Oct/Nov 2022

Which sample contains the same number of the named species as the number of molecules present in 35.5 g of chlorine?

Atoms, molecules and stoichiometry

A student combines $25.0\,\text{cm}^3$ of $0.350\,\text{mol dm}^{-3}$ sodium hydroxide solution with $25.0\,\text{cm}^3$ of $0.350\,\text{mol dm}^{-3}$ hydrochloric acid. The temperature rises by $2.5\,\degree\text{C}$. No heat is transferred to the surroundings. The resulting mixture has a specific heat capacity of $4.2\,\text{J cm}^{-3}\,\text{K}^{-1}$. Determine the molar enthalpy change for the reaction?

Chemical energetics

When bacteria convert ammonium ions into nitrate ions, what is the change in the oxidation number of nitrogen?

Electrochemistry

During the reaction of sodium dichromate(VI), $\text{Na}_2\text{Cr}_2\text{O}_7$, with hydrogen peroxide, $\text{H}_2\text{O}_2$, $\text{Cr}^{3+}$ ions, water and oxygen are formed. What is the correctly balanced ionic equation for this reaction?

Electrochemistry

For which equilibrium reaction is the equilibrium position shifted to the right-hand side when the temperature is raised and the pressure is lowered?

Equilibria

Industrially, ethanol is made by adding ethene to steam. $\text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)} \rightleftharpoons \text{C}_2\text{H}_5\text{OH(g)}$ $K_p$ is equal to $1.8 \times 10^{-5}$, and the equilibrium partial pressures for the reactants are given below. Ethene: $4.8 \times 10^3\,\text{kPa}$ Steam: $2.8 \times 10^3\,\text{kPa}$ Which row is the correct one?

Equilibria

An excess of magnesium ribbon is introduced into dilute hydrochloric acid, and the amount of hydrogen gas produced is recorded as the reaction continues. The reaction is exothermic. The results are plotted on a graph showing total volume ($\text{cm}^3$) against time (s), with points P, Q and R marked. Which row explains how the rate of reaction changes between points P and Q and between points Q and R?

Reaction kinetics

Measurements are carried out in order to find the activation energy, $E_a$, of a reaction. The diagram illustrates $E_a$ on the Boltzmann distribution at temperature $T_1$. Further measurements are then taken at a higher temperature, $T_2$. Which diagram shows the correct Boltzmann distribution and $E_a$ at $T_2$?

Reaction kinetics

The electrical conductivities of two compounds, Y and Z, are listed below. For Y: the compound has good conductivity when in the liquid state; the mixture formed after adding the compound to water also has good conductivity. For Z: the compound does not conduct in the liquid state; the mixture formed after adding the compound to water has good conductivity. What are compounds Y and Z?

Chemical bonding

Which row gives the relative ionic radii of $\text{Na}^+$, $\text{Mg}^{2+}$ and $\text{S}^{2-}$?

The Periodic Table: chemical periodicity

The oxides BaO, CaO, MgO and SrO all form alkaline solutions when they are added to water. Which oxide gives the saturated solution with the greatest pH?

Equilibria

Mixture R contains one mole of $\text{C}_3\text{H}_6$ and one mole of $\text{C}_4\text{H}_6$. What is the smallest number of moles of oxygen molecules required for the complete combustion of mixture R?

Atoms, molecules and stoichiometry

Which row is the correct one?

Atomic structure

Which statement relating to Group 17 elements and compounds is correct?

Group 17

Chlorine gas is passed through $100\,\text{cm}^3$ of hot $4.0\,\text{mol dm}^{-3}$ sodium hydroxide until the reaction has finished. $6\text{NaOH(aq)} + x\text{Cl}_2\text{(aq)} \rightarrow y\text{NaCl(aq)} + z\text{NaClO}_3\text{(aq)} + 3\text{H}_2\text{O(l)}$ Which row is the correct one?

Atoms, molecules and stoichiometry

Which statement concerning ammonia or the ammonium ion is true?

Nitrogen and sulfur

Sulfur dioxide can undergo catalytic oxidation in the atmosphere using an oxide of nitrogen. Which reaction equation shows the catalyst being regenerated?

