ScienceAges 16-18

Calorimetry & molar enthalpy change

Combine molar mass (n = m ÷ M) and calorimeter heat transfer to determine the magnitude of molar enthalpy of combustion |ΔH|. Review suitability for your learners before teaching.

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Worksheet StudioPractice pack · Ages 16-18

Calorimetry & molar enthalpy change

Take your time. Show your thinking.

1. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 50 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 50 g (M = 100 g/mol) · Heat Q = 50 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 3200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 20 g/mol) · Heat Q = 3200 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 120 g of a fuel (molar mass M = 60 g/mol) releases 1520 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 120 g (M = 60 g/mol) · Heat Q = 1520 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 640 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 480 g (M = 120 g/mol) · Heat Q = 640 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 20 g of a fuel (molar mass M = 20 g/mol) releases 460 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 20 g (M = 20 g/mol) · Heat Q = 460 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 200 g of a fuel (molar mass M = 100 g/mol) releases 1080 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 200 g (M = 100 g/mol) · Heat Q = 1080 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1400 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 120 g/mol) · Heat Q = 1400 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 100 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 16 g (M = 80 g/mol) · Heat Q = 100 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 80 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 40 g of a fuel (molar mass M = 40 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 40 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 50 g (M = 100 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 20 g/mol) · Heat Q = 2560 kJ → |ΔH| = Q ÷ n

12 questions · Seed 47 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 16-18

Calorimetry & molar enthalpy change

Answers and reasoning. Review before teaching.

1. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 50 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
100 kJ/mol
First find moles burned: n = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 50 kJ ÷ 0.5 mol = 100 kJ/mol.
2. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 3200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
800 kJ/mol
First find moles burned: n = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 3200 kJ ÷ 4 mol = 800 kJ/mol.
3. Complete combustion of 120 g of a fuel (molar mass M = 60 g/mol) releases 1520 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
760 kJ/mol
First find moles burned: n = 120 g ÷ 60 g/mol = 2 mol. Then |ΔH| = 1520 kJ ÷ 2 mol = 760 kJ/mol.
4. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 640 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
160 kJ/mol
First find moles burned: n = 480 g ÷ 120 g/mol = 4 mol. Then |ΔH| = 640 kJ ÷ 4 mol = 160 kJ/mol.
5. Complete combustion of 20 g of a fuel (molar mass M = 20 g/mol) releases 460 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
460 kJ/mol
First find moles burned: n = 20 g ÷ 20 g/mol = 1 mol. Then |ΔH| = 460 kJ ÷ 1 mol = 460 kJ/mol.
6. Complete combustion of 200 g of a fuel (molar mass M = 100 g/mol) releases 1080 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
540 kJ/mol
First find moles burned: n = 200 g ÷ 100 g/mol = 2 mol. Then |ΔH| = 1080 kJ ÷ 2 mol = 540 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1400 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
700 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 1400 kJ ÷ 2 mol = 700 kJ/mol.
8. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 100 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
500 kJ/mol
First find moles burned: n = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 100 kJ ÷ 0.2 mol = 500 kJ/mol.
9. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
760 kJ/mol
First find moles burned: n = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 380 kJ ÷ 0.5 mol = 760 kJ/mol.
10. Complete combustion of 40 g of a fuel (molar mass M = 40 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
300 kJ/mol
First find moles burned: n = 40 g ÷ 40 g/mol = 1 mol. Then |ΔH| = 300 kJ ÷ 1 mol = 300 kJ/mol.
11. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
160 kJ/mol
First find moles burned: n = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 80 kJ ÷ 0.5 mol = 160 kJ/mol.
12. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
640 kJ/mol
First find moles burned: n = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 2560 kJ ÷ 4 mol = 640 kJ/mol.

12 questions · Seed 47 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 16-18

Calorimetry & molar enthalpy change

Take your time. Show your thinking.

1. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 50 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 50 g (M = 100 g/mol) · Heat Q = 50 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 3200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 20 g/mol) · Heat Q = 3200 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 120 g of a fuel (molar mass M = 60 g/mol) releases 1520 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 120 g (M = 60 g/mol) · Heat Q = 1520 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 640 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 480 g (M = 120 g/mol) · Heat Q = 640 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 20 g of a fuel (molar mass M = 20 g/mol) releases 460 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 20 g (M = 20 g/mol) · Heat Q = 460 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 200 g of a fuel (molar mass M = 100 g/mol) releases 1080 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 200 g (M = 100 g/mol) · Heat Q = 1080 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1400 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 120 g/mol) · Heat Q = 1400 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 100 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 16 g (M = 80 g/mol) · Heat Q = 100 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 80 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 40 g of a fuel (molar mass M = 40 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 40 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 50 g (M = 100 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 20 g/mol) · Heat Q = 2560 kJ → |ΔH| = Q ÷ n

12 questions · Seed 47 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 16-18

Calorimetry & molar enthalpy change

Answers and reasoning. Review before teaching.

1. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 50 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
100 kJ/mol
First find moles burned: n = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 50 kJ ÷ 0.5 mol = 100 kJ/mol.
2. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 3200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
800 kJ/mol
First find moles burned: n = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 3200 kJ ÷ 4 mol = 800 kJ/mol.
3. Complete combustion of 120 g of a fuel (molar mass M = 60 g/mol) releases 1520 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
760 kJ/mol
First find moles burned: n = 120 g ÷ 60 g/mol = 2 mol. Then |ΔH| = 1520 kJ ÷ 2 mol = 760 kJ/mol.
4. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 640 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
160 kJ/mol
First find moles burned: n = 480 g ÷ 120 g/mol = 4 mol. Then |ΔH| = 640 kJ ÷ 4 mol = 160 kJ/mol.
5. Complete combustion of 20 g of a fuel (molar mass M = 20 g/mol) releases 460 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
460 kJ/mol
First find moles burned: n = 20 g ÷ 20 g/mol = 1 mol. Then |ΔH| = 460 kJ ÷ 1 mol = 460 kJ/mol.
6. Complete combustion of 200 g of a fuel (molar mass M = 100 g/mol) releases 1080 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
540 kJ/mol
First find moles burned: n = 200 g ÷ 100 g/mol = 2 mol. Then |ΔH| = 1080 kJ ÷ 2 mol = 540 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1400 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
700 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 1400 kJ ÷ 2 mol = 700 kJ/mol.
8. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 100 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
500 kJ/mol
First find moles burned: n = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 100 kJ ÷ 0.2 mol = 500 kJ/mol.
9. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
760 kJ/mol
First find moles burned: n = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 380 kJ ÷ 0.5 mol = 760 kJ/mol.
10. Complete combustion of 40 g of a fuel (molar mass M = 40 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
300 kJ/mol
First find moles burned: n = 40 g ÷ 40 g/mol = 1 mol. Then |ΔH| = 300 kJ ÷ 1 mol = 300 kJ/mol.
11. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
160 kJ/mol
First find moles burned: n = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 80 kJ ÷ 0.5 mol = 160 kJ/mol.
12. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
640 kJ/mol
First find moles burned: n = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 2560 kJ ÷ 4 mol = 640 kJ/mol.

12 questions · Seed 47 · Age guidance, not curriculum certification