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 = 20 g/mol) releases 480 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 20 g/mol) · Heat Q = 480 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 12 g of a fuel (molar mass M = 60 g/mol) releases 92 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 12 g (M = 60 g/mol) · Heat Q = 92 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 40 g/mol) · Heat Q = 1560 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 10 g of a fuel (molar mass M = 20 g/mol) releases 110 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 = 110 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 40 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 = 40 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1040 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 40 g/mol) · Heat Q = 1040 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 370 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 = 370 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1440 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 = 1440 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 65 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 25 g (M = 100 g/mol) · Heat Q = 65 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 20 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: 20 g (M = 100 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 8 g of a fuel (molar mass M = 40 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: 8 g (M = 40 g/mol) · Heat Q = 88 kJ → |ΔH| = Q ÷ n

12 questions · Seed 104730 · 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 = 20 g/mol) releases 480 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
240 kJ/mol
First find moles burned: n = 40 g ÷ 20 g/mol = 2 mol. Then |ΔH| = 480 kJ ÷ 2 mol = 240 kJ/mol.
2. Complete combustion of 12 g of a fuel (molar mass M = 60 g/mol) releases 92 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 = 12 g ÷ 60 g/mol = 0.2 mol. Then |ΔH| = 92 kJ ÷ 0.2 mol = 460 kJ/mol.
3. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1560 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 = 80 g ÷ 40 g/mol = 2 mol. Then |ΔH| = 1560 kJ ÷ 2 mol = 780 kJ/mol.
4. Complete combustion of 10 g of a fuel (molar mass M = 20 g/mol) releases 110 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
220 kJ/mol
First find moles burned: n = 10 g ÷ 20 g/mol = 0.5 mol. Then |ΔH| = 110 kJ ÷ 0.5 mol = 220 kJ/mol.
5. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 40 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 = 10 g ÷ 40 g/mol = 0.25 mol. Then |ΔH| = 40 kJ ÷ 0.25 mol = 160 kJ/mol.
6. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1040 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
520 kJ/mol
First find moles burned: n = 80 g ÷ 40 g/mol = 2 mol. Then |ΔH| = 1040 kJ ÷ 2 mol = 520 kJ/mol.
7. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 370 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 370 kJ ÷ 0.5 mol = 740 kJ/mol.
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 380 kJ ÷ 0.5 mol = 760 kJ/mol.
9. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1440 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 1440 kJ ÷ 4 mol = 360 kJ/mol.
10. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 65 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
260 kJ/mol
First find moles burned: n = 25 g ÷ 100 g/mol = 0.25 mol. Then |ΔH| = 65 kJ ÷ 0.25 mol = 260 kJ/mol.
11. Complete combustion of 20 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.
400 kJ/mol
First find moles burned: n = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 80 kJ ÷ 0.2 mol = 400 kJ/mol.
12. Complete combustion of 8 g of a fuel (molar mass M = 40 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 = 8 g ÷ 40 g/mol = 0.2 mol. Then |ΔH| = 88 kJ ÷ 0.2 mol = 440 kJ/mol.

12 questions · Seed 104730 · 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 = 20 g/mol) releases 480 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 40 g (M = 20 g/mol) · Heat Q = 480 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 12 g of a fuel (molar mass M = 60 g/mol) releases 92 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 12 g (M = 60 g/mol) · Heat Q = 92 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1560 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 40 g/mol) · Heat Q = 1560 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 10 g of a fuel (molar mass M = 20 g/mol) releases 110 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 = 110 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 40 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 = 40 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1040 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 80 g (M = 40 g/mol) · Heat Q = 1040 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 370 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 = 370 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1440 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 = 1440 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 65 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 25 g (M = 100 g/mol) · Heat Q = 65 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 20 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: 20 g (M = 100 g/mol) · Heat Q = 80 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 8 g of a fuel (molar mass M = 40 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: 8 g (M = 40 g/mol) · Heat Q = 88 kJ → |ΔH| = Q ÷ n

12 questions · Seed 104730 · 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 = 20 g/mol) releases 480 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
240 kJ/mol
First find moles burned: n = 40 g ÷ 20 g/mol = 2 mol. Then |ΔH| = 480 kJ ÷ 2 mol = 240 kJ/mol.
2. Complete combustion of 12 g of a fuel (molar mass M = 60 g/mol) releases 92 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 = 12 g ÷ 60 g/mol = 0.2 mol. Then |ΔH| = 92 kJ ÷ 0.2 mol = 460 kJ/mol.
3. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1560 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 = 80 g ÷ 40 g/mol = 2 mol. Then |ΔH| = 1560 kJ ÷ 2 mol = 780 kJ/mol.
4. Complete combustion of 10 g of a fuel (molar mass M = 20 g/mol) releases 110 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
220 kJ/mol
First find moles burned: n = 10 g ÷ 20 g/mol = 0.5 mol. Then |ΔH| = 110 kJ ÷ 0.5 mol = 220 kJ/mol.
5. Complete combustion of 10 g of a fuel (molar mass M = 40 g/mol) releases 40 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 = 10 g ÷ 40 g/mol = 0.25 mol. Then |ΔH| = 40 kJ ÷ 0.25 mol = 160 kJ/mol.
6. Complete combustion of 80 g of a fuel (molar mass M = 40 g/mol) releases 1040 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
520 kJ/mol
First find moles burned: n = 80 g ÷ 40 g/mol = 2 mol. Then |ΔH| = 1040 kJ ÷ 2 mol = 520 kJ/mol.
7. Complete combustion of 50 g of a fuel (molar mass M = 100 g/mol) releases 370 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 370 kJ ÷ 0.5 mol = 740 kJ/mol.
8. Complete combustion of 60 g of a fuel (molar mass M = 120 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 380 kJ ÷ 0.5 mol = 760 kJ/mol.
9. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 1440 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 1440 kJ ÷ 4 mol = 360 kJ/mol.
10. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 65 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
260 kJ/mol
First find moles burned: n = 25 g ÷ 100 g/mol = 0.25 mol. Then |ΔH| = 65 kJ ÷ 0.25 mol = 260 kJ/mol.
11. Complete combustion of 20 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.
400 kJ/mol
First find moles burned: n = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 80 kJ ÷ 0.2 mol = 400 kJ/mol.
12. Complete combustion of 8 g of a fuel (molar mass M = 40 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 = 8 g ÷ 40 g/mol = 0.2 mol. Then |ΔH| = 88 kJ ÷ 0.2 mol = 440 kJ/mol.

12 questions · Seed 104730 · Age guidance, not curriculum certification