Reaction kinetics

Individual $1.0\,$g portions of $\text{Na}_2\text{O}$, $\text{MgO}$, $\text{Al}_2\text{O}_3$, $\text{SiO}_2$, $\text{NaCl}$, $\text{MgCl}_2$, $\text{Al}_2\text{Cl}_6$ and $\text{SiCl}_4$ are each placed in separate beakers containing water and then stirred. The number of beakers that contain a white solid is $Q$. Next, an excess of $\text{NaOH(aq)}$ is added to every beaker and the mixture is stirred. The number of beakers that now contain a white solid is $R$. Which row is the correct one?

Equilibria

Which two alcohols are isomers of one another?

Hydroxy compounds

In one molecule of 2,2,4,5-tetramethylhexan-3-ol, how many chiral carbon atoms are present?

An introduction to AS Level organic chemistry

Which two reagents react with each other in a redox reaction?

Electrochemistry

The structure of santonin is illustrated below. Santonin is first reacted with warm dilute $\text{H}_2\text{SO}_4$. The product from this reaction is then treated with cold dilute acidified $\text{KMnO}_4$. This gives a final product, $Q$. How many hydrogen atoms in each molecule of product $Q$ will react with sodium metal?

Chemical bonding

Which statement about the electrons in a carbon atom in its ground state is correct?

Atomic structure

Compound $R$ may be prepared from 1-bromopropane by first carrying out a nucleophilic substitution reaction and then an oxidation reaction. What is the identity of $R$?

Organic synthesis

Three colourless liquids with the following formulae are in separate unlabelled bottles: $\text{CH}_3\text{CH}_2\text{CO}_2\text{H}$, $\text{CH}_3\text{CH(OH)CO}_2\text{H}$, $\text{CH}_3\text{COCO}_2\text{H}$. Which two tests, done on separate portions of each liquid, would allow each liquid to be identified successfully?

Carbonyl compounds

An alcohol, $X$, and a dicarboxylic acid, $Y$, react to produce the double ester, $Z$. The diagram displays the structure of the ester. Which row concerning the reactants that form ester $Z$ is correct?

Carboxylic acids and derivatives

$W$ is treated with alkaline $\text{I}_2\text{(aq)}$, producing a yellow precipitate and $\text{CH}_3\text{CH}_2\text{CO}_2^-\,$ ions. Which row identifies $W$ and the yellow precipitate?

Atoms, molecules and stoichiometry

Ethanal reacts with hydrogen cyanide in the presence of $\text{KCN}$ to form a hydroxynitrile. What is the initial step in the mechanism for this reaction?

Chemical bonding

When working through this question, take into account both structural isomerism and stereoisomerism. How many isomeric compounds that have molecular formula $\text{C}_5\text{H}_6\text{O}_4$ include two $-\text{CO}_2\text{H}$ groups together with one $\text{C}=\text{C}$ double bond?

Chemical bonding

Compound $X$ undergoes reaction with ethanoic acid in the presence of an $\text{H}^+$ catalyst, forming the compound shown. What is the molecular formula of compound $X$?

Hydroxy compounds

2-bromopropane is reacted with hot ethanolic sodium hydroxide. Which substance is formed as the major product in this reaction?

Halogen compounds

Which compounds could be used to prepare $Y$ in one step?

Organic synthesis

The monomer buta-1,3-diene can also take part in addition polymerisation in more than one way. Two polymers that can be formed are known as cis-poly(buta-1,3-diene) and trans-poly(buta-1,3-diene). In these names, cis and trans keep their standard meanings. State the structure of the repeat unit in cis-poly(buta-1,3-diene).

Chemical bonding

For the element sulfur, which pair of ionisation energies has the greatest difference between them?

The Periodic Table: chemical periodicity

For compound Z, the mass spectrum shows the M and M+1 peaks with relative abundances in the ratio $13:1$. Which compound is Z?

Analytical techniques

How many $\sigma$ bonds are contained in one $\text{H-C} \equiv \text{C-C(CH}_3\text{)=CH(CH}_3\text{)}$ molecule?

Chemical bonding

Which molecule contains the same number of bonding electrons as lone-pair electrons?

Chemical bonding

The table compares the properties of four solids, each with a different type of bonding. Which row gives the correct description for a solid that has a giant covalent structure?

