Duong Minh Khoi
Ms. Abigail Reed
AP Chemistry, P5
10/21/19
Fundamentals of Calorimetry
Lab date: 10/25/19
Purpose: Determining the specific heat capacity of the calorimeter, the enthalpy of the solution for calcium
chloride and ammonium chloride.
Background
Calorimetry is the science of measuring heat. Plenty chemical and physical transformations involve energy
transfer in the form of heat which is usually taken away from the water in reactions occurring in aqueous
solutions.
A calorimeter is an apparatus that is insulated and prevents heat from flowing into or out of the system.
The heat transfer or change in enthalpy in reactions can be calculated following equation:
q reaction =−(m∗c∗∆T )
The specific heat capacity of water is 4.186 J/(oC x g).
If a process increases the solution temperature it is exothermic (negative ∆ H ), whereas if a process
decreases the solution temperature it is endothermic (positive ∆ H ).
Pre-laboratory Questions
1. What is calorimetry? What is a calorimeter?
Calorimetry is the science of measuring heat.
A calorimeter is an apparatus that is insulated and prevents heat from flowing into or out of the system.
2. What are the appropriate units for each of the variables in the equation q=cm ∆ T ?
q stands for heat (J)
c stands for the specific heat capacity (J/(oC x g))
m stands for mass (g)
∆ T stands for the change in temperature (oC)
3. Read the laboratory procedures and then diagram them, using illustrations and/or a flow chart to
describe the steps. Ensure that your diagrams are labeled with quantities and descriptions.
Procedure
1. One foam cup was nested inside another and then both cups were placed inside a 400-mL beaker. This is
the coffee cup calorimeter for measuring changes in temperature.
2. 50.0 mL room-temperature water was measured with a graduated cylinder and was poured into a clean, dry
coffee cup calorimeter. This will be considered the cold water.
3. The lid was placed on the calorimeter, pulling back the tab to form an opening for a thermometer.
4. The temperature of the water in the calorimeter was measured and recorded (to ± 0.1 oC) as the initial
temperature of cold water.
5. 100.0 mL was placed in a clean, dry beaker.
6. The water in the beaker was heated until it was at least 30oC warmer than the cold water.
7. 50.0 mL of this warm water was poured into the remaining foam cup (not part of the calorimeter).
8. The temperature of the warm meter was measured and recorded (to ± 0.1 oC) as the initial temperature of
the warm water.
9. Time must begin to be monitored immediately by one group member as the water is combined in the next
step.
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, 10. The lid was removed, and the warm water was poured into the cold water in the calorimeter. The lid and
thermometer were placed on the calorimeter.
11. On the Data Table, the first temperature was recorded 10 seconds after combining the two water samples
and then every 10 seconds for 90 seconds.
12. The water was discarded, and the calorimeter was thoroughly dried
Determining the enthalpy of solution for calcium chloride
1. 100.0 mL water was measured with a graduated cylinder and was poured into the calorimeter.
2. The lid was placed on the calorimeter and the tab was opened to insert a thermometer.
3. The water was stirred with the thermometer, monitoring the temperature until it is stable. This
temperature was recorded (to ± 0.1 oC) in the Data Table as the initial temperature.
4. 5.00 g calcium chloride (CaCl2) was measured. The exact value used in the Data Table was recorded.
5. The lid was removed and the 5.00 g CaCl2 was added to the calorimeter and was stirred. The lid and
thermometer were replaced.
6. Continue to stir and the temperature was monitored for 2 minutes. The highest temperature obtained was
recorded (to ± 0.1 oC) in the Data Table as the final temperature.
7. The solution was discarded as directed by the teacher and the inner cup was rinsed. The calorimeter
apparatus was thoroughly dried before reusing.
8. Steps 1 – 8 were repeated with 10.00g CaCl2 and 15.00g CaCl2.
Determining the enthalpy of solution for ammonium chloride
1. 100.0 mL water was measured with a graduated cylinder and was poured into the calorimeter.
2. The lid was placed on the calorimeter, pulling back the tab to form an opening for a thermometer.
3. The water was stirred with the thermometer, monitoring the temperature until it is stable.
4. 5.00 g ammonium chloride (NH4Cl) was measured and added to the calorimeter and stirred.
5. Continue to stir and the temperature was monitored for 2 minutes. The lowest temperature obtained was
recorded (to ± 0.1 oC) in the Data Table as the final temperature.
6. The solution was discarded as directed by the teacher, and the calorimeter was thoroughly rinsed and
dried.
7. Steps 1 – 6 were repeated with 10.0 g NH4Cl and then with 15.0 g.
Data Tables
Time (seconds) Temperature (oC) Initial temperature of cold water (oC) 20.60
10 44.10 Initial temperature of warm water
20 43.50 (oC) 56.60
30 43.40 Average temperature (oC) 38.60
40 43.30 Temperature at 0 seconds (oC) 43.90
50 43.30 Heat lost by the water (J) 2218.58
60 43.20 Heat capacity of the calorimeter
70 43.00 (J/oC) 95.22
80 43.00
90 42.90
Calcium chloride Ammonium chloride
5g 10 g 15 g 5g 10 g 15 g
CaCl2 CaCl2 CaCl2 NH4Cl NH4Cl NH4Cl
Mass of water (g) 100.00 100.00 100.00 100.00 100.00 100.00
Mass of salt (g) 4.99 10.09 15.00 5.00 10.01 15.00
Moles of salt (g x mol/g) 0.04 0.09 0.14 0.09 0.19 0.28
Initial temperature (oC) 20.70 20.70 20.90 20.80 20.90 20.70
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Ms. Abigail Reed
AP Chemistry, P5
10/21/19
Fundamentals of Calorimetry
Lab date: 10/25/19
Purpose: Determining the specific heat capacity of the calorimeter, the enthalpy of the solution for calcium
chloride and ammonium chloride.
