Free Printable IB Chemistry Topic 5

1.

This question is about an experiment to measure the enthalpy of combustion, ΔH_c, of ethanol, using the apparatus and setup shown. Which quantity is likely to be the most inaccurate due to the sources of error in this experiment?

a)

Mass of ethanol burnt

b)

Molecular mass of ethanol

c)

Mass of water

d)

Temperature change

2.

When equal masses of X and Y absorb the same amount of energy, their temperatures rise by 5 °C and 10 °C respectively. Which is correct?

a)

The specific heat capacity of X is twice that of Y.

b)

The specific heat capacity of X is half that of Y.

c)

The specific heat capacity of X is one fifth that of Y.

d)

The specific heat capacity of X is the same as Y.

3.

Which is correct when Ba(OH)₂ reacts with NH₄Cl?

a)

A

b)

B

c)

C

d)

D

4.

The enthalpy of combustion of ethanol is determined by heating a known mass of tap water in a glass beaker with a flame of burning ethanol. Which will lead to the greatest error in the final result?

a)

Assuming the density of tap water is 1.0 g cm⁻³

b)

Assuming all the energy from the combustion will heat the water.

c)

Assuming the specific heat capacity of the tap water is 4.18 J g⁻¹ K⁻¹

d)

Assuming the specific heat capacity of the beaker is negligible

5.

Two 100 cm³ aqueous solutions, one containing 0.010 mol NaOH and the other 0.010 mol HCl, are at the same temperature.

When the two solutions are mixed the temperature rises by y °C.

Assume the density of the final solution is 1.00 g cm⁻³.

Specific heat capacity of water = 4.18 J g⁻¹ K⁻¹

What is the enthalpy change of neutralization in kJ mol⁻¹?

a)

A

b)

B

c)

C

d)

D

6.

Which statement is correct for this reaction?

Fe₂O₃ (s) + 3CO (g) → 2Fe (s) + 3CO₂ (g) ΔH = −26.6 kJ

a)

13.3 kJ are released for every mole of Fe produced.

b)

26.6 kJ are absorbed for every mole of Fe produced.

c)

53.2 kJ are released for every mole of Fe produced.

d)

26.6 kJ are released for every mole of Fe produced.

7.

Which expression gives the mass, in g, of ethanol (C₂H₆O)required to produce 683.5 kJ of heat upon complete combustion?

(M_r for ethanol = 46.0, ΔH^θ_c=−1367 kJmol⁻¹)

a)

A

b)

B

c)

C

d)

D

8.

The combustion of glucose is exothermic and occurs according to the following equation:

C₆H₁₂O₆ (s) + 6O₂ (g) → 6CO₂ (g) + 6H₂O (g)

Which is correct for this reaction?

a)

A

b)

B

c)

C

d)

D

9.

The enthalpy change for the dissolution of NH₄NO₃ is +26 kJ mol^–1 at 25 °C. Which statement about this reaction is correct?

a)

The reaction is exothermic and the solubility decreases at higher temperature.

b)

The reaction is exothermic and the solubility increases at higher temperature.

c)

The reaction is endothermic and the solubility decreases at higher temperature.

d)

The reaction is endothermic and the solubility increases at higher temperature.

10.

Which change of state is exothermic?

a)

CO₂(s) → CO₂(g)

b)

H₂O(l) → H₂O(g)

c)

NH₃(g) → NH₃(l)

d)

Fe(s) → Fe(l)

11.

When 25.0cm³ 0.100moldm⁻³ NaOH(aq) is mixed with 25.0cm³ 0.100moldm⁻³ HCl(aq) at the same temperature, a temperature rise, ∆T, is recorded. What is the expression, in kJ mol⁻¹, for the enthalpy of neutralisation? (Assume the density of the mixture = 1.00 g cm⁻³ and its specific heat capacity=4.18kJkg⁻¹K⁻¹ =4.18Jg⁻¹K⁻¹)

a)

A

b)

B

c)

C

d)

D

12.

5.35g of solid ammonium chloride, NH₄Cl(s), was added to water to form 25.0g of solution. The maximum decrease in temperature was 14 K. What is the enthalpy change, in kJmol^-1, for this reaction? (Molar mass of NH₄Cl = 53.5gmol^-1; the specific heat capacity of the solution is 4.18 Jg^-1K^-1)

a)

A

b)

B

c)

C

d)

D

13.

Which processes are exothermic?

