May/June 2022

A scientist has to pour approximately $100\,\text{cm}^3$ of water into each of 50 large beakers. The scientist wants to complete the filling as quickly as possible. Which method should be used?

Experimental design

Which dot-and-cross diagram shows carbon dioxide? Only electrons in the outer shell are shown.

Simple molecules and covalent bonds

Two statements on the structure and properties of metals are provided. statement 1 Metals are malleable and have high melting points. statement 2 Metals contain mobile electrons in their structure. Which statement is correct?

Metallic bonding

How many distinct elements are found in ammonium nitrate?

Elements, compounds and mixtures

Aqueous calcium hydroxide is an alkali. It is neutralised by dilute nitric acid, forming calcium nitrate and water. State the ionic equation for this reaction?

The characteristic properties of acids and bases

The relative molecular mass, $M_r$, of liquid Z is 60. Z is made up of 40.0% carbon, 6.70% hydrogen and 53.3% oxygen. Which row gives the correct empirical formula and molecular formula of Z?

Formulae

What mass, in tonnes, of aluminium oxide, $\text{Al}_2\text{O}_3$, is needed to make 27 tonnes of aluminium?

Relative masses of atoms and molecules

Inert electrodes are used to electrolyse lead(II) bromide. Which statement is correct?

Electrolysis

Compound X is sodium iodide, $\text{NaI}$. Compound Y is methyl methanoate, $\text{HCO}_2\text{CH}_3$. Under room temperature and pressure, ........1........ solid. In aqueous solution, ........2........ electricity. Which words complete gaps 1 and 2 correctly?

Ion and ionic bonds

For the forward direction of a reversible reaction, the enthalpy change of reaction, $\Delta H$, is $-50\,\text{kJ mol}^{-1}$ and the activation energy, $E_a$, is $+60\,\text{kJ mol}^{-1}$. What is the activation energy of the reverse reaction?

Reversible reactions and equilibrium

The diagram illustrates a titration experiment. Which row correctly describes the reaction taking place in the conical flask?

Acid–base titrations

The table lists four mixtures, and each mixture contains two substances. The two substances must be separated and