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 40 g of a fuel (molar mass M = 80 g/mol) releases 350 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 = 350 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 20 g of a fuel (molar mass M = 40 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: 20 g (M = 40 g/mol) · Heat Q = 50 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 1760 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 = 1760 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 5 g of a fuel (molar mass M = 20 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: 5 g (M = 20 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 320 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 = 320 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 85 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 = 85 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 60 g/mol) · Heat Q = 1200 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 70 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 5 g (M = 20 g/mol) · Heat Q = 70 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 5 g of a fuel (molar mass M = 20 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: 5 g (M = 20 g/mol) · Heat Q = 75 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 160 g of a fuel (molar mass M = 40 g/mol) releases 3120 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 160 g (M = 40 g/mol) · Heat Q = 3120 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 120 g of a fuel (molar mass M = 120 g/mol) releases 740 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 = 740 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 2320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 60 g/mol) · Heat Q = 2320 kJ → |ΔH| = Q ÷ n

12 questions · Seed 48 · 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 40 g of a fuel (molar mass M = 80 g/mol) releases 350 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 = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 350 kJ ÷ 0.5 mol = 700 kJ/mol.
2. Complete combustion of 20 g of a fuel (molar mass M = 40 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 = 20 g ÷ 40 g/mol = 0.5 mol. Then |ΔH| = 50 kJ ÷ 0.5 mol = 100 kJ/mol.
3. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 1760 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 = 480 g ÷ 120 g/mol = 4 mol. Then |ΔH| = 1760 kJ ÷ 4 mol = 440 kJ/mol.
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
320 kJ/mol
First find moles burned: n = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 80 kJ ÷ 0.25 mol = 320 kJ/mol.
5. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 320 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 320 kJ ÷ 0.5 mol = 640 kJ/mol.
6. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 85 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
340 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 85 kJ ÷ 0.25 mol = 340 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1200 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 1200 kJ ÷ 4 mol = 300 kJ/mol.
8. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 70 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
280 kJ/mol
First find moles burned: n = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 70 kJ ÷ 0.25 mol = 280 kJ/mol.
9. Complete combustion of 5 g of a fuel (molar mass M = 20 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 = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 75 kJ ÷ 0.25 mol = 300 kJ/mol.
10. Complete combustion of 160 g of a fuel (molar mass M = 40 g/mol) releases 3120 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 = 160 g ÷ 40 g/mol = 4 mol. Then |ΔH| = 3120 kJ ÷ 4 mol = 780 kJ/mol.
11. Complete combustion of 120 g of a fuel (molar mass M = 120 g/mol) releases 740 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
740 kJ/mol
First find moles burned: n = 120 g ÷ 120 g/mol = 1 mol. Then |ΔH| = 740 kJ ÷ 1 mol = 740 kJ/mol.
12. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 2320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
580 kJ/mol
First find moles burned: n = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 2320 kJ ÷ 4 mol = 580 kJ/mol.

12 questions · Seed 48 · 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 40 g of a fuel (molar mass M = 80 g/mol) releases 350 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 = 350 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 20 g of a fuel (molar mass M = 40 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: 20 g (M = 40 g/mol) · Heat Q = 50 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 1760 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 = 1760 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 5 g of a fuel (molar mass M = 20 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: 5 g (M = 20 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 320 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 = 320 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 85 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 = 85 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1200 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 60 g/mol) · Heat Q = 1200 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 70 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 5 g (M = 20 g/mol) · Heat Q = 70 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 5 g of a fuel (molar mass M = 20 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: 5 g (M = 20 g/mol) · Heat Q = 75 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 160 g of a fuel (molar mass M = 40 g/mol) releases 3120 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 160 g (M = 40 g/mol) · Heat Q = 3120 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 120 g of a fuel (molar mass M = 120 g/mol) releases 740 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 = 740 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 2320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 240 g (M = 60 g/mol) · Heat Q = 2320 kJ → |ΔH| = Q ÷ n

12 questions · Seed 48 · 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 40 g of a fuel (molar mass M = 80 g/mol) releases 350 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 = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 350 kJ ÷ 0.5 mol = 700 kJ/mol.
2. Complete combustion of 20 g of a fuel (molar mass M = 40 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 = 20 g ÷ 40 g/mol = 0.5 mol. Then |ΔH| = 50 kJ ÷ 0.5 mol = 100 kJ/mol.
3. Complete combustion of 480 g of a fuel (molar mass M = 120 g/mol) releases 1760 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 = 480 g ÷ 120 g/mol = 4 mol. Then |ΔH| = 1760 kJ ÷ 4 mol = 440 kJ/mol.
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 80 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
320 kJ/mol
First find moles burned: n = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 80 kJ ÷ 0.25 mol = 320 kJ/mol.
5. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 320 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 320 kJ ÷ 0.5 mol = 640 kJ/mol.
6. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 85 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
340 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 85 kJ ÷ 0.25 mol = 340 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1200 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 1200 kJ ÷ 4 mol = 300 kJ/mol.
8. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 70 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
280 kJ/mol
First find moles burned: n = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 70 kJ ÷ 0.25 mol = 280 kJ/mol.
9. Complete combustion of 5 g of a fuel (molar mass M = 20 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 = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 75 kJ ÷ 0.25 mol = 300 kJ/mol.
10. Complete combustion of 160 g of a fuel (molar mass M = 40 g/mol) releases 3120 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 = 160 g ÷ 40 g/mol = 4 mol. Then |ΔH| = 3120 kJ ÷ 4 mol = 780 kJ/mol.
11. Complete combustion of 120 g of a fuel (molar mass M = 120 g/mol) releases 740 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
740 kJ/mol
First find moles burned: n = 120 g ÷ 120 g/mol = 1 mol. Then |ΔH| = 740 kJ ÷ 1 mol = 740 kJ/mol.
12. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 2320 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
580 kJ/mol
First find moles burned: n = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 2320 kJ ÷ 4 mol = 580 kJ/mol.

12 questions · Seed 48 · Age guidance, not curriculum certification