1. Which types of reaction are always exothermic?

I. Neutralization

II. Decomposition

III. Combustion

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

2. Which processes have a negative enthalpy change?

I. 2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(l)

II. HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

III. H2O(g) → H2O(l)

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

IB Questionbank Chemistry 1
3. Which of the following reactions are exothermic?

I. CH4 + 2O2 → CO2 + 2H2O

II. NaOH + HCl → NaCl + H2O

III. Br2 → 2Br

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

4. When some solid barium hydroxide and solid ammonium thiosulfate were reacted together, the
temperature of the surroundings was observed to decrease from 15 ºC to – 4 ºC. What can be
deduced from this observation?

A. The reaction is exothermic and ∆H is negative.

B. The reaction is exothermic and ∆H is positive.

C. The reaction is endothermic and ∆H is negative.

D. The reaction is endothermic and ∆H is positive.

(Total 1 mark)

IB Questionbank Chemistry 2
5. Which statement is correct given the enthalpy level diagram below?

A. The reaction is endothermic and the products are more thermodynamically stable than the
reactants.

B. The reaction is exothermic and the products are more thermodynamically stable than the
reactants.

C. The reaction is endothermic and the reactants are more thermodynamically stable than the
products.

D. The reaction is exothermic and the reactants are more thermodynamically stable than the
products.
(Total 1 mark)

6. Which is true for a chemical reaction in which the products have a higher enthalpy than the
reactants?

Reaction ∆H
A. endothermic positive
B. endothermic negative
C. exothermic positive
D. exothermic negative
(Total 1 mark)

IB Questionbank Chemistry 3
7. What is the energy, in kJ, released when 1.00 mol of carbon monoxide is burned according to
the following equation?

2CO(g) + O2(g) → 2CO2(g) ΔHo = –564 kJ

A. 141

B. 282

C. 564

D. 1128
(Total 1 mark)

8. Which statement about bonding is correct?

A. Bond breaking is endothermic and requires energy.

B. Bond breaking is endothermic and releases energy.

C. Bond making is exothermic and requires energy.

D. Bond making is endothermic and releases energy.

(Total 1 mark)

9. In a reaction that occurs in 50 g of aqueous solution, the temperature of the reaction mixture
increases by 20 °C. If 0.10 mol of the limiting reagent is consumed, what is the enthalpy change
(in kJ mol–1) for the reaction? Assume the specific heat capacity of the solution
= 4.2 kJ kg–1 K–1.

A. –0.10 × 50 × 4.2 × 20

B. –0.10 × 0.050 × 4.2 × 20

− 50  4.2  20
C.
0.10

− 0.050 4.2  20
D.
0.10
(Total 1 mark)

IB Questionbank Chemistry 4
10. 1.0 g of sodium hydroxide, NaOH, was added to 99.0 g of water. The temperature of the
solution increased from 18.0 ºC to 20.5 ºC. The specific heat capacity of the solution is
4.18 J g–1 K–1.
Which expression gives the heat evolved in kJ mol–1?

2.5 100.0  4.18 1000

A.
40.0

2.5 100.0  4.18

B.
1000 40.0

2.5 100.0  4.18  40.0

C.
1000

2.5 1.0  4.18  40.0

D.
1000
(Total 1 mark)

11. How much energy, in joules, is required to increase the temperature of 2.0 g of aluminium from
25 to 30 °C? (Specific heat of Al = 0.90 J g–1 K–1).

A. 0.36

B. 4.5

C. 9.0

D. 54
(Total 1 mark)

IB Questionbank Chemistry 5
12. A pure aluminium block with a mass of 10 g is heated so that its temperature increases from
20 °C to 50 °C . The specific heat capacity of aluminium is 8.99 × 10–1 J g–1 K–1. Which
expression gives the heat energy change in kJ?

A. 10 × 8.99 × 10–1 × 303

B. 10 × 8.99 × 10–1 × 30

10  8.99 10 −1  303

C.
1000

10  8.99  10 −1  30
D.
1000
(Total 1 mark)

13. Identical pieces of magnesium are added to two beakers, A and B, containing hydrochloric acid.
Both acids have the same initial temperature but their volumes and concentrations differ.

Which statement is correct?

A. The maximum temperature in A will be higher than in B.

B. The maximum temperature in A and B will be equal.

C. It is not possible to predict whether A or B will have the higher maximum temperature.

D. The temperature in A and B will increase at the same rate.

(Total 1 mark)

IB Questionbank Chemistry 6
14. When 100 cm3 of 1.0 mol dm–3 HCl is mixed with 100 cm3 of 1.0 mol dm–3 NaOH, the
temperature of the resulting solution increases by 5.0 °C. What will be the temperature change,
in °C, when 50 cm3 of these two solutions are mixed?

