Structure 1. Models of the particulate nature of matter

1.1 Introduction to the particulate nature of matter

1.2 The nuclear atom

1.3 Electron configurations

1.4 The mole

1.5 Ideal gases

Structure 2. Models of bonding and structure

2.1 The ionic model

2.2 The covalent model

2.3 The metallic model

2.4 From models to materials

Structure 3. Classification of matter

3.1 The periodic table

3.2 Functional groups: Organic compounds

Reactivity 1. What drives chemical reactions?

1.1 Measuring enthalpy changes

1.2 Energy cycles

1.3 Energy from fuels

Reactivity 2. How much, how fast and how far?

2.1 Amount of chemical change

2.2 Rate of chemical change

2.3 Extent of chemical change

Reactivity 3. What are the mechanisms of chemical change?

3.1 Proton transfer reactions

3.2 Electron transfer reactions

3.3 Electron sharing reactions (Radicals)

3.4 Electron-pair sharing reactions

IB Chemistry HL 1.2 Energy cycles Question Bank

[Maximum number: 4]

Ethane-1,2-diol, $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ , has a wide variety of uses including the removal of ice from aircraft and heat transfer in a solar cell.

(a)

Ethane-1,2-diol can be formed according to the following reaction.

2 \mathrm{CO}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}(\mathrm{~g})

[ 3 ]

(i)

Calculate the enthalpy change, $\Delta H^{\ominus}$ , in kJ , for this reaction using section 11 of the data booklet. The bond enthalpy of the carbon-oxygen bond in CO(g) is $1077 \mathrm{~kJ} \mathrm{~mol}^{-1}$ .

[ 3 ]

(b)

(i)

Calculate $\Delta H^{\ominus}$ , in kJ , for this similar reaction below using $\Delta H_{\mathrm{f}}^{\ominus}$ data from section 12 of the data booklet. $\Delta H_{\mathrm{f}}^{\ominus}$ of $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}(\mathrm{l})$ is $-454.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$ .

2 \mathrm{CO}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}(\mathrm{l})

[ 1 ]

[Maximum number: 2]

Ammonium nitrate, $\mathrm{NH}_{4} \mathrm{NO}_{3}$ , is used as a high nitrogen fertilizer.

(a)

Solid ammonium nitrate can decompose to gaseous dinitrogen monoxide and liquid water.

[ 2 ]

(i)

Calculate the standard enthalpy change, $\Delta H^{\ominus}$ , of the reaction. Use section 12 of the data booklet.

\begin{aligned} & \Delta H_{\mathrm{f}}^{\ominus} \text { ammonium nitrate }=-366 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ & \Delta H_{\mathrm{f}}^{\ominus} \text { dinitrogen monoxide }=82 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{aligned}

[ 2 ]

[Maximum number: 3]

Ethyne, $\mathrm{C}_{2} \mathrm{H}_{2}$ , reacts with oxygen in welding torches.

(a)

Ethyne reacts with steam.

\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}(\mathrm{~g})

Two possible products are:

[ 3 ]

(i)

Determine the enthalpy change for the reaction, in kJ , to produce A using section 11 of the data booklet.

[ 3 ]

(a)

The students repeated the experiment using 6.16 g of solid hydrated magnesium sulfate, $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ , and $50.0 \mathrm{~cm}^{3}$ of water. They found the enthalpy change, $\Delta H_{2}$ , to be $+18 \mathrm{~kJ} \mathrm{~mol}^{-1}$ .

The enthalpy of hydration of solid anhydrous magnesium sulfate is difficult to determine experimentally, but can be determined using the diagram below.

[ 1 ]

(i)

Determine the enthalpy change, $\Delta H$ , in $\mathrm{kJ} \mathrm{mol}^{-1}$ , for the hydration of solid anhydrous magnesium sulfate, $\mathrm{MgSO}_{4}$ .

[ 1 ]

[Maximum number: 8]

The reaction between ethene and steam is used in the industrial production of ethanol.

\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{~g})

The enthalpy change of the reaction can be calculated either by using average bond enthalpies or by using standard enthalpies of formation.

(a)

Determine the enthalpy change of the reaction, in $\mathrm{kJ} \mathrm{mol}^{-1}$ , using the average bond enthalpies in Table 10 of the Data Booklet.

[ 3 ]

(b)

(i)

Define the term standard enthalpy change of formation.

[ 2 ]

(ii)

Determine the enthalpy change of the reaction, in $\mathrm{kJ} \mathrm{mol}^{-1}$ , between ethene and steam using the enthalpy change of formation values given below.