I. CH₃COOH (aq) + NaOH (aq) → CH₃COONa (aq) + H₂O(l)

II. 2C (s) + O₂(g) → 2CO (g)

III. C (s) + O₂(g) → CO2 (g)

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

14.

Which combination is correct for the standard enthalpy change of neutralization?

a)

A

b)

B

c)

C

d)

D

15.

The same amount of heat energy is added to 1.00 g of each substance. Which statement is correct if all the substances are at the same temperature before the heat energy is added?

a)

Copper will reach the highest temperature.

b)

Water will reach the highest temperature.

c)

All four substances will reach the same temperature.

d)

Aluminium will reach a higher temperature than sodium chloride.

16.

The enthalpy change for the reaction between zinc metal and copper(II) sulfate solution is −217 kJmol⁻¹. Which statement about this reaction is correct?

a)

The reaction is endothermic and the temperature of the reaction mixture initially rises.

b)

The reaction is endothermic and the temperature of the reaction mixture initially drops.

c)

The reaction is exothermic and the temperature of the reaction mixture initially rises.

d)

The reaction is exothermic and the temperature of the reaction mixture initially drops.

17.

Which statement is correct for the reaction with this enthalpy level diagram?

a)

Heat energy is released during the reaction and the reactants are more stable than the products.

b)

Heat energy is absorbed during the reaction and the reactants are more stable than the products.

c)

Heat energy is released during the reaction and the products are more stable than the reactants.

d)

Heat energy is absorbed during the reaction and the products are more stable than the reactants.

18.

The specific heat capacities of two substances are given in the table below. Which statement is correct?

a)

More heat is needed to increase the temperature of 50 g of water by 50 °C than 50 g of ethanol by 50 °C.

b)

If the same heat is supplied to equal masses of ethanol and water, the temperature of the water increases more.

c)

If equal masses of water at 20 °C and ethanol at 50 °C are mixed, the final temperature is 35 °C .

d)

If equal masses of water and ethanol at 50 °C cool down to room temperature, ethanol liberates more heat.

19.

The table shows information about temperature increases when an acid and an alkali are mixed. What is the value of y?

a)

12x

b)

x

c)

2x

d)

4x

20.

What is the value of ΔH for the exothermic reaction represented by the diagram below?

a)

y - z

b)

z - y

c)

x - z

d)

z - x

21.

What is the temperature rise when 2100 J of energy is supplied to 100 g of water?

(Specific heat capacity of water =4.2 Jg⁻¹K⁻¹)

a)

5°C

b)

278 K

c)

0.2°C

d)

20°C

22.

Which processes are exothermic?

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

23.

Which statements are correct for an exothermic reaction?

I. The products are more stable than the reactants.

II. The enthalpy change, ΔH, is negative.

III. The temperature of the surroundings increases.

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

24.

The specific heat capacity of aluminium is 0.900 Jg⁻¹K⁻¹. What is the heat energy change, in J, when 10.0 g of aluminium is heated and its temperature increases from 15.0 °C to 35.0 °C?

a)

+180

b)

+315

c)

+1800

d)

+2637

25.

Which ionic compound has the most endothermic lattice enthalpy?

a)

Sodium chloride

b)

Sodium oxide

c)

Magnesium chloride

d)

Magnesium oxide

26.

Which process is endothermic?

a)

A

b)

B

c)

C

d)

D

27.

Which reaction has an enthalpy change equal to the standard enthalpy change of combustion?

a)

A

b)

B

c)

C

d)

D

28.

Which combination is correct for the exothermic reaction that occurs between zinc and copper sulfate solution.

a)

A

b)

B

c)

C

d)

D

29.

A 5.00 g sample of a substance was heated from 25.0 °C to 35.0 °C using 2.00 x 10² J of energy. What is the specific heat capacity of the substance in Jg^-1K^-1? ?

a)

4.00 x 10^-3

b)

2.50 x 10^-1

c)

2

d)

4

30.

Using a calorimeter the enthalpy change for the combustion of ethanol was found to be −867 kJmol⁻¹. The Data Booklet value is −1367 kJmol⁻¹. During the experiment some black soot formed.Which statements are correct?

I. The percentage error for the experiment can be calculated as follows: (1367−867)×100%

II. The difference between the two values may be due to heat loss to the surroundings.

III. The black soot suggests that incomplete combustion occurred.

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

31.