Chemical bonding

An s-block element carbonate is treated with excess hydrochloric acid. A sample with a mass of 0.833 g of the carbonate produces $200\,\text{cm}^3$ of gas, collected under room conditions. Which metal carbonate is it?

Atoms, molecules and stoichiometry

The enthalpy changes of formation, $\Delta H_f^\circ$, for both $\text{PCl}_3$ and $\text{PCl}_5$ are exothermic. $\text{PCl}_3$ reacts with chlorine. $\text{PCl}_3(l) + \text{Cl}_2(g) \rightarrow \text{PCl}_5(s) \quad \Delta H^\circ_{reaction} = -124\,\text{kJ mol}^{-1}$. Which two statements are correct?

Chemical energetics

What causes phosphorus to have a greater first ionisation energy than silicon?

The Periodic Table: chemical periodicity

The enthalpy change values for the reactions that may occur are shown below. W: $\text{NaOH(aq)} + \text{HCl(aq)} \rightarrow \text{NaCl(aq)} + \text{H}_2\text{O(l)}\quad \Delta H^\circ = -56\,\text{kJ mol}^{-1}$ X: $\text{NaCl(aq)} + \text{H}_2\text{O(l)} \rightarrow \text{NaOH(aq)} + \text{HCl(aq)}\quad \Delta H^\circ = +56\,\text{kJ mol}^{-1}$ Y: $2\text{HI(g)} \rightarrow \text{H}_2\text{(g)} + \text{I}_2\text{(g)}\quad \Delta H^\circ = +11\,\text{kJ mol}^{-1}$ Z: $\text{H}_2\text{(g)} + \text{I}_2\text{(g)} \rightarrow 2\text{HI(g)}\quad \Delta H^\circ = -11\,\text{kJ mol}^{-1}$ Which statement concerning the activation energies of these reactions is correct?

Chemical energetics

The Haber process operates with a nitrogen partial pressure of $50\,\text{kPa}$, a hydrogen partial pressure of $150\,\text{kPa}$, a temperature of $400^\circ\text{C}$ and an iron catalyst. $\text{N}_2\text{(g)} + 3\text{H}_2\text{(g)} \rightleftharpoons 2\text{NH}_3\text{(g)}$ If all the other conditions remain unchanged, which alteration will produce a higher activation energy?

Reaction kinetics

The compound $(\text{CH}_3)_3\text{NAICl}_3$ is described as having a simple molecular structure. Which statement about $(\text{CH}_3)_3\text{NAICl}_3$ is correct?

Chemical bonding

You should use VSEPR theory when answering this question. A dot-and-cross diagram of an ozone, $\text{O}_3$, molecule is given. What bond angle is predicted for this molecule?

Chemical bonding

All of the substances shown are in the gaseous state. Under the conditions given, which substance is most likely to exhibit ideal behaviour?

States of matter

Which graph shows how the pressure $p$ and volume $V$ of a sample of an ideal gas vary when the temperature is constant?

States of matter

Use the enthalpy changes in the tables that are relevant to help you answer this question. Which enthalpy change value can be worked out for the reaction below? $2\text{C(g)} + 6\text{H(g)} \rightarrow \text{C}_2\text{H}_6\text{(g)}$

Chemical energetics

Element X only reacts with oxygen when it is heated strongly. It also combines with chlorine to form a covalently bonded chloride. Which element could X be?

Chemical bonding

The table gives the melting points of the Period 3 elements sodium to aluminium: element: Na, Mg, Al; melting point/K: 371, 923, 932. Which factor accounts for the rise in melting points from sodium to aluminium?

Chemical bonding

The nitrates of beryllium, calcium, magnesium and strontium all break down in the same way on heating. If $2.00\,\text{g}$ of one of these anhydrous nitrates decomposes to give $1.32\,\text{g}$ of gas, which nitrate is it?

Atoms, molecules and stoichiometry

Sodium peroxide, $\text{Na}_2\text{O}_2$, is employed to take in carbon dioxide from the air and give out oxygen in enclosed settings such as space capsules and submarines. $2\text{Na}_2\text{O}_2 + 2\text{CO}_2 \rightarrow 2\text{Na}_2\text{CO}_3 + \text{O}_2$ What mass of sodium peroxide would be needed to remove $2.4\,\text{dm}^3$ of carbon dioxide from the atmosphere under room temperature and pressure conditions?