Background
Calorimetry is the science of measuring heat. Plenty chemical and physical transformations involve energy
transfer in the form of heat which is usually taken away from the water in reactions occurring in aqueous
solutions.
A calorimeter is an apparatus that is insulated and prevents heat from flowing into or out of the system.
The heat transfer or change in enthalpy in reactions can be calculated following equation:
q reaction =−(m∗c∗∆T )
The specific heat capacity of water is 4.186 J/(oC x g).
If a process increases the solution temperature it is exothermic (negative ∆ H ), whereas if a process
decreases the solution temperature it is endothermic (positive ∆ H ).
Pre-laboratory Questions
1. What is calorimetry? What is a calorimeter?
Calorimetry is the science of measuring heat.
A calorimeter is an apparatus that is insulated and prevents heat from flowing into or out of the system.
2. What are the appropriate units for each of the variables in the equation q=cm ∆ T ?
q stands for heat (J)
c stands for the specific heat capacity (J/(oC x g))
m stands for mass (g)
∆ T stands for the change in temperature (oC)
3. Read the laboratory procedures and then diagram them, using illustrations and/or a flow chart to
describe the steps. Ensure that your diagrams are labeled with quantities and descriptions.
Procedure
1. One foam cup was nested inside another and then both cups were placed inside a 400-mL beaker. This is
the coffee cup calorimeter for measuring changes in temperature.
2. 50.0 mL room-temperature water was measured with a graduated cylinder and was poured into a clean, dry
coffee cup calorimeter. This will be considered the cold water.
3. The lid was placed on the calorimeter, pulling back the tab to form an opening for a thermometer.
4. The temperature of the water in the calorimeter was measured and recorded (to ± 0.1 oC) as the initial
temperature of cold water.
5. 100.0 mL was placed in a clean, dry beaker.
6. The water in the beaker was heated until it was at least 30oC warmer than the cold water.
7. 50.0 mL of this warm water was poured into the remaining foam cup (not part of the calorimeter).
8. The temperature of the warm meter was measured and recorded (to ± 0.1 oC) as the initial temperature of
the warm water.
9. Time must begin to be monitored immediately by one group member as the water is combined in the next
step.
This study source was downloaded by 100000858936669 from CourseHero.com on 01-12-2023 01:59:07 GMT -06:00
https://www.coursehero.com/file/52651566/Fundamentals-of-Calorimetrydocx/
, 10. The lid was removed, and the warm water was poured into the cold water in the calorimeter. The lid and
thermometer were placed on the calorimeter.
11. On the Data Table, the first temperature was recorded 10 seconds after combining the two water samples
and then every 10 seconds for 90 seconds.
12. The water was discarded, and the calorimeter was thoroughly dried
Determining the enthalpy of solution for calcium chloride
1. 100.0 mL water was measured with a graduated cylinder and was poured into the calorimeter.
2. The lid was placed on the calorimeter and the tab was opened to insert a thermometer.
3. The water was stirred with the thermometer, monitoring the temperature until it is stable. This
temperature was recorded (to ± 0.1 oC) in the Data Table as the initial temperature.
4. 5.00 g calcium chloride (CaCl2) was measured. The exact value used in the Data Table was recorded.
5. The lid was removed and the 5.00 g CaCl2 was added to the calorimeter and was stirred. The lid and
thermometer were replaced.
6. Continue to stir and the temperature was monitored for 2 minutes. The highest temperature obtained was
recorded (to ± 0.1 oC) in the Data Table as the final temperature.
7. The solution was discarded as directed by the teacher and the inner cup was rinsed. The calorimeter
apparatus was thoroughly dried before reusing.
8. Steps 1 – 8 were repeated with 10.00g CaCl2 and 15.00g CaCl2.
Determining the enthalpy of solution for ammonium chloride
1. 100.0 mL water was measured with a graduated cylinder and was poured into the calorimeter.
2. The lid was placed on the calorimeter, pulling back the tab to form an opening for a thermometer.
3. The water was stirred with the thermometer, monitoring the temperature until it is stable.
4. 5.00 g ammonium chloride (NH4Cl) was measured and added to the calorimeter and stirred.
5. Continue to stir and the temperature was monitored for 2 minutes. The lowest temperature obtained was
recorded (to ± 0.1 oC) in the Data Table as the final temperature.
6. The solution was discarded as directed by the teacher, and the calorimeter was thoroughly rinsed and
dried.
7. Steps 1 – 6 were repeated with 10.0 g NH4Cl and then with 15.0 g.
Data Tables
Time (seconds) Temperature (oC) Initial temperature of cold water (oC) 20.60
10 44.10 Initial temperature of warm water
20 43.50 (oC) 56.60
30 43.40 Average temperature (oC) 38.60
40 43.30 Temperature at 0 seconds (oC) 43.90
50 43.30 Heat lost by the water (J) 2218.58
60 43.20 Heat capacity of the calorimeter
70 43.00 (J/oC) 95.22
80 43.00
90 42.90
Calcium chloride Ammonium chloride
5g 10 g 15 g 5g 10 g 15 g
CaCl2 CaCl2 CaCl2 NH4Cl NH4Cl NH4Cl
Mass of water (g) 100.00 100.00 100.00 100.00 100.00 100.00
Mass of salt (g) 4.99 10.09 15.00 5.00 10.01 15.00
Moles of salt (g x mol/g) 0.04 0.09 0.14 0.09 0.19 0.28
Initial temperature (oC) 20.70 20.70 20.90 20.80 20.90 20.70
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