Which process is endothermic?

a)

A

b)

B

c)

C

d)

D

32.

When 100cm³ 1.0moldm^-3 of HCl is mixed with 100 cm³ of 1.0 moldm^-3of NaOH, the temperature of the resulting solution increases by 5.0 °C. What will be the temperature change, in °C, when 50cm3 of these two solutions are mixed?

a)

2.5

b)

5.0

c)

10

d)

20

33.

Which processes have a negative enthalpy change?

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

34.

At 25 °C, 200cm³ of 1.00 moldm^-3nitric acid is added to 5.0 g of magnesium powder. If the experiment is repeated using the same mass of magnesium powder, which conditions will result in the same initial reaction rate?

a)

A

b)

B

c)

C

d)

D

35.

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.

36.

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.

37.

Which is correct about energy changes during bond breaking and bond formation?

a)

A

b)

B

c)

C

d)

D

38.

Which processes are exothermic?

I. Ice melting

II. Neutralization

III. Combustion

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

39.

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

a)

A

b)

B

c)

C

d)

D

40.

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

a)

The reaction is exothermic and ΔH

is negative.

b)

The reaction is exothermic and ΔH

is positive.

c)

The reaction is endothermic and ΔH

is negative.

d)

The reaction is endothermic and ΔH

is positive.

41.

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

42.

What is the energy, in kJ, released when 1.00 mol of carbon monoxide is burned according to the following equation?
$2CO(g)+O_2(g)\ →\ 2CO_2(g):\ ΔH^Θ=−564kJ$

a)

141

b)

282

c)

564

d)

1128

43.

The specific heat of iron is 0.450Jg^-1K^-1 . What is the energy, in J, needed to increase the temperature of 50.0 g of iron by 20.0 K?

a)

9.00

b)

22.5

c)

45.0

d)

450

44.

Which of the following reactions are exothermic?

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

45.

1.0 g of sodium hydroxide, NaOH, was added to 99.0 g of water. The temperature of the solution increased from 18.0 °C to 20.5 °C. The specific heat capacity of the solution is 4.18Jg^-1K^-1. Which expression gives the heat evolved in kJmol−1?

a)

$\frac{2.5\times100\times4.18\times1000}{40.0}$

b)

$\frac{2.5\times100\times4.18}{1000\times40.0}$

c)

$\frac{2.5\times100.0\times4.18\times40.0}{1000}$

d)

$\frac{2.5\times100\times4.18\times40.0}{1000}$

46.

What is the enthalpy change of the reaction?

C₆H₁₄ (l) → C₂H₄ (g) + C₄H₁₀ (g)

a)

+ 1411 + 2878 + 4163

b)

+ 1411 − 2878 − 4163

c)

+ 1411 + 2878 − 4163

d)

− 1411 − 2878 + 4163

47.

What is the enthalpy change of reaction for the following equation?

a)

x + y + z

b)

−x − y + z

c)

x − y − z

d)

x − y + z

48.

Consider the following equations.

2Al (s) + 32

O₂ (g) → Al₂O₃ (s) ΔH^Ɵ = −1670 kJ

Mn (s) + O₂ (g) → MnO₂ (s) ΔH^Ɵ = −520 kJ

What is the standard enthalpy change, in kJ, of the reaction below?

4Al (s) + 3MnO₂ (s) → 2Al₂O₃ (s) + 3Mn (s)

a)

−1670 + 520

b)

32(−1670) + 3(520)

c)

2(−1670) + 3(−520)

d)

2(−1670) + 3(520)

49.

Consider the following equations.

2Al (s) + 3/2 O₂ (g) → Al₂O₃ (s) ΔH^Ɵ = −1670 kJ

Mn (s) + O₂ (g) → MnO₂ (s) ΔH^Ɵ = −520 kJ

What is the standard enthalpy change, in kJ, of the reaction below?

4Al (s) + 3MnO₂ (s) → 2Al₂O₃ (s) + 3Mn (s)

a)

−1670 + 520

b)

32(−1670) + 3(520)

c)

2(−1670) + 3(−520)

d)

2(−1670) + 3(520)

50.

What is the enthalpy change of reaction for the following equation?

C₂H₄ (g) + H₂ (g) → C₂H₆ (g)

C₂H₄ (g) + 3O₂ (g) → 2CO₂ (g) + 2H₂O (l) ΔH = x

C₂H₆ (g) + 7/2 O₂ (g) → 2CO₂ (g) + 3H₂O (l) ΔH = y

H₂ (g) + 1/2 O₂ (g) → H₂O (l) ΔH = z

a)

x + y + z

b)

−x − y + z

c)

x − y − z

d)

x − y + z

51.

