A Level Chemistry 9701 Paper 22, May/June 2023

State the type of bonding present in magnesium and in sodium chloride. bonding in magnesium ...................................................................................................... bonding in sodium chloride ...............................................................................................

Explain the difference in the melting points of magnesium and sodium chloride.

Explain the difference in the melting points of phosphorus and sulfur in terms of structure and bonding.

Define electronegativity.

Explain why electronegativity increases across a period.

Name the strongest intermolecular force that exists between ${\mathrm{N}\mathrm{H}}_3(\mathrm{l})$ molecules.

Draw a diagram to show the formation of the strongest intermolecular force between two molecules of ${\mathrm{N}\mathrm{H}}_3(\mathrm{l})$. Include any relevant lone pairs of electrons and dipoles.

The melting points of ice and ammonia are shown in Table 1.2. Table 1.2

Suggest two reasons for the difference in the melting points of ice and ammonia.

Complete Table 2.1 to show the maximum oxidation number of the elements Na to P in their chlorides. Table 2.1

State what determines the maximum oxidation number of elements in Period 3.

An excess of cold water is added to the chloride of silicon. Write an equation for the reaction between an excess of cold water and the chloride of silicon.

Suggest the pH of the solution produced in (b)(i).

An excess of cold water is added to the chloride of phosphorus. Write an equation for the reaction between an excess of cold water and the chloride of phosphorus.

Suggest the pH of the solution produced in (c)(i).

Write an equation for the reaction of chlorine with water.

Write an equation for the reaction of chlorine with hot $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$.

Bleach is used as a cleaning product to kill bacteria. It is made by adding compounds like sodium chlorate(I), $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}\mathrm{O}$, to water. Identify the formula of the ion present in bleach that kills bacteria.

Sodium chlorate(I), $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}\mathrm{O}$, reacts with hydrogen peroxide to produce sodium chloride, water and oxygen gas. Construct an equation for this reaction.

A sample of bleach $\mathbf{W}$ contains an unknown concentration of sodium chlorate(I). $10.0{\mathrm{c}\mathrm{m}}^3$ of $\mathbf{W}$ is diluted with distilled water to make a total volume of $100{\mathrm{c}\mathrm{m}}^3$ of bleach solution. $25.0{\mathrm{c}\mathrm{m}}^3$ of this diluted bleach solution is added to an excess of hydrogen peroxide and the volume of gas produced measured under room conditions. The experiment is repeated and on average $25.0{\mathrm{c}\mathrm{m}}^3$ of diluted bleach solution produces $42.0{\mathrm{c}\mathrm{m}}^3$ of gas. Calculate the concentration, in $\mathrm{g}{\mathrm{d}\mathrm{m}}^{-3}$, of sodium chlorate(I) in $\mathbf{W}$.

State the reagent and conditions for step 1 in Fig. 3.1.

Give the systematic name of $\mathbf{X}$.

Identify the type of reaction that occurs when dilute acid is added to $\mathbf{X}$ in step 2.

In step 3, $\mathbf{Y}$ and a gas are produced. Construct an equation for step 3.

${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$ can also be formed from propan-1-ol and potassium dichromate(VI). State the conditions required.

Complete Table 3.1 to show the number of sigma bonds ($\sigma$) and pi bonds ($\pi$) present in a molecule of $\mathbf{X}$. Table 3.1

Use the bond energy values in Table 4.1 to calculate the enthalpy change, $\mathrm{\Delta }{H}_r$, for reaction 1. Table 4.1

$\mathrm{\Delta }{H}_r=\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{k}\mathrm{J}{\mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$

Reaction 1 reaches equilibrium at constant temperature and pressure. Deduce what effect increasing the pressure will have on the amount of ethanol in the new equilibrium mixture. Use Le Chatelier’s principle to explain your answer. effect of increasing pressure ..................................................................................................... explanation ............................................................................................................................... ...................................................................................................................................................

The mechanism for reaction 1 can be described in three steps. Steps 1 and 2 for reaction 1 are shown in Fig. 4.1. Describe the behaviour of ${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_4$ in step 1 in Fig. 4.1. Explain your answer.

Identify the species that behaves as an electrophile in step 2 in Fig. 4.1. Explain your answer.

Complete Fig. 4.2 to show the mechanism for step 3 of reaction 1. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate.

Describe how a catalyst affects a reaction. Explain your answer.

Use Fig. 4.1 and Fig. 4.2 to justify why ${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_4$ is described as a catalyst in reaction 1.

Propene also reacts with steam. A mixture of organic products is produced. Explain why propan-2-ol is produced in the higher yield.

Describe the covalent bonds present between the carbon atoms in an ethene molecule by completing Table 4.2. Table 4.2

Describe structural isomerism.

$\mathbf{A}$ and $\mathbf{B}$ are structural isomers with molecular formula ${\mathrm{C}}_5{\mathrm{H}}_{10}\mathrm{O}$. They are both straight-chained molecules with only one functional group. Table 5.1 describes observations when separate samples of $\mathbf{A}$ and $\mathbf{B}$ are added to different reagents. Table 5.1

Name the functional group present in both $\mathbf{A}$ and $\mathbf{B}$.

Draw the structures of $\mathbf{A}$ and $\mathbf{B}$ in the boxes.

$\mathbf{C}$ is a structural isomer of $\mathbf{A}$ and $\mathbf{B}$. $\mathbf{C}$ is straight chained and has two functional groups. $\mathbf{C}$ shows only one type of stereoisomerism. Table 5.2 describes observations when separate samples of $\mathbf{C}$ are added to different reagents. Table 5.2

Draw the structure of $\mathbf{C}$ in the box.

Name the type of stereoisomerism shown by molecules of $\mathbf{C}$.

$\mathbf{D}$ reacts in the presence of a sulfuric acid catalyst to form $\mathbf{E}$ and water. The structure of $\mathbf{E}$ is shown in Fig. 5.1. Name the functional group present in $\mathbf{E}$.

Identify the type of reaction that occurs when $\mathbf{D}$ reacts to form $\mathbf{E}$.

Draw the structure of $\mathbf{D}$ in the box.

The infrared spectrum of $\mathbf{E}$ is shown in Fig. 5.2. Table 5.3

Use Fig. 5.2 and Table 5.3 to predict two differences in the absorptions above $1500{\mathrm{c}\mathrm{m}}^{-1}$ of the infrared spectrum of $\mathbf{D}$ compared to $\mathbf{E}$. Explain your answer.