Atoms, molecules and stoichiometry

The diagram shows that each test tube W, X, Y and Z contains $25\,\text{cm}^3$ of a $0.1\,\text{mol dm}^{-3}$ salt solution. W: $\text{BaCl}_2\text{(aq)}$, X: $\text{MgCl}_2\text{(aq)}$, Y: $\text{BaCl}_2\text{(aq)}$, Z: $\text{MgCl}_2\text{(aq)}$. Then $25\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{NaOH(aq)}$ is poured into test tubes W and X, while test tubes Y and Z receive $25\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{H}_2\text{SO}_4\text{(aq)}$. For W and X, which test tube has the larger pH, and for Y and Z, which test tube produces the larger mass of precipitate?

Group 2

What oxidation state does the chlorine-containing species that kills bacteria in drinking water have?

Group 17

Compound Q is a white crystalline solid that dissolves readily in water. If concentrated sulfuric acid is added to a dry sample of Q, steamy white fumes are produced. When these fumes are bubbled through aqueous silver nitrate solution, a white precipitate is seen. This precipitate dissolves in dilute ammonia solution. What is compound Q?

Group 17

R is a solid substance. When hydrochloric acid is added, R fizzes. R also reacts with hot aqueous sodium hydroxide and releases a gas that turns red litmus blue. What is the formula of R?

Atoms, molecules and stoichiometry

Photochemical smog is a form of air pollution that forms in urban areas when sunlight acts on substances emitted by vehicle exhausts. Which combination of primary pollutants causes photochemical smog to form?

Nitrogen and sulfur

T is a Period 3 element. Its first ionisation energy is lower than that of the element with one fewer proton. The oxide of T does not react with water. Which element is T?

The Periodic Table: chemical periodicity

The structure of tartaric acid is illustrated. Which of the following statements about tartaric acid are correct?

An introduction to AS Level organic chemistry

A carboxylic acid, P, does not have any chain isomers. It reacts with an alcohol, Q, which has only one positional isomer. What ester could be produced in a reaction between P and Q?

Carboxylic acids and derivatives

Which pair contains a hydrocarbon that does not have a chiral centre?

Hydrocarbons

What major product is produced when compound R is warmed with excess HBr?

Halogen compounds

In which species are the numbers of protons, neutrons and electrons all not the same?

Atomic structure

cis-but-2-ene is treated with cold, dilute, acidified potassium manganate(VII) solution to form product X. cis-but-2-ene is treated with hot, concentrated, acidified potassium manganate(VII) solution to form product Y. Which row gives the correct description of the reactions of X and Y?

Electrochemistry

In which reaction will the major organic product have the smallest relative molecular mass?

Atoms, molecules and stoichiometry

When $\text{C}_4\text{H}_9\text{Cl}$ is treated with warm dilute aqueous sodium hydroxide solution. Which isomer of $\text{C}_4\text{H}_9\text{Cl}$ gives the most stable cation intermediate?

Halogen compounds

$1.0\,\text{mol}$ of an organic compound, J, needs $6.0\,\text{mol}$ of oxygen for complete combustion. When $1.0\,\text{mol}$ of J is treated with sodium, $0.50\,\text{mol}$ of a gas is formed, and this gas makes a ‘pop’ with a lighted splint. If J is reacted with an excess of hot acidified potassium manganate(VII), an organic product is obtained that forms an orange-red precipitate with 2,4-DNPH reagent. Which compound is J?

Hydroxy compounds

When you answer this question, take account of structural isomerism and stereoisomerism. In hot concentrated sulfuric acid, 3-methylhexan-3-ol reacts to produce a number of isomeric compounds with the molecular formula $\text{C}_7\text{H}_{14}$. How many isomeric compounds can be produced in this reaction?

Hydroxy compounds

The table presents a student’s predictions about how three compounds will react. Which rows contain the correct predictions?

An introduction to AS Level organic chemistry

Which mechanism is used to describe the reaction of aldehydes and ketones with HCN + NaCN?