Consider the following reactions:

Fe₂O₃ (s) + CO (g) → 2FeO (s) + CO₂ (g) ΔH^Θ = −3 kJ

Fe (s) + CO₂ (g) → FeO (s) + CO (g) ΔH^Θ = +11 kJ

What is the ΔH^Θ value, in kJ, for the following reaction?

Fe₂O₃ (s) + 3CO (g) → 2Fe (s) + 3CO₂ (g)

a)

-25

b)

-14

c)

+8

d)

+19

52.

What is the enthalpy of combustion of butane in kJ mol⁻¹?

2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(l)

a)

4x + 5y − z

b)

4x + 5y + z

c)

8x + 10y − 2z

d)

8x + 5y + 2z

53.

What is the enthalpy change of combustion of urea, (NH₂)₂CO, in kJ mol⁻¹?

2(NH₂)₂CO(s) + 3O₂(g) → 2CO₂(g) + 2N₂(g) + 4H₂O(l)

a)

2 × (−333) −2 × (−394) −4 × (−286)

b)

1/2 [2 × (−394) + 4 × (−286) −2 × (−333)]

c)

2 × (−394) + 4 × (−286) −2 × (−333)

d)

1/2 [2 × (−333) −2 × (−394) −4 × (−286)]

54.

The enthalpy changes for two reactions are given.

Br₂ (l) + F₂ (g) → 2BrF (g) ΔH = x kJ

Br₂ (l) + 3F₂ (g) → 2BrF₃ (g) ΔH = y kJ

What is the enthalpy change for the following reaction?

BrF (g) + F₂ (g) → BrF₃ (g)

a)

x – y

b)

–x + y

c)

1/2 (–x + y)

d)

1/2 (x – y)

55.

Which expression gives the enthalpy change, ΔH, for the thermal decomposition of calcium carbonate?

a)

ΔH = ΔH₁ − ΔH₂

b)

ΔH = 2ΔH₁ − ΔH₂

c)

ΔH = ΔH₁ − 2ΔH₂

d)

ΔH = ΔH₁ + ΔH₂

56.

Why is the value of the enthalpy change of this reaction calculated from bond enthalpy data less accurate than that calculated from standard enthalpies of formation?

2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(g)

a)

All the reactants and products are gases.

b)

Bond enthalpy data are average values for many compounds.

c)

Elements do not have standard enthalpy of formation.

d)

Standard enthalpies of formation are per mole.

57.

Hydrazine reacts with oxygen.

N₂H₄(l) + O₂(g) → N₂(g) + 2H₂O(l) ΔH^θ = -623 kJ

What is the standard enthalpy of formation of N₂H₄(l) in kJ? The standard enthalpy of formation of H₂O(l) is -286 kJ.

a)

-623 - 286

b)

-623 + 572

c)

-572 + 623

d)

-286 + 623

58.

What is the enthalpy of formation of ethyne, in kJmol⁻¹, represented by the arrow Y on the diagram?

a)

−788−286+1301

b)

−788−286−1301

c)

+788+286−1301

d)

+788+286+1301

59.

The equation for the formation of ethyne is:

2C(s) + H₂ (g) → C₂H₂ (g)

What is the enthalpy change, in kJ, for this reaction using the enthalpy of combustion data below?

a)

2 × (−394) + 1/2 (−572) − 1/2 (−2602)

b)

2 × (−394) + (−572) − (−2602)

c)

2 × (−394) + 1/2 (−572) + 1/2 (−2602)

d)

2 × (−394) + (−572) + (−2602)

60.

When four moles of aluminium and four moles of iron combine with oxygen to form their oxides, the enthalpy changes are –3338 kJ and –1644 kJ respectively.

4Al(s)+3O₂(g)→2Al₂O₃(s): ΔH=−3338 kJ

4Fe(s)+3O₂(g)→2Fe2₂O₃(s): ΔH=−1644 kJ

What is the enthalpy change, in kJ, for the reduction of one mole of iron(III) oxide by aluminium?

Fe₂O₃(s)+2Al(s)→2Fe(s)+Al₂O₃(s)

a)

+1694

b)

+847

c)

-847

d)

-1694

61.

