the organization of information allow predictions that can be verified by evidence.

1

Global Context

Scientific and technical innovation

Key Concept

Relationship

Command Terms Used Command Term

Definition

Apply

Use knowledge and understanding in response to a given situation or real circumstances. Use an idea, equation, principle, theory or law in relation to a given problem or issue.

Describe

Give a detailed account or picture of a situation, event, pattern or process.

Explain

Give a detailed account including reasons and causes Use knowledge and understanding to recognize trends and

Interpret Outline State

draw conclusion from given information. Give a brief account or summary. Give a specific name, value or other brief answer without explanation or calculation.

I. Purpose: Calorimetry is used to measure the amount of thermal energy transferred in a chemical or physical process. This requires careful measurement of the temperature change that occurs during the process and the masses of the system and surroundings. The goal of this lab is to determine the specific heat of an unknown metal.

II. Background information: Plants utilize sunlight during photosynthesis to convert carbon dioxide and water into glucose (sugar) and oxygen. This glucose has energy stored in its chemical bonds that can be used by other organisms. This stored energy is released whenever these chemical bonds are broken in metabolic processes such as cellular respiration. Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Cellular respiration is the general term, which describes all metabolic reactions involved in the formation of usable energy from the breakdown of nutrients. In living organisms, the "universal" source of energy is adenosine triphosphate (ATP). Carbohydrates, lipids (fats), and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved. Marathon runners eat a large plate of pasta the night before a competition because pasta is a good source of energy, or fuel for the body. All foods contain energy, but the amount of potential energy stored will vary greatly depending on the type of food. Moreover, not all of the stored energy is available to do work. When we eat food, our bodies convert the stored energy, known as calories, to chemical energy, thereby allowing us to do work. A calorie is the amount of heat (energy) required to raise the temperature of 1 gram (g) of water 1 degree Celsius (°C). The density of water is 1 gram per milliliter (1g/ml); therefore, 1 g of water is equal to 1 ml of water. When we talk about caloric values of food, we refer to them as Calories (notice the capital “C”), which are actually kilocalories. There are 1000 calories in a kilocalorie. So in reality, a food item that is listed as having 38 Calories has 38,000 calories. Calories are a way to measure the energy you get from the food you eat. Just as pasta can provide a runner energy to run a marathon, a tiny peanut contains stored energy that can be used to heat a container of water. For this lab exercise, you will indirectly measure

2018

the amount of Calories in a couple of food items using a calorimeter. A calorimeter (calor = Latin for heat) is a device that measures the heat generated by a chemical reaction, change of state, or formation of a solution. There are several types of calorimeters but the main emphasis of all calorimeters is to insulate the reaction to prevent heat loss. We will be using a homemade calorimeter modeled after a constant-volume calorimeter. A particular food item will be ignited, the homemade calorimeter will trap the heat of the burning food, and the water above will absorb the heat, thereby causing the temperature (T) of the water to increase. By measuring the change in temperature (∆T) of a known volume of water, you will be able to calculate the amount of energy in the food tested.

Vocabulary: calorie, calorimeter, joule, specific heat capacity

Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. The Latin word calor means “heat,” and meter comes from the Greek word meaning “to measure.” What do you think a calorimeter does? ________________________________ _________________________________________________________________________

2. Where have you heard the word calorie before? What do you think a calorie is? _________ _________________________________________________________________________

Gizmo Warm-up

A calorimeter is an insulated container filled with a liquid, usually water. When a hot object is placed in the calorimeter, heat energy is transferred from the object to the water and the water heats up. Calorimeters can be used to find a substance’s specific heat capacity. You will use the Calorimetry Lab Gizmo to determine the specific heat capacities of various substances. 1. On the SIMULATION pane, select Copper. Use the slider to set its Mass to 200 g. Set the Water mass to 200 g. Check that the Water temp is set to 30.0 °C and the copper’s Temp is 90 °C. Select the GRAPH tab, and click Play ( ). A.

What was the Final temperature of the copper and the water? _________________

B.

How much did the temperature of the copper change? ________________________

C.

How much did the temperature of the water change? _________________________

2. Specific heat capacity can be described as a substance’s resistance to temperature changes. Which substance has a greater specific heat capacity, copper or water? Explain. _________________________________________________________________________ _________________________________________________________________________

Activity A:

Get the Gizmo ready:

Heat transfer

 Click Reset (

).