A. 2.5

B. 5.0

C. 10

D. 20
(Total 1 mark)

15. Some water is heated using the heat produced by the combustion of magnesium metal. Which
values are needed to calculate the enthalpy change of reaction?

I. The mass of magnesium

II. The mass of the water

III. The change in temperature of the water

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
(Total 1 mark)

IB Questionbank Chemistry 7
16. Consider the following reactions.

1
Cu2O(s) + O2(g) → 2CuO(s) ∆HO = –144 kJ
2
Cu2O(s) → Cu(s) + CuO(s) ∆HO = +11 kJ

What is the value of ∆HO, in kJ, for this reaction?

1
Cu(s) + O2(g) → CuO(s)
2

A. –144 + 11

B. +144 – 11

C. –144 – 11

D. +144 + 11
(Total 1 mark)

17. Consider the two reactions involving iron and oxygen.

2Fe(s) + O2(g) → 2FeO(s) ∆HO = –544 kJ

4Fe(s) + 3O2(g) → 2Fe2O3(s) ∆HO = –1648 kJ

What is the enthalpy change, in kJ, for the reaction below?

4FeO(s) + O2(g) → 2Fe2O3(s)

A. –1648 – 2(–544)

B. –544 – (–1648)

C. –1648 – 544

D. –1648 – 2(544)
(Total 1 mark)

IB Questionbank Chemistry 8
18. Consider the following reactions.

N2(g) + O2(g) → 2NO(g) ∆HO = +180 kJ

2NO2(g) → 2NO(g) + O2(g) ∆HO = +112 kJ

What is the ∆HO value, in kJ, for the following reaction?

N2(g) + 2O2(g) → 2NO2(g)

A. –1 × (+180) + –1 × (+112)

B. –1 × (+180) + 1 × (+112)

C. 1 × (+180) + –1 × (+112)

D. 1 × (+180) + 1 × (+112)
(Total 1 mark)

19. The standard enthalpy changes for the combustion of carbon and carbon monoxide are shown
below.

C(s) + O2(g) → CO2(g) ∆HcO = –394 kJmol–1

1
CO(g) + O2(g) → CO2(g) ΔHcO = –283 kJ mol–1
2

What is the standard enthalpy change, in kJ, for the following reaction?

1
C(s) + O2(g) → CO(g)
2

A. –677

B. –111

C. +111

D. +677
(Total 1 mark)

IB Questionbank Chemistry 9
20. Using the equations below:

C(s) + O2(g) → CO2(g) ∆Hο = –394 kJ mol–1

Mn(s) + O2(g) → MnO2(s) ∆Hο = –520 kJ mol–1

What is ∆H, in kJ, for the following reaction?

MnO2(s) + C(s) → Mn(s) + CO2(g)

A. 914

B. 126

C. –126

D. –914
(Total 1 mark)

21. Which equation represents the bond enthalpy for the H–Br bond in hydrogen bromide?

A. HBr(g) → H(g) + Br(g)

B. HBr(g) → H(g) + Br(l)

1
C. HBr(g) → H(g) + Br2(1)
2

1
D. HBr(g) → H(g) + Br2(g)
2
(Total 1 mark)

22. Which process represents the C–Cl bond enthalpy in tetrachloromethane?

A. CCl4(g) → C(g) + 4Cl(g)

B. CCl4(g) → CCl3(g) + Cl(g)

C. CCl4(l) → C(g) + 4Cl(g)

D. CCl4(l) → C(s) + 2Cl2(g)

(Total 1 mark)

IB Questionbank Chemistry 10
23. Use the average bond enthalpies below to calculate the enthalpy change, in kJ, for the following
reaction.

H2(g) + I2(g) → 2HI(g)

Bond Bond energy / kJ mol–1

H–H 440
I–I 150
H–I 300

A. +290

B. +10

C. –10

D. –290
(Total 1 mark)

24. Methanol is made in large quantities as it is used in the production of polymers and in fuels.
The enthalpy of combustion of methanol can be determined theoretically or experimentally.

1
CH3OH(l) + 1 O2(g) → CO2(g) + 2H2O(g)
2

(a) Using the information from Table 10 of the Data Booklet, determine the theoretical
enthalpy of combustion of methanol.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

IB Questionbank Chemistry 11
 (b) The enthalpy of combustion of methanol can also be determined experimentally in a
school laboratory. A burner containing methanol was weighed and used to heat water in a
test tube as illustrated below.

The following data were collected.

Initial mass of burner and methanol / g 80.557

Final mass of burner and methanol / g 80.034
Mass of water in test tube / g 20.000
Initial temperature of water / °C 21.5
Final temperature of water / °C 26.4

(i) Calculate the amount, in mol, of methanol burned.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Chemistry 12
 (ii) Calculate the heat absorbed, in kJ, by the water.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(iii) Determine the enthalpy change, in kJ mol–1, for the combustion of 1 mole of
methanol.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(c) The Data Booklet value for the enthalpy of combustion of methanol is –726 kJ mol–1.
Suggest why this value differs from the values calculated in parts (a) and (b).