Consider the following equations.
$2Fe(s)+1\frac{1}{2}O_2(g)→Fe_2O_3(s):\ \ \ ΔH^Θ=x$
$CO(g)+\frac{1}{2}O_2(g)→CO_2(g):\ \ ΔH^Θ=y$

What is the enthalpy change of the reaction below?
$Fe_2O_3(s)+3CO(g)→3CO_2(g)+2Fe(s)$

a)

3y − x

b)

3y + x

c)

−3y − x

d)

−3y + x

62.

Consider the following two equations.
$2Ca(s)+O_2(g)→2CaO(s)$
$ΔH^Θ=+x\ kJ$

$Ca(s)+0.5O_2(g)+CO_2(g)→CaCO_3(s)$
$ΔH^Θ=+y\ kJ$

What is the enthalpy change, in kJ, for the following reaction?
$CaO(s)+CO_2(g)→CaCO_3(s)$

a)

y - 0.5x

b)

y - x

c)

0.5 - y

d)

x - y

63.

Enthalpy changes of reaction are provided for the following reactions.
$2C(s)+2H_2(g)→C_2H_4(g)$
$ΔH^Θ=+52kJmol^{−1}$
$2C(s)+3H_2(g)→C_2H_6(g)$
$ΔH^Θ=-85kJmol^{−1}$

What is the enthalpy change, in kJmol−1, for the reaction between ethene and hydrogen?
$C_2H_4(g)+H_2(g)→C_2H_6(g)$

a)

-137

b)

-33

c)

+33

d)

+137

64.

Using the equations below:
$C(s)+O_2(g)→CO_2(g):\ ΔH^Θ=−390kJ$
$H_2(g)+\frac{1}{2}O_2(g)→H_2O(l):ΔH^Θ=−286kJ\$
$CH_4(g)+2O_2(g)→CO_2(g)+2H_2O(l)$
$ΔH^Θ=−890kJ$
what is the standard enthalpy change, in kJ, for the following reaction?
$C(s)+2H_2(g)→CH_4(g)$

a)

-214

b)

-72

c)

+72

d)

+214

65.

Consider these equations:
What is the standard enthalpy change, in kJ, for the following reaction?
$N_2(g)+2H_2(g)→N_2H_4(g)$

a)

-95.4

b)

-5.80

c)

+5.80

d)

+95.4

66.

Consider the above enthalpy of combustion data.
What is the enthalpy of formation of ethane in kJmol−1?
$2C(s)+3H_2(g)→C_2H_6(g)$

a)

[(−x) + (−y)] − (−z)

b)

(−z) − [(−x) + (−y)]

c)

[(−2x) + (−3y)] − (−z)

d)

(−z) − [(−2x) + (−3y)]

67.

Consider the above reactions. What is the standard enthalpy change value, in kJ, for this reaction?
$Cu(s)+\frac{1}{2}O2(g)→CuO(s)$

a)

−144 + 11

b)

+144 − 11

c)

−144 − 11

d)

+144 + 11

68.

Consider the above reactions. What is the standard enthalpy change value, in kJ, for the following reaction?
$N_2(g)+2O_2(g)→2NO_2(g)$

a)

−1 × (+180) + −1 × (+112)

b)

−1 × (+180) + 1 × (+112)

c)

1 × (+180) + −1 × (+112)

d)

1 × (+180) + 1 × (+112)

69.

Consider the two reactions involving iron and oxygen.
What is the enthalpy change, in kJ, for the reaction below?
$4FeO(s)+O_2(g)→2Fe_2O_3(s)$

a)

−1648 − 2(−544)

b)

−544 − (−1648)

c)

−1648 − 544

d)

−1648 − 2(544)

70.

The standard enthalpy changes for the combustion of carbon and carbon monoxide are shown below.
What is the standard enthalpy change, in kJ, for the following reaction?
$C(s)+\frac{1}{2}O_2(g)→CO(g)$

a)

-677

b)

-111

c)

+111

d)

+677

71.

Consider the equations above. What is the enthalpy change of the reaction below?
$2CH_4(g)+3\frac{1}{2}O_2(g)→(COOH)_2(s)+3H_2O(l$

a)

x + y + z

b)

x + y + z

c)

2x + 2y + z

d)

2x + 2y + 2z

72.

