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 240 g of a fuel (molar mass M = 60 g/mol) releases 2000 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 = 2000 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 8 g of a fuel (molar mass M = 40 g/mol) releases 96 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 = 96 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 160 g of a fuel (molar mass M = 80 g/mol) releases 600 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 160 g (M = 80 g/mol) · Heat Q = 600 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 60 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 = 60 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 60 g of a fuel (molar mass M = 60 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 = 60 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 120 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 = 120 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 135 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 = 135 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 50 g of a fuel (molar mass M = 100 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: 50 g (M = 100 g/mol) · Heat Q = 110 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 20 g of a fuel (molar mass M = 80 g/mol) releases 170 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 20 g (M = 80 g/mol) · Heat Q = 170 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 52 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 = 52 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 180 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 = 180 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 310 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 = 310 kJ → |ΔH| = Q ÷ n

12 questions · Seed 42 · 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 240 g of a fuel (molar mass M = 60 g/mol) releases 2000 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 2000 kJ ÷ 4 mol = 500 kJ/mol.
2. Complete combustion of 8 g of a fuel (molar mass M = 40 g/mol) releases 96 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
480 kJ/mol
First find moles burned: n = 8 g ÷ 40 g/mol = 0.2 mol. Then |ΔH| = 96 kJ ÷ 0.2 mol = 480 kJ/mol.
3. Complete combustion of 160 g of a fuel (molar mass M = 80 g/mol) releases 600 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 = 160 g ÷ 80 g/mol = 2 mol. Then |ΔH| = 600 kJ ÷ 2 mol = 300 kJ/mol.
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 60 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 = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 60 kJ ÷ 0.25 mol = 240 kJ/mol.
5. Complete combustion of 60 g of a fuel (molar mass M = 60 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
380 kJ/mol
First find moles burned: n = 60 g ÷ 60 g/mol = 1 mol. Then |ΔH| = 380 kJ ÷ 1 mol = 380 kJ/mol.
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 120 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 = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 120 kJ ÷ 0.2 mol = 600 kJ/mol.
7. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 135 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 = 25 g ÷ 100 g/mol = 0.25 mol. Then |ΔH| = 135 kJ ÷ 0.25 mol = 540 kJ/mol.
8. Complete combustion of 50 g of a fuel (molar mass M = 100 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 110 kJ ÷ 0.5 mol = 220 kJ/mol.
9. Complete combustion of 20 g of a fuel (molar mass M = 80 g/mol) releases 170 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 = 20 g ÷ 80 g/mol = 0.25 mol. Then |ΔH| = 170 kJ ÷ 0.25 mol = 680 kJ/mol.
10. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 52 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 = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 52 kJ ÷ 0.2 mol = 260 kJ/mol.
11. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 180 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
720 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 180 kJ ÷ 0.25 mol = 720 kJ/mol.
12. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 310 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
620 kJ/mol
First find moles burned: n = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 310 kJ ÷ 0.5 mol = 620 kJ/mol.

12 questions · Seed 42 · 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 240 g of a fuel (molar mass M = 60 g/mol) releases 2000 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 = 2000 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 8 g of a fuel (molar mass M = 40 g/mol) releases 96 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 = 96 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 160 g of a fuel (molar mass M = 80 g/mol) releases 600 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 160 g (M = 80 g/mol) · Heat Q = 600 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 60 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 = 60 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 60 g of a fuel (molar mass M = 60 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 = 60 g/mol) · Heat Q = 380 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 120 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 = 120 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 135 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 = 135 kJ → |ΔH| = Q ÷ n
8. Complete combustion of 50 g of a fuel (molar mass M = 100 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: 50 g (M = 100 g/mol) · Heat Q = 110 kJ → |ΔH| = Q ÷ n
9. Complete combustion of 20 g of a fuel (molar mass M = 80 g/mol) releases 170 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
Fuel: 20 g (M = 80 g/mol) · Heat Q = 170 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 52 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 = 52 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 180 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 = 180 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 310 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 = 310 kJ → |ΔH| = Q ÷ n

12 questions · Seed 42 · 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 240 g of a fuel (molar mass M = 60 g/mol) releases 2000 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 2000 kJ ÷ 4 mol = 500 kJ/mol.
2. Complete combustion of 8 g of a fuel (molar mass M = 40 g/mol) releases 96 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
480 kJ/mol
First find moles burned: n = 8 g ÷ 40 g/mol = 0.2 mol. Then |ΔH| = 96 kJ ÷ 0.2 mol = 480 kJ/mol.
3. Complete combustion of 160 g of a fuel (molar mass M = 80 g/mol) releases 600 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 = 160 g ÷ 80 g/mol = 2 mol. Then |ΔH| = 600 kJ ÷ 2 mol = 300 kJ/mol.
4. Complete combustion of 5 g of a fuel (molar mass M = 20 g/mol) releases 60 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 = 5 g ÷ 20 g/mol = 0.25 mol. Then |ΔH| = 60 kJ ÷ 0.25 mol = 240 kJ/mol.
5. Complete combustion of 60 g of a fuel (molar mass M = 60 g/mol) releases 380 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
380 kJ/mol
First find moles burned: n = 60 g ÷ 60 g/mol = 1 mol. Then |ΔH| = 380 kJ ÷ 1 mol = 380 kJ/mol.
6. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 120 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 = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 120 kJ ÷ 0.2 mol = 600 kJ/mol.
7. Complete combustion of 25 g of a fuel (molar mass M = 100 g/mol) releases 135 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 = 25 g ÷ 100 g/mol = 0.25 mol. Then |ΔH| = 135 kJ ÷ 0.25 mol = 540 kJ/mol.
8. Complete combustion of 50 g of a fuel (molar mass M = 100 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 110 kJ ÷ 0.5 mol = 220 kJ/mol.
9. Complete combustion of 20 g of a fuel (molar mass M = 80 g/mol) releases 170 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 = 20 g ÷ 80 g/mol = 0.25 mol. Then |ΔH| = 170 kJ ÷ 0.25 mol = 680 kJ/mol.
10. Complete combustion of 16 g of a fuel (molar mass M = 80 g/mol) releases 52 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 = 16 g ÷ 80 g/mol = 0.2 mol. Then |ΔH| = 52 kJ ÷ 0.2 mol = 260 kJ/mol.
11. Complete combustion of 15 g of a fuel (molar mass M = 60 g/mol) releases 180 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
720 kJ/mol
First find moles burned: n = 15 g ÷ 60 g/mol = 0.25 mol. Then |ΔH| = 180 kJ ÷ 0.25 mol = 720 kJ/mol.
12. Complete combustion of 40 g of a fuel (molar mass M = 80 g/mol) releases 310 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
620 kJ/mol
First find moles burned: n = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 310 kJ ÷ 0.5 mol = 620 kJ/mol.

12 questions · Seed 42 · Age guidance, not curriculum certification