R1.3 Energy from fuels questions for IB Chemistry

106 questions on Energy from fuels, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

IB Chemistry
Part of R1 What drives chemical reactions?
SL and HL

Questions by paper and level

SL and HL questions are for students at either level. HL only questions cover what only HL students study.

Paper	SL and HL	HL only	All
Paper 1A	33	5	38
Paper 1B	11	4	15
Paper 2	37	16	53
Every paper	81	25	106

Counted on 10 November 2026

Questions to try

Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · CHEM-00302Paper 1A · 1 mark

Butane, C₄H₁₀, is used as a fuel in portable gas stoves. What is the coefficient of oxygen when the equation for the complete combustion of one mole of butane is balanced?

A
4
B
5
C
$6 \frac{1}{2}$
D
13

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Question 2 · CHEM-01120Paper 1B · HL only · 11 marks

A student used a spirit burner to heat 150.0 g of water in a copper can, in order to determine the enthalpy of combustion of ethanol and then use it to find the enthalpy of formation of ethanol.

Measurement	Value
Mass of burner and ethanol before / g ± 0.001 g	45.672
Mass of burner and ethanol after / g ± 0.001 g	45.012
Initial temperature of water / °C ± 0.1 °C	19.8
Final temperature of water / °C ± 0.1 °C	40.5

(a)
Determine the enthalpy of combustion of ethanol, in kJ mol⁻¹, from these results.
3 marks
(b)
Calculate the percentage uncertainty in the value of $Δ H_{c}$ , considering only the mass of ethanol burned and the temperature change.
2 marks
(c)
Calculate the percentage error in the value of $Δ H_{c}$ using section 14 of the data booklet.
1 mark
(d)
Using your answers to (b) and (c), evaluate whether the difference from the literature value is due mainly to random or to systematic errors, and identify one systematic error.
2 marks
(e)
Use the student's value of $Δ H_{c}$ to determine the standard enthalpy change of formation of ethanol, in kJ mol⁻¹, and compare it with the value in section 13 of the data booklet.
2 marks
(f)
Suggest why a small percentage error in $Δ H_{c}$ would lead to a much larger percentage error in $Δ H_{f}$ calculated in this way.
1 mark

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Question 3 · CHEM-00557Paper 2 · 7 marks

The standard enthalpies of combustion of four primary alcohols are shown.

Alcohol	Formula	$Δ H_{c}^{\circ}$ / kJ mol⁻¹
methanol	$C H_{3} O H$	−726
ethanol	$C_{2} H_{5} O H$	−1367
propan-1-ol	$C_{3} H_{7} O H$	−2021
butan-1-ol	$C_{4} H_{9} O H$	−2676

(a)
Calculate the mean difference in $Δ H_{c}^{\circ}$ between successive members of the series.
1 mark
(b)
Explain why $Δ H_{c}^{\circ}$ becomes more negative by an approximately constant amount from one member to the next.
2 marks
(c)
Predict $Δ H_{c}^{\circ}$ for pentan-1-ol.
1 mark
(d)
Write the equation for the complete combustion of propan-1-ol.
1 mark
(e)
Determine the energy released per gram, in kJ g⁻¹, for ethanol and for butan-1-ol, and state which is the better fuel on this basis.
2 marks

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Question 4 · CHEM-00303Paper 1A · 1 mark

Which equation represents the complete combustion of propan-1-ol?

A
$C_{3} H_{7} O H (l) + 4 O_{2} (g) \to 3 C O_{2} (g) + 4 H_{2} O (l)$
B
$C_{3} H_{7} O H (l) + 4 \frac{1}{2} O_{2} (g) \to 3 C O_{2} (g) + 4 H_{2} O (l)$
C
$C_{3} H_{7} O H (l) + 5 O_{2} (g) \to 3 C O_{2} (g) + 4 H_{2} O (l)$
D
$C_{3} H_{7} O H (l) + 3 O_{2} (g) \to 3 C O (g) + 4 H_{2} O (l)$

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Question 5 · CHEM-01122Paper 1B · HL only · 10 marks

A butane gas lighter was used to heat 100.0 g of water in a metal can. The flame was yellow and a layer of soot formed on the bottom of the can.

Measurement	Value
Mass of lighter before / g ± 0.001 g	52.418
Mass of lighter after / g ± 0.001 g	52.168
Initial temperature of water / °C ± 0.1 °C	19.6
Final temperature of water / °C ± 0.1 °C	37.4

(a)
Calculate the enthalpy of combustion of butane, in kJ mol⁻¹, from these results.
2 marks
(b)
Calculate the standard enthalpy change of combustion of butane, in kJ mol⁻¹, using section 13 of the data booklet.
2 marks
(c)
Calculate the percentage error in the experimental value, using the section 14 value of −2878 kJ mol⁻¹.
1 mark
(d)
Calculate the standard enthalpy change, in kJ mol⁻¹, for the incomplete combustion of butane to carbon monoxide and liquid water, using section 13 of the data booklet.
2 marks
(e)
Evaluate whether incomplete combustion alone can explain the experimental result.
2 marks
(f)
Suggest why the lighter should be dried and allowed to warm to room temperature before it is reweighed.
1 mark

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Question 6 · CHEM-00796Paper 2 · 7 marks

Propane, $C_{3} H_{8}$ , is the main component of liquefied petroleum gas (LPG). In the gas phase, its complete combustion can be represented as:

C_{3} H_{8} (g) + 5 O_{2} (g) \to 3 C O_{2} (g) + 4 H_{2} O (g)

(a)
Deduce the number of C–H and C–C bonds in one molecule of propane.
1 mark
(b)
Calculate the enthalpy change, in kJ mol⁻¹, for this reaction. Use section 12 of the data booklet.
3 marks
(c)
The standard enthalpy of combustion of propane is −2219 kJ mol⁻¹. Explain why this value differs from your answer to (b).
2 marks
(d)
Using your answer to (b), state whether the products or the reactants are more stable.
1 mark

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