Chemical bonding

Propyl propanoate may be made in three stages, with propanenitrile as the sole organic starting material. During step 1, the nitrile is changed into compound X. During step 2, compound X is changed into compound Y. During step 3, compound Y is reacted with additional compound X to produce propyl propanoate. $\text{CH}_3\text{CH}_2\text{CN} \rightarrow X \rightarrow Y \rightarrow \text{CH}_3\text{CH}_2\text{CO}_2\text{CH}_2\text{CH}_2\text{CH}_3$ Which reagents would be suitable for step 1 and step 2?

Organic synthesis

The ester $\text{CH}_3\text{CH}_2\text{CO}_2\text{CH}_3$ undergoes hydrolysis on boiling with aqueous sodium hydroxide. Which compound is among the products formed?

Carboxylic acids and derivatives

Compound V undergoes polymerisation to produce polymer W. A part of polymer W is shown. What is the correct name of compound V?

Chemical bonding

Both calcium oxide and magnesium sulfide react with acid. $\text{CaO}(\text{s}) + 2\text{H}^+(\text{aq}) \rightarrow \text{Ca}^{2+}(\text{aq}) + \text{H}_2\text{O}(\text{l})$ $\text{MgS}(\text{s}) + 2\text{H}^+(\text{aq}) \rightarrow \text{Mg}^{2+}(\text{aq}) + \text{H}_2\text{S}(\text{g})$ A sample of these two compounds, $X$, is reacted with exactly $0.125\,\text{mol}$ of dilute hydrochloric acid. The quantity of hydrogen sulfide produced is $0.0250\,\text{mol}$. What mass of calcium oxide was in mixture $X$?

Atoms, molecules and stoichiometry

A molecule of an organic compound, P, has three carbon atoms and gives a strong absorption at $1720\,\text{cm}^{-1}$ in its infrared spectrum. P is oxidised using excess hot acidified potassium dichromate(VI), giving the organic product Q. Q gives a strong absorption at $1700\,\text{cm}^{-1}$ and a strong, broad absorption centred at $2800\,\text{cm}^{-1}$ in its infrared spectrum. Identify P.

Chemical bonding

In dilute acid, two moles of $\text{VO}_2^+$ ions react with one mole of zinc atoms. The products contain $\text{Zn}^{2+}$ ions together with an ion, $Y$. Ion $Y$ includes vanadium. In the reaction, only zinc and vanadium undergo a change in oxidation state. Which ion is $Y$?

Electrochemistry

The compound potassium bismuthate(V), $\text{KBiO}_3$, is a strong oxidising agent. What does the (V) in potassium bismuthate(V) indicate?

Electrochemistry

At $20\,^{\circ}\text{C}$, hydrogen peroxide breaks down slowly to give water and oxygen. $2\text{H}_2\text{O}_2 \rightleftharpoons 2\text{H}_2\text{O} + \text{O}_2 \qquad \text{equilibrium constant} = K_c$ This reaction proceeds more quickly in the presence of a catalyst. Which statement is correct?

Equilibria

A dimer, $Q$, is solid and stable, but in solution it establishes a dynamic equilibrium. $Q(\text{aq}) \rightleftharpoons 2R(\text{aq})$ The starting concentration of a $Q$ solution is $0.50\,\text{mol dm}^{-3}$. Once equilibrium is reached, $[Q(\text{aq})]$ decreases to $0.25\,\text{mol dm}^{-3}$. The variation in $[Q(\text{aq})]$ and $[R(\text{aq})]$ with time is shown on graphs until equilibrium is attained. $K_c$ is then worked out. Which graph and $K_c$ value are correct?

Equilibria

The reaction pathway for the forward reaction in a reversible reaction is shown. Which statement is correct?

Chemical energetics

Which sample has the same number of the specified species as the number of molecules present in 35.5 g of chlorine?

Atoms, molecules and stoichiometry

A student combines $25.0\,\text{cm}^3$ of $0.350\,\text{mol dm}^{-3}$ sodium hydroxide solution with $25.0\,\text{cm}^3$ of $0.350\,\text{mol dm}^{-3}$ hydrochloric acid. The temperature rises by $2.5^\circ\text{C}$. No heat is transferred to the surroundings. The final mixture has a specific heat capacity of $4.2\,\text{J cm}^{-3}\text{ K}^{-1}$. Calculate the molar enthalpy change for the reaction.