Question: What factors determine how heat energy transfers between objects? 1. Predict: In the Gizmo warm-up, you saw how 200 g of 90 °C copper transfers heat to 200 g of 30.0 °C water. A. How do you think increasing the water’s mass would affect the final temperature? ___________________________________________________________________ ___________________________________________________________________ B. How do you think decreasing the copper’s mass would affect the final temperature? ___________________________________________________________________ ___________________________________________________________________ C. How do you think increasing or decreasing the copper’s initial temperature would affect the final temperature? ____________________________________________ ___________________________________________________________________

2. Collect data: Use the Gizmo to determine the final temperature for each set-up listed below. Record your results in the tables. In the first table, you experiment with changing the water’s mass. In the second table, you change the copper’s mass. In the third table, you change the initial temperature of the copper. The first row of each table has been completed for you. Copper

Water

Initial Temp. (°C)

Mass (g)

Initial Temp. (°C)

Mass (g)

Final Temp. (°C)

90 °C

200 g

30.0 °C

200 g

34.96 °C

90 °C

200 g

30.0 °C

2,000 g

90 °C

200 g

30.0 °C

200 g

90 °C

20 g

30.0 °C

200 g

90 °C

200 g

30.0 °C

200 g

100 °C

200 g

30.0 °C

200 g

50 °C

200 g

30.0 °C

200 g

3.

4.

34.96 °C

5.

(Activity A continued on next page)

34.96 °C

Activity A (continued from previous page) 3. Analyze: For each factor listed in the chart below, explain how the final temperature was changed and why you think that change occurred. A. What was the effect of increasing the water’s mass? _________________________ ___________________________________________________________________ B. What was the effect of decreasing the copper’s mass? _______________________ ___________________________________________________________________ C. What was the effect of changing the initial temperature of the copper? ___________ ___________________________________________________________________ ___________________________________________________________________

4. Draw conclusions: The amount that the water’s temperature increases depends on the mass of the water and the amount of heat energy in the copper. A. How does changing the initial mass of the copper affect how much heat energy it has? _______________________________________________________________ ___________________________________________________________________ B. How does changing the initial temperature of the copper affect how much heat energy it has? _______________________________________________________ ___________________________________________________________________

5. Apply: Many gyms and health clubs have steam saunas, which are small steam-filled rooms. Traditionally, steam saunas have a container of heated rocks. A small ladle of water is poured on the rocks in order to make the steam. A. Use what you have learned so far about heat transfer to explain how hot rocks can be used to make steam? _______________________________________________ ___________________________________________________________________ B. Why do you think only a small ladle-full of water is poured on the rocks at one time? ___________________________________________________________________ ___________________________________________________________________

Activity B: Specific heat

Get the Gizmo ready:  Click Reset.  Deselect Copper, and select Granite.

Question: How can you compare the specific heat capacities of various substances? 1. Explain: How do you think you can use the calorimeter to compare the specific heat capacities of the substances listed on the Gizmo? _________________________________ _________________________________________________________________________ _________________________________________________________________________

2. Predict: Which substance do you think will have the highest specific heat capacity? Why? _________________________________________________________________________

_________________________________________________________________________

3. Experiment: Use the Gizmo to determine the final temperature for each set-up listed below. Record your results in the table. The first row has been completed for you. Substance

Substance initial temp. (°C)

Substance mass

Water initial temp. (°C)

Water mass

Final temp. (°C)

Copper

90 °C

200 g

30.0 °C

200 g

34.96 °C

Granite

90 °C

200 g

30.0 °C

200 g

Lead

90 °C

200 g

30.0 °C

200 g

4. Analyze: Of the three substances, which caused the largest temperature change in the water? What does this indicate about its relative specific heat capacity? ________________ _________________________________________________________________________

5. Interpret: Remember that specific heat capacity is a measure of a substance’s resistance to temperature change. The more resistant a substance is to temperature change, the higher is its specific heat capacity. Rank the three substances in order of their specific heat capacities, from highest to lowest.

