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 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 310 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 108 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 = 108 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 20 g of a fuel (molar mass M = 100 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: 20 g (M = 100 g/mol) · Heat Q = 72 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2160 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 = 2160 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 50 g of a fuel (molar mass M = 100 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: 50 g (M = 100 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 40 g of a fuel (molar mass M = 80 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: 40 g (M = 80 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 360 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 = 360 kJ → |ΔH| = Q ÷ n
8. 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
9. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 160 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 = 160 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 960 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 = 960 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 20 g of a fuel (molar mass M = 100 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: 20 g (M = 100 g/mol) · Heat Q = 136 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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: 30 g (M = 60 g/mol) · Heat Q = 170 kJ → |ΔH| = Q ÷ n

12 questions · Seed 45 · 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 60 g of a fuel (molar mass M = 120 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 310 kJ ÷ 0.5 mol = 620 kJ/mol.
2. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 108 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 = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 108 kJ ÷ 0.2 mol = 540 kJ/mol.
3. Complete combustion of 20 g of a fuel (molar mass M = 100 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 = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 72 kJ ÷ 0.2 mol = 360 kJ/mol.
4. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2160 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 = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 2160 kJ ÷ 4 mol = 540 kJ/mol.
5. Complete combustion of 50 g of a fuel (molar mass M = 100 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
6. Complete combustion of 40 g of a fuel (molar mass M = 80 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 = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 360 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
180 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 360 kJ ÷ 2 mol = 180 kJ/mol.
8. 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.
9. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 160 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 160 kJ ÷ 0.5 mol = 320 kJ/mol.
10. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 960 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 960 kJ ÷ 4 mol = 240 kJ/mol.
11. Complete combustion of 20 g of a fuel (molar mass M = 100 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 = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 136 kJ ÷ 0.2 mol = 680 kJ/mol.
12. Complete combustion of 30 g of a fuel (molar mass M = 60 g/mol) releases 170 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 = 30 g ÷ 60 g/mol = 0.5 mol. Then |ΔH| = 170 kJ ÷ 0.5 mol = 340 kJ/mol.

12 questions · Seed 45 · 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 60 g of a fuel (molar mass M = 120 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: 60 g (M = 120 g/mol) · Heat Q = 310 kJ → |ΔH| = Q ÷ n
2. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 108 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 = 108 kJ → |ΔH| = Q ÷ n
3. Complete combustion of 20 g of a fuel (molar mass M = 100 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: 20 g (M = 100 g/mol) · Heat Q = 72 kJ → |ΔH| = Q ÷ n
4. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2160 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 = 2160 kJ → |ΔH| = Q ÷ n
5. Complete combustion of 50 g of a fuel (molar mass M = 100 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: 50 g (M = 100 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
6. Complete combustion of 40 g of a fuel (molar mass M = 80 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: 40 g (M = 80 g/mol) · Heat Q = 330 kJ → |ΔH| = Q ÷ n
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 360 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 = 360 kJ → |ΔH| = Q ÷ n
8. 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
9. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 160 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 = 160 kJ → |ΔH| = Q ÷ n
10. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 960 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 = 960 kJ → |ΔH| = Q ÷ n
11. Complete combustion of 20 g of a fuel (molar mass M = 100 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: 20 g (M = 100 g/mol) · Heat Q = 136 kJ → |ΔH| = Q ÷ n
12. Complete combustion of 30 g of a fuel (molar mass M = 60 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: 30 g (M = 60 g/mol) · Heat Q = 170 kJ → |ΔH| = Q ÷ n

12 questions · Seed 45 · 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 60 g of a fuel (molar mass M = 120 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 310 kJ ÷ 0.5 mol = 620 kJ/mol.
2. Complete combustion of 24 g of a fuel (molar mass M = 120 g/mol) releases 108 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 = 24 g ÷ 120 g/mol = 0.2 mol. Then |ΔH| = 108 kJ ÷ 0.2 mol = 540 kJ/mol.
3. Complete combustion of 20 g of a fuel (molar mass M = 100 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 = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 72 kJ ÷ 0.2 mol = 360 kJ/mol.
4. Complete combustion of 80 g of a fuel (molar mass M = 20 g/mol) releases 2160 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 = 80 g ÷ 20 g/mol = 4 mol. Then |ΔH| = 2160 kJ ÷ 4 mol = 540 kJ/mol.
5. Complete combustion of 50 g of a fuel (molar mass M = 100 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 = 50 g ÷ 100 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
6. Complete combustion of 40 g of a fuel (molar mass M = 80 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 = 40 g ÷ 80 g/mol = 0.5 mol. Then |ΔH| = 330 kJ ÷ 0.5 mol = 660 kJ/mol.
7. Complete combustion of 240 g of a fuel (molar mass M = 120 g/mol) releases 360 kJ of thermal energy in a calorimeter. Calculate the magnitude of the molar enthalpy of combustion |ΔH| in kJ/mol.
180 kJ/mol
First find moles burned: n = 240 g ÷ 120 g/mol = 2 mol. Then |ΔH| = 360 kJ ÷ 2 mol = 180 kJ/mol.
8. 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.
9. Complete combustion of 60 g of a fuel (molar mass M = 120 g/mol) releases 160 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 = 60 g ÷ 120 g/mol = 0.5 mol. Then |ΔH| = 160 kJ ÷ 0.5 mol = 320 kJ/mol.
10. Complete combustion of 240 g of a fuel (molar mass M = 60 g/mol) releases 960 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 = 240 g ÷ 60 g/mol = 4 mol. Then |ΔH| = 960 kJ ÷ 4 mol = 240 kJ/mol.
11. Complete combustion of 20 g of a fuel (molar mass M = 100 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 = 20 g ÷ 100 g/mol = 0.2 mol. Then |ΔH| = 136 kJ ÷ 0.2 mol = 680 kJ/mol.
12. Complete combustion of 30 g of a fuel (molar mass M = 60 g/mol) releases 170 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 = 30 g ÷ 60 g/mol = 0.5 mol. Then |ΔH| = 170 kJ ÷ 0.5 mol = 340 kJ/mol.

12 questions · Seed 45 · Age guidance, not curriculum certification