[ 2 ]

(c)

Comment on which of the values obtained in (a) and (b)(ii) is more accurate, giving a reason.

[ 1 ]

[Maximum number: 1]

Nitrogen (IV) oxide, $\mathrm{NO}_{2}$ , is a brown gas found in photochemical smog and has a pollutant causing acid deposition.

(a)

Nitrogen (IV) oxide exists in equilibrium with dinitrogen tetroxide, $\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g})$ , which is colourless.

2 \mathrm{NO}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g})

[ 1 ]

(i)

Calculate the standard enthalpy change, in $\mathrm{kJ} \mathrm{mol}^{-1}$ , for the reaction:

\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g}) \rightarrow 2 \mathrm{NO}_{2}(\mathrm{~g})

[ 1 ]

White phosphorus is an allotrope of phosphorus and exists as $\mathrm{P}_{4}$ .

(a)

An equilibrium exists between $\mathrm{PCl}_{3}$ and $\mathrm{PCl}_{5}$ .

\mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{PCl}_{5}(\mathrm{~g})

(i)

Calculate the standard enthalpy change $\left(\Delta H^{\ominus}\right)$ for the forward reaction in $\mathrm{kJ} \mathrm{mol}^{-1}$ .

\begin{aligned} \Delta H^{\ominus}{ }_{\mathrm{f}} \mathrm{PCl}_{3}(\mathrm{~g}) & =-306.4 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ \Delta H^{\ominus}{ }_{\mathrm{f}} \mathrm{PCl}_{5}(\mathrm{~g}) & =-398.9 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{aligned}

[Maximum number: 4]

Methanoic acid can be produced by the hydrogenation of carbon dioxide according to the equilibrium

\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{HCOOH}(\mathrm{~g})

(a)

Bond enthalpies are a useful way of finding approximate enthalpy changes for reactions.

[ 4 ]

(i)

Determine the enthalpy change, $\Delta H^{\ominus}$ , of this reaction, using section 11 of the data booklet.

[ 3 ]

(ii)

Bond enthalpies are usually only approximate values. Identify which of the bond enthalpies you have just used is actually an exact value, and give a reason for your choice.

[ 1 ]

[Maximum number: 4]

Methanoic acid can be produced by the hydrogenation of carbon dioxide according to the equilibrium

\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{HCOOH}(\mathrm{~g})

(a)

Bond enthalpies are a useful way of finding approximate enthalpy changes for reactions.

[ 4 ]

(i)

Determine the enthalpy change, $\Delta H^{\ominus}$ , of this reaction, using section 11 of the data booklet.

[ 3 ]

(ii)

Bond enthalpies are usually only approximate values. Identify which of the bond enthalpies you have just used is actually an exact value, and give a reason for your choice.

[ 1 ]

[Maximum number: 1]

What is the enthalpy of combustion, $\Delta H_{\mathrm{c}}$ , of ethanol in $\mathrm{kJ} \mathrm{mol}^{-1}$ ?

Maximum temperature of water: $30.0^{\circ} \mathrm{C}$
Initial temperature of water: $20.0^{\circ} \mathrm{C}$
Mass of water in beaker: 100.0 g
Loss in mass of ethanol: 0.230 g
$M_{\mathrm{r}}$ (ethanol): 46.08
Specific heat capacity of water: $4.18 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}$ $q=m c \Delta T$

$-\frac{100.0 \times 4.18 \times(10.0+273)}{\frac{0.230}{46.08} \times 1000}$

$-\frac{0.230 \times 4.18 \times 10.0}{\frac{100.0}{46.08} \times 1000}$

$-\frac{100.0 \times 4.18 \times 10.0}{\frac{0.230}{46.08} \times 1000}$

$-\frac{100.0 \times 4.18 \times 10.0}{\frac{0.230}{46.08}}$

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Question 1

Question 1(a)

Question 1(a)(iii)

Question 1(b)

Question 1(b)(i)

Question 1

Question 1(f)

Question 1(f)(iii)

Question 1

Question 1(c)

Question 1(c)(ii)

Question 1

Question 1(b)

Question 1(b)(i)

Question 2

Question 2(a)

Question 2(b)

Question 2(b)(i)

Question 2(b)(ii)

Question 2(c)

Question 2

Question 2(a)

Question 2(a)(iv)

Question 3

Question 3(c)

Question 3(c)(i)

Question 2

Question 2(c)

Question 2(c)(i)

Question 2(c)(iii)

Question 2

Question 2(c)

Question 2(c)(i)

Question 2(c)(iii)

Question 14