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 10 g of a fuel (molar mass M = 20 g/mol) releases 330 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 10 g (M = 20 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 20 g of a fuel (molar mass M = 20 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: 20 g (M = 20 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 4 g of a fuel (molar mass M = 20 g/mol) releases 72 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 4 g (M = 20 g/mol) · Heat Q = 72 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 120 g of a fuel (molar mass M = 120 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: 120 g (M = 120 g/mol) · Heat Q = 460 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 100 g of a fuel (molar mass M = 100 g/mol) releases 420 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 100 g (M = 100 g/mol) · Heat Q = 420 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 136 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 24 g (M = 120 g/mol) · Heat Q = 136 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1320 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 = 1320 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 75 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 10 g (M = 40 g/mol) · Heat Q = 75 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 195 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 15 g (M = 60 g/mol) · Heat Q = 195 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 88 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 = 88 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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: 30 g (M = 60 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n

12 questions · Seed 44 · 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 10 g of a fuel (molar mass M = 20 g/mol) releases 330 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
660 kJ/mol
First find moles burned: n = 10 g ÷ 20 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
2. Complete combustion of 20 g of a fuel (molar mass M = 20 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 = 20 g ÷ 20 g/mol = 1 mol. Then |ΔH| = 300 kJ ÷ 1 mol = 300 kJ/mol.
3. Complete combustion of 4 g of a fuel (molar mass M = 20 g/mol) releases 72 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
360 kJ/mol
First find moles burned: n = 4 g ÷ 20 g/mol = 0.2 mol. Then |ΔH| = 72 kJ ÷ 0.2 mol = 360 kJ/mol.
4. Complete combustion of 120 g of a fuel (molar mass M = 120 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 = 120 g ÷ 120 g/mol = 1 mol. Then |ΔH| = 460 kJ ÷ 1 mol = 460 kJ/mol.
5. Complete combustion of 100 g of a fuel (molar mass M = 100 g/mol) releases 420 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
420 kJ/mol
First find moles burned: n = 100 g ÷ 100 g/mol = 1 mol. Then |ΔH| = 420 kJ ÷ 1 mol = 420 kJ/mol.
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 136 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
680 kJ/mol
First find moles burned: n = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 136 kJ ÷ 0.2 mol = 680 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
660 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 1320 kJ ÷ 2 mol = 660 kJ/mol.
8. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
600 kJ/mol
First find moles burned: n = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 300 kJ ÷ 0.5 mol = 600 kJ/mol.
9. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 75 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 = 10 g ÷ 40 g/mol = 0.25 mol. Then |ΔH| = 75 kJ ÷ 0.25 mol = 300 kJ/mol.
10. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 195 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
780 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 195 kJ ÷ 0.25 mol = 780 kJ/mol.
11. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 88 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
440 kJ/mol
First find moles burned: n = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 88 kJ ÷ 0.2 mol = 440 kJ/mol.
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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 = 30 g ÷ 60 g/mol = 0.5 mol. Then |ΔH| = 80 kJ ÷ 0.5 mol = 160 kJ/mol.

12 questions · Seed 44 · 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 10 g of a fuel (molar mass M = 20 g/mol) releases 330 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 10 g (M = 20 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 20 g of a fuel (molar mass M = 20 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: 20 g (M = 20 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 4 g of a fuel (molar mass M = 20 g/mol) releases 72 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 4 g (M = 20 g/mol) · Heat Q = 72 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 120 g of a fuel (molar mass M = 120 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: 120 g (M = 120 g/mol) · Heat Q = 460 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 100 g of a fuel (molar mass M = 100 g/mol) releases 420 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 100 g (M = 100 g/mol) · Heat Q = 420 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 136 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 24 g (M = 120 g/mol) · Heat Q = 136 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1320 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 = 1320 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 300 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 75 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 10 g (M = 40 g/mol) · Heat Q = 75 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 195 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 15 g (M = 60 g/mol) · Heat Q = 195 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 88 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 = 88 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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: 30 g (M = 60 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n

12 questions · Seed 44 · 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 10 g of a fuel (molar mass M = 20 g/mol) releases 330 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
660 kJ/mol
First find moles burned: n = 10 g ÷ 20 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
2. Complete combustion of 20 g of a fuel (molar mass M = 20 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 = 20 g ÷ 20 g/mol = 1 mol. Then |ΔH| = 300 kJ ÷ 1 mol = 300 kJ/mol.
3. Complete combustion of 4 g of a fuel (molar mass M = 20 g/mol) releases 72 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
360 kJ/mol
First find moles burned: n = 4 g ÷ 20 g/mol = 0.2 mol. Then |ΔH| = 72 kJ ÷ 0.2 mol = 360 kJ/mol.
4. Complete combustion of 120 g of a fuel (molar mass M = 120 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 = 120 g ÷ 120 g/mol = 1 mol. Then |ΔH| = 460 kJ ÷ 1 mol = 460 kJ/mol.
5. Complete combustion of 100 g of a fuel (molar mass M = 100 g/mol) releases 420 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
420 kJ/mol
First find moles burned: n = 100 g ÷ 100 g/mol = 1 mol. Then |ΔH| = 420 kJ ÷ 1 mol = 420 kJ/mol.
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 136 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
680 kJ/mol
First find moles burned: n = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 136 kJ ÷ 0.2 mol = 680 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 1320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
660 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 1320 kJ ÷ 2 mol = 660 kJ/mol.
8. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 300 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
600 kJ/mol
First find moles burned: n = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 300 kJ ÷ 0.5 mol = 600 kJ/mol.
9. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 75 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 = 10 g ÷ 40 g/mol = 0.25 mol. Then |ΔH| = 75 kJ ÷ 0.25 mol = 300 kJ/mol.
10. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 195 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
780 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 195 kJ ÷ 0.25 mol = 780 kJ/mol.
11. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 88 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
440 kJ/mol
First find moles burned: n = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 88 kJ ÷ 0.2 mol = 440 kJ/mol.
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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 = 30 g ÷ 60 g/mol = 0.5 mol. Then |ΔH| = 80 kJ ÷ 0.5 mol = 160 kJ/mol.

12 questions · Seed 44 · Age guidance, not curriculum certification