(i) Part (a)

...........................................................................................................................

...........................................................................................................................
(1)

(ii) Part (b)

...........................................................................................................................

...........................................................................................................................
(1)
(Total 12 marks)

IB Questionbank Chemistry 13
25. One important property of a rocket fuel mixture is the large volume of gaseous products formed
which provide thrust. Hydrazine, N2H4, is often used as a rocket fuel. The combustion of
hydrazine is represented by the equation below.

N2H4(g) + O2(g) → N2(g) + 2H2O(g) ∆HcO = –585 kJ mol–1

(a) Hydrazine reacts with fluorine to produce nitrogen and hydrogen fluoride, all in the
gaseous state. State an equation for the reaction.

......................................................................................................................................

......................................................................................................................................
(2)

(b) Draw the Lewis structures for hydrazine and nitrogen.

(2)

(c) Use the average bond enthalpies given in Table 10 of the Data Booklet to determine the
enthalpy change for the reaction in part (a) above.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

IB Questionbank Chemistry 14
 (d) Based on your answers to parts (a) and (c), suggest whether a mixture of hydrazine and
fluorine is a better rocket fuel than a mixture of hydrazine and oxygen.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)
(Total 9 marks)

26. Two students were asked to use information from the Data Booklet to calculate a value for the
enthalpy of hydrogenation of ethene to form ethane.

C2H4(g) + H2(g) → C2H6(g)

John used the average bond enthalpies from Table 10. Marit used the values of enthalpies of
combustion from Table 12.

(a) Calculate the value for the enthalpy of hydrogenation of ethene obtained using the
average bond enthalpies given in Table 10.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Chemistry 15
 (b) Marit arranged the values she found in Table 12 into an energy cycle.

Calculate the value for the enthalpy of hydrogenation of ethene from the energy cycle.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(1)

(c) Suggest one reason why John’s answer is slightly less accurate than Marit’s answer.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(1)

(d) John then decided to determine the enthalpy of hydrogenation of cyclohexene to produce
cyclohexane.

C6H10(l) + H2(g) → C6H12(l)

(i) Use the average bond enthalpies to deduce a value for the enthalpy of
hydrogenation of cyclohexene.

...........................................................................................................................

...........................................................................................................................
(1)

IB Questionbank Chemistry 16
 (ii) The percentage difference between these two methods (average bond enthalpies
and enthalpies of combustion) is greater for cyclohexene than it was for ethene.
John’s hypothesis was that it would be the same. Determine why the use of average
bond enthalpies is less accurate for the cyclohexene equation shown above, than it
was for ethene. Deduce what extra information is needed to provide a more
accurate answer.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)
(Total 7 marks)

27. Two students were asked to use information from the Data Booklet to calculate a value for the
enthalpy of hydrogenation of ethene to form ethane.

C2H4(g) + H2(g) → C2H6(g)

John used the average bond enthalpies from Table 10. Marit used the values of enthalpies of
combustion from Table 12.

(a) Calculate the value for the enthalpy of hydrogenation of ethene obtained using the
average bond enthalpies given in Table 10.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Chemistry 17
 (b) Determine the value for the enthalpy of hydrogenation of ethene using the values for the
enthalpies of combustion of ethene, hydrogen and ethane given in Table 12.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(c) Suggest one reason why John’s answer is slightly less accurate than Marit’s answer and
calculate the percentage difference.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(d) John then decided to determine the enthalpy of hydrogenation of cyclohexene to produce
cyclohexane.

C6H10(l) + H2(g) → C6H12(l)

(i) Use the average bond enthalpies to deduce a value for the enthalpy of
hydrogenation of cyclohexene.

...........................................................................................................................

...........................................................................................................................
(1)

IB Questionbank Chemistry 18
 (ii) The percentage difference between these two methods (average bond enthalpies
and enthalpies of combustion) is greater for cyclohexene than it was for ethene.
John’s hypothesis was that it would be the same. Determine why the use of average
bond enthalpies is less accurate for the cyclohexene equation shown above, than it
was for ethene. Deduce what extra information is needed to provide a more
accurate answer.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)
(Total 9 marks)

28. Propane can be formed by the hydrogenation of propene.

CH3CH=CH2(g) + H2(g) → CH3CH2CH3(g)

(i) State the conditions necessary for the hydrogenation reaction to occur.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(ii) Enthalpy changes can be determined using average bond enthalpies. Define the term
average bond enthalpy.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Chemistry 19
 (iii) Determine a value for the hydrogenation of propene using information from Table 10 of
the Data Booklet.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(iv) Explain why the enthalpy of hydrogenation of propene is an exothermic process.

......................................................................................................................................

......................................................................................................................................
(1)
(Total 7 marks)

IB Questionbank Chemistry 20