A Level Chemistry 9701 Paper 23, May/June 2025

Give the full electronic configuration of a fluorine atom.

Deduce the number of pairs of electrons in the second energy shell, $n=2$, of an oxygen atom.

Draw the shape of the highest energy orbital that contains electrons in an atom of calcium.

Write an equation to represent the first ionisation energy of sulfur.

Explain why the first ionisation energy of sulfur is less than the first ionisation energy of phosphorus.

Arrange the three species ${\text{F}}^{-}$, $\text{Ne}$ and ${\text{Na}}^{+}$ in order of increasing radius. Explain your answer. .................................. < .................................. < .................................. smallest radius largest radius

A Period 3 oxide produces a solution with a pH greater than 10 when it is added to water. State the formula of the oxide.

${\text{P}}_4{\text{O}}_{10}$ is added to an excess of aqueous $\text{NaOH}$. Write an equation to describe the reaction.

Table 2.1 shows the melting points of some oxides. Table 2.1

Identify the oxide from Table 2.1 that contains the element with the highest oxidation number.

A student suggests the following hypothesis. The melting point of an ionically bonded oxide is only determined by the charge on the cation. Use Table 2.1 to deduce if this hypothesis is true or false or if there is not enough information to make a conclusion. Explain your answer.

State why $\text{ZnO}$ is described as a Brønsted–Lowry base when it is added to ${\text{H}}_2{\text{SO}}_4(\text{aq})$.

${\text{Al}}_2{\text{O}}_3$ is a white amphoteric compound. State the formula of the aluminium-containing species produced when ${\text{Al}}_2{\text{O}}_3$ reacts with $\text{NaOH}(\text{aq})$.

State the formula of the aluminium-containing salt produced when ${\text{Al}}_2{\text{O}}_3$ reacts with ${\text{H}}_2{\text{SO}}_4(\text{aq})$.

Different hydrocarbon mixtures produced from fractional distillation of crude oil have different uses. State the compound that is heated with long-chain hydrocarbons to produce more useful smaller alkanes and alkenes.

Describe how photochemical smog is produced during the combustion of petrol in an internal combustion engine.

${\text{C}}_4{\text{H}}_8$ reacts with an excess of ${\text{H}}_2$ to produce ${\text{C}}_4{\text{H}}_{10}$. $$\text{reaction 1}{\text{C}}_4{\text{H}}_8+{\text{H}}_2\to {\text{C}}_4{\text{H}}_{10}$$ Name a catalyst for reaction 1.

Define activation energy, $E_{\text{A}}$.

The Boltzmann distribution for the reaction mixture in reaction 1 is shown in Fig. 3.1. Use the Boltzmann distribution to explain the effect of adding a catalyst on the rate of reaction. [Fig. 3.1]

Use Fig. 4.1 to find the average rate of change of concentration of $\text{HCl}(\text{aq})$ in this reaction between 0–100 seconds and between 400–500 seconds. Include units in your answers. 0–100 seconds .................................................. units ........................................... 400–500 seconds .............................................. units ...........................................

Use Fig. 4.1 to identify the limiting reagent. Explain your answer.

Explain why the rate of reaction changes with time.

The reaction between ${\text{Na}}_2{\text{S}}_2{\text{O}}_3(\text{aq})$ and $\text{HCl}(\text{aq})$ is repeated in a second experiment. In this second experiment, $25.0{\text{cm}}^3$ of $0.050\text{mol}{\text{dm}}^{-3}$ ${\text{Na}}_2{\text{S}}_2{\text{O}}_3(\text{aq})$ reacts with $0.0020\text{mol}$ of $\text{HCl}(\text{aq})$. Calculate the number of sulfur atoms produced. number of sulfur atoms produced = ..............................

Explain why the rate of reaction cannot be monitored accurately by measuring the volume of ${\text{SO}}_2(\text{g})$ produced in this reaction.

Fig. 4.2 shows a possible arrangement of outer-shell electrons in one ${\text{SO}}_2$ molecule. [Fig. 4.2] Use Fig. 4.2 to predict the shape and bond angle of a molecule of ${\text{SO}}_2$. shape ............................................. bond angle .......................°

Use Table 4.1 to predict the strength of the dipole moment of ${\text{SO}}_2$, if any, compared to that of ${\text{H}}_2\text{O}$. Explain your answer. Table 4.1

W is a colourless liquid. [Fig. 5.1] Deduce the empirical formula of W.

Two different reagents are each added to separate samples of W as shown in Table 5.1. Complete Table 5.1. Table 5.1

Fig. 5.2 shows two reactions of W to produce organic compounds Y and Z. [Fig. 5.2] Deduce the number of sigma ($\sigma$) bonds and pi ($\pi$) bonds present in Z. number of $\sigma$ bonds .................... number of $\pi$ bonds ....................

W reacts with ${\text{LiAlH}}_4$ to produce Y. Draw the structure of Y.

Identify the role of ${\text{LiAlH}}_4$ when it reacts with W.

Suggest the reagent and conditions required when W is converted into Z.

Fig. 5.3 shows the structure of Z. Fig. 5.4 is the infrared spectrum of Z. [Fig. 5.4] Identify the bond and functional group responsible for each of the absorptions labelled A, B, C and D in Fig. 5.4. A ........................................................................................................................................ B ........................................................................................................................................ C ........................................................................................................................................ D ........................................................................................................................................

Table 5.2

Z is used to produce addition polymer Q. Draw the repeat unit of polymer Q.

Poly(ethene) is an addition polymer made from ethene. Explain why ethene reacts with electrophiles but poly(ethene) does not.

$\text{HOCl}$ reacts with ${\text{CH}}_2={\text{CH}}_2$ to produce ${\text{HOCH}}_2{\text{CH}}_2\text{Cl}$ in an electrophilic addition reaction. Define addition reaction.

Describe how ${\text{Cl}}_2$ is used to produce $\text{HOCl}$.

State one use for $\text{HOCl}$.

Complete Fig. 6.1 to show the mechanism for the reaction between $\text{HOCl}$ and ${\text{CH}}_2={\text{CH}}_2$ to produce ${\text{HOCH}}_2{\text{CH}}_2\text{Cl}$. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. [Fig. 6.1]

${\text{HOCH}}_2{\text{CH}}_2\text{Cl}$ reacts in a two-step synthesis to produce ${\text{HOCH}}_2{\text{CH}}_2\text{COOH}$, as shown in Fig. 6.2. [Fig. 6.2] State the reagent and conditions for step 1.

Identify the type of reaction that occurs in step 2.

Complete the equation to show the reaction in step 2. ${\text{HOCH}}_2{\text{CH}}_2\text{CN}+$ .........................................................................................................