_________________________________________________________________________

(Activity B continued on next page)

Activity B (continued from previous page) 6. Predict: How do you think the specific heat capacity of ice will compare to that of copper, granite, and lead? __________________________________________________________ _________________________________________________________________________

7. Experiment: Deselect Lead, and select Ice. Use the default values for Temp (-30 °C) and Mass (50 g). Set the Water temp to 60 °C and the Water mass to 200 g. Click Play. A. What was the final temperature? _________________________________________ B. What do you think is happening when the ice line on the graph is at 0 °C for a long period of time? Why do you think the line disappears after that? ________________ ___________________________________________________________________ C. How much of a temperature change did the water experience? _________________ D. How does this change in the water’s temperature compare to the change caused by the other substances you tested? ________________________________________

8. Extend your thinking: A lot of energy is needed to heat a substance with a high specific heat capacity. However, even more energy is needed to cause a phase change (such as the melting of ice). Click Reset. Set the ice’s Temp to -100 °C and its Mass to 50 g. Set the Water temp to 50 °C and Water mass to 200 g. Click Play. A. What was the final temperature? _________________________________________ B. Do you think all the ice melted? Explain. ___________________________________ ___________________________________________________________________ C. Look at the GRAPH. The graph shows two separate stages: the heating of the ice and then the melting of the ice. How much did the water’s temperature change while the ice was heating? How much did it change while the ice was melting? ___________________________________________________________________ ___________________________________________________________________ D. How did this experiment demonstrate ice’s high specific heat capacity? __________ ___________________________________________________________________

___________________________________________________________________

Activity C: Calculating specific heat

Get the Gizmo ready:  Click Reset.

Introduction: The specific heat capacity of a substance is the amount of energy needed to change the temperature of that substance by 1 °C. Specific heat capacity can be calculated using the following equation: q = mc∆T In the equation q represents the amount of heat energy gained or lost (in joules), m is the mass of the substance (in grams), c is the specific heat capacity of the substance (in J/g °C), and ∆T is the temperature change of the substance (in °C). Goal: Calculate the specific heat capacities of copper, granite, lead, and ice. 1. Solve: When you mix two substances, the heat gained by one substance is equal to the heat lost by the other substance. Suppose you place 125 g of aluminum in a calorimeter with 1,000 g of water. The water changes temperature by 2 °C and the aluminum changes temperature by –74.95 °C. A.

Water has a known specific heat capacity of 4.184 J/g °C. Use the specific heat equation to find out how much heat energy the water gained (q). ___________________________________________________________________

B.

Assume that the heat energy gained by the water is equal to the heat energy lost by the aluminum. Use the specific heat equation to solve for the specific heat of aluminum. (Hint: Because heat energy is lost, the value of q is negative.) ___________________________________________________________________

Aluminum’s accepted specific heat value is 0.900 J/g °C. Use this value to check your work.

2. Calculate: Use the Gizmo to mix 200 g of copper at 100 °C with 1,000 g of water at 20 °C. A. What is the final temperature? ___________________________________________ B. Calculate the temperature change of each substance by subtracting the initial temperature from the final temperature. ∆Twater: __________ C.

∆Tcopper: __________

How much heat energy (q) did the water gain? ______________________________

D.

Now solve for the specific heat (c) of copper: _______________________________

(Activity C continued on next page) Activity C (continued from previous page) 3. Calculate: Use the Gizmo to mix 200 g of granite at 100 °C with 1,000 g of water at 20 °C. A. What is the final temperature? ___________________________________________ B. Calculate the temperature change of each substance by subtracting the initial temperature from the final temperature. ∆Twater: __________

∆Tgranite: __________

C. How much heat energy (q) did the water gain? ______________________________ D. Now solve for the specific heat (c) of granite: _______________________________ E. Repeat steps A through D to find the specific heat (c) of lead: __________________

4. Challenge: Use the specific heat capacity that you calculated for granite to determine how many grams of granite at the initial temperature of 80 °C must mix with 3,000 g of water at the initial temperature of 20 °C to result in a final system temperature of 20.45 °C. (Hint: Start by calculating how much heat energy is needed to change the water’s temperature by 0.45 °C). Show your work. Use the Gizmo to check your answer.

Mass of granite = __________

5. Extend your thinking: In addition to calculating specific heat capacities, some calorimeters can be used to determine how much energy is in food. The energy in food is usually expressed in calories or kilocalories (Calories). A calorie is the amount of energy needed to change the temperature of 1 g of water by 1 C. There are 1,000 calories in a Calorie. A. How many joules are in 1 calorie? (The specific heat of water is 4.184 J/g °C.) ___________________________________________________________________ B. Suppose a snack bar is burned in a calorimeter and heats 2,000 g water by 20 °C. How much heat energy was released? (Hint: Use the specific heat equation.) Give your answer in both joules and calories.

___________________________________________________________________

C. How many kilocalories (Calories) does the snack bar contain? __________________...