Chemical energetics

Bacteria change ammonium ions into nitrate ions. By how many does the oxidation number of nitrogen alter?

Electrochemistry

When sodium dichromate(VI), $\text{Na}_2\text{Cr}_2\text{O}_7$, reacts with hydrogen peroxide, $\text{H}_2\text{O}_2$, the products are $\text{Cr}^{3+}$ ions, water and oxygen. What is the correctly balanced ionic equation for this reaction?

Electrochemistry

For which equilibrium reaction is the equilibrium position shifted to the right when the temperature is raised and the pressure is lowered?

Equilibria

Industrially, ethanol is made by allowing ethene to react with steam. $\text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)} \rightleftharpoons \text{C}_2\text{H}_5\text{OH(g)}$ The value of $K_p$ is $1.8 \times 10^{-5}$, and the equilibrium partial pressures of the reactants are given below. Ethene: $4.8 \times 10^3\,\text{kPa}$ Steam: $2.8 \times 10^3\,\text{kPa}$ Which row gives the correct answer?

Equilibria

An excess of magnesium ribbon is placed into dilute hydrochloric acid, and the amount of hydrogen gas produced is measured while the reaction continues. The reaction gives out heat. The results are shown. Which row describes the changes in the rate of reaction from P to Q and from Q to R?

Reaction kinetics

Measurements are carried out to find the activation energy, $E_a$, of a reaction. The diagram displays $E_a$ on the Boltzmann distribution at temperature $T_1$. The measurements are then repeated at a greater temperature, $T_2$. Which diagram correctly represents the Boltzmann distribution and $E_a$ at $T_2$?

Reaction kinetics

The electrical conductivities of two compounds, Y and Z, are given. Compound Y conducts electricity while in the liquid state, and it also conducts after being added to water. Compound Z does not conduct electricity in the liquid state, but it does conduct after being added to water. Identify compounds Y and Z.

Chemical bonding

Which row shows the comparative sizes of the ionic radii of $\text{Na}^+$, $\text{Mg}^{2+}$ and $\text{S}^{2-}$?

The Periodic Table: chemical periodicity

When BaO, CaO, MgO and SrO are each placed in water, they all form alkaline solutions. Which oxide gives the saturated solution with the greatest pH?

Equilibria

Mixture R contains one mole of $\text{C}_3\text{H}_6$ and one mole of $\text{C}_4\text{H}_6$. What is the smallest number of moles of oxygen molecules required to ensure complete combustion of mixture R?

Atoms, molecules and stoichiometry

Which row is the correct one?

The Periodic Table: chemical periodicity

Which of the following statements about Group 17 elements and compounds is correct?

Group 17

Chlorine is passed through $100\,\text{cm}^3$ of hot $4.0\,\text{mol dm}^{-3}$ sodium hydroxide until the reaction finishes. $6\text{NaOH(aq)} + x\text{Cl}_2\text{(aq)} \rightarrow y\text{NaCl(aq)} + z\text{NaClO}_3\text{(aq)} + 3\text{H}_2\text{O(l)}$ Which row gives the correct answer?

Atoms, molecules and stoichiometry

Which statement concerning ammonia or the ammonium ion is correct?

Nitrogen and sulfur

Sulfur dioxide can be catalytically oxidised by an oxide of nitrogen in the atmosphere. Which reaction shows the catalyst being reformed?

Reaction kinetics

Separate $1.0\,\text{g}$ portions of $\text{Na}_2\text{O}$, $\text{MgO}$, $\text{Al}_2\text{O}_3$, $\text{SiO}_2$, $\text{NaCl}$, $\text{MgCl}_2$, $\text{Al}_2\text{Cl}_6$ and $\text{SiCl}_4$ are each placed into different beakers that contain water and then stirred. The number of beakers that contain a white solid is $Q$. An excess of $\text{NaOH(aq)}$ is then introduced into each beaker and the mixtures are stirred again. The number of beakers that now contain a white solid is $R$. Which row is correct?

The Periodic Table: chemical periodicity

Which two alcohols are isomers of one another?

Atoms, molecules and stoichiometry

In one molecule of 2,2,4,5-tetramethylhexan-3-ol, how many chiral carbon atoms are present?