Given the enthalpy change for the reaction above:
$2H_2(g)+O_2(g)→2H_2O(l):\ ΔH^Θ=−572kJ$
which statement is correct?

a)

The standard enthalpy change of combustion of H2(g)

is −286 kJmol−1.

b)

The standard enthalpy change of combustion of H2(g)

is +286 kJmol−1.

c)

The standard enthalpy change of formation of H2O(l)

is −572 kJmol−1.

d)

The standard enthalpy change of formation of H2O(l)

is +572 kJmol−1.

73.

Which equation represents the N–H bond enthalpy in NH₃?

a)

$NH_3(g)\ →\ N(g)+3H(g)$

b)

$\frac{1}{3}NH_3(g)→\ \frac{1}{3}N(g)+H(g)$

c)

$NH_3(g)\ →\ \frac{1}{2}N_2(g)+\frac{3}{2}H_2(g)$

d)

$NH3(g)\ →\ •NH_2(g)+•H(g)$

74.

Which is correct for the reaction?

2Al(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)

ΔH = −1049 kJ

a)

Reactants are less stable than products and the reaction is endothermic.

b)

Reactants are more stable than products and the reaction is endothermic.

c)

Reactants are more stable than products and the reaction is exothermic.

d)

Reactants are less stable than products and the reaction is exothermic.

75.

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

a)

[2(1077) + 4(463)] − [2(414) + 3(498)]

b)

[2(414) + 3(498)] − [2(1077) + 4(463)]

c)

[8(414) + 3(498)] − [2(1077) + 8(463)]

d)

[2(1077) + 8(463)] − [8(414) + 3(498)]

76.

Consider the following reaction:

N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)

Which calculation gives ΔH^Θ, in kJ, for the forward reaction?

a)

2z − y − 3x

b)

y + 3x − 2z

c)

y + 3x − 6z

d)

6z − y − 3x

77.

Which statement is correct?

a)

In an exothermic reaction, the products have more energy than the reactants.

b)

In an exothermic reversible reaction, the activation energy of the forward reaction is greater than that of the reverse reaction.

c)

In an endothermic reaction, the products are more stable than the reactants.

d)

In an endothermic reversible reaction, the activation energy of the forward reaction is greater than that of the reverse reaction.

78.

Which describes the reaction shown in the potential energy profile?

a)

The reaction is endothermic and the products have greater enthalpy than the reactants.

b)

The reaction is endothermic and the reactants have greater enthalpy than the products.

c)

The reaction is exothermic and the products have greater enthalpy than the reactants.

d)

The reaction is exothermic and the reactants have greater enthalpy than the products.

79.

What is the enthalpy change, in kJ, of the following reaction?

3H₂ (g) + N₂ (g) ⇌ 2NH₃ (g)

a)

(6 × 391) − [(3 × 436) + 945]

b)

(3 × 391) − (436 + 945)

c)

−[(3 × 436) + 945] + (3 × 391)

d)

−(6 × 391) + [(3 × 436) + 945]

80.

In which order does the oxygen–oxygen bond enthalpy increase?

a)

H₂O₂ < O₂ < O₃

b)

H₂O₂ < O₃ < O₂

c)

O₂ < O₃ < H₂O₂

d)

O₃ < H₂O₂ < O₂

81.

What can be deduced from this reaction profile?

a)

The reactants are less stable than the products and the reaction is exothermic.

b)

The reactants are less stable than the products and the reaction is endothermic.

c)

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

d)

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

82.

What can be deduced from the facts that ozone absorbs UV radiation in the region of 340 nm and molecular oxygen in the region of 242 nm?

a)

The bond between atoms in molecular oxygen is a double bond.

b)

The bonds in ozone are delocalized.

c)

The bonds between atoms in ozone are stronger than those in molecular oxygen.

d)

The bonds between atoms in molecular oxygen need more energy to break.

83.

A student measured the temperature of a reaction mixture over time using a temperature probe. By considering the graph, which of the following deductions can be made?

I. The reaction is exothermic.

II. The products are more stable than the reactants.

III. The reactant bonds are stronger than the product bonds.

a)

I and II only

b)

I and III only

c)

II and III only

d)

I, II and III

84.

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.

85.

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

a)

A

b)

B

c)

C

d)

D

86.

Which equation best represents the bond enthalpy of HCl?

a)

A

b)

B

c)

C

d)

D

IB Chemistry Topic 5

Total questions: 86

Worksheet time: 13hrs 41mins

Similar Resources on Wayground