An introduction to AS Level organic chemistry

Which two reagents react with each other in a redox reaction?

Electrochemistry

The structure of santonin is displayed. Santonin is first reacted with warm dilute $\text{H}_2\text{SO}_4$. The substance formed from this reaction is then treated with cold dilute acidified $\text{KMnO}_4$. A final product, $Q$, is produced. How many hydrogen atoms in each molecule of product $Q$ will react with sodium metal?

Carboxylic acids and derivatives

Which statement about the electrons in a carbon atom in the ground state is correct?

Atomic structure

Compound $R$ may be produced from 1-bromopropane by means of a nucleophilic substitution reaction, followed by an oxidation reaction. What is the identity of $R$?

Organic synthesis

Three colourless liquids with the formulae shown here are placed in separate unlabelled bottles: $\text{CH}_3\text{CH}_2\text{CO}_2\text{H}$, $\text{CH}_3\text{CH(OH)CO}_2\text{H}$, $\text{CH}_3\text{COCO}_2\text{H}$. Which two tests, when done on separate samples of each liquid, would allow each liquid to be identified successfully?

Analytical techniques

An alcohol, $X$, reacts with a dicarboxylic acid, $Y$, to produce a double ester, $Z$. The diagram below shows the structure of the ester. Which row concerning the reactants used to make ester $Z$ is correct?

Carboxylic acids and derivatives

$W$ is reacted with alkaline $\text{I}_2\text{(aq)}$ to produce a yellow precipitate and $\text{CH}_3\text{CH}_2\text{CO}_2^-\,$ ions. Which row gives the identity of $W$ and the yellow precipitate?

Carbonyl compounds

When $\text{KCN}$ is present, ethanal reacts with hydrogen cyanide to give a hydroxynitrile. What occurs in the first step of the mechanism for this reaction?

Chemical bonding

When answering this question, you should take both structural isomerism and stereoisomerism into account. How many isomeric compounds with molecular formula $\text{C}_5\text{H}_6\text{O}_4$ have two $-\text{CO}_2\text{H}$ groups and a single $\text{C=C}$ double bond?

Chemical bonding

Compound $X$ reacts with ethanoic acid in the presence of an $\text{H}^+$ catalyst to form the compound shown. What molecular formula does compound $X$ have?

Hydroxy compounds

When 2-bromopropane is reacted with hot ethanolic sodium hydroxide, which substance is formed as the major product of this reaction?

Halogen compounds

In a single-step reaction, which compounds could be used to produce $Y$?

Organic synthesis

The monomer buta-1,3-diene is able to undergo addition polymerisation in more than one way. Two polymers that can be produced are known as cis-poly(buta-1,3-diene) and trans-poly(buta-1,3-diene). Here, cis and trans are used in their normal sense. What is the structure of the repeat unit of cis-poly(buta-1,3-diene)?

Chemical bonding

For sulfur, between which two ionisation energies is the gap the greatest?

Atomic structure

For a compound, Z, the mass spectrum shows that the relative abundances of the M and M+1 peaks are 13 : 1. What is compound Z?

Analytical techniques

How many $\sigma$ bonds are there in one $\text{H-C} \equiv \text{C-C(CH}_3) = \text{CH(CH}_3)$ molecule?

Chemical bonding

Which molecule contains the same number of bonding electrons as lone-pair electrons?

Chemical bonding

The table compares properties of four solids that are held together by different kinds of bonding. Which row correctly describes the properties of a solid with a giant covalent structure?

Chemical bonding

An s-block element carbonate is treated with an excess of hydrochloric acid. A mass of 0.833 g of the carbonate produces $200\,\text{cm}^3$ of gas when measured under room conditions. Which metal carbonate is this?

Atoms, molecules and stoichiometry

The enthalpy changes of formation, $\Delta H_f^\circ$, for both $\text{PCl}_3$ and $\text{PCl}_5$ are exothermic. $\text{PCl}_3$ undergoes reaction with chlorine. $\text{PCl}_3(\ell) + \text{Cl}_2(g) \rightarrow \text{PCl}_5(s) \qquad \Delta H_{reaction}^\circ = -124\,\text{kJ mol}^{-1}$. Which pair of statements is correct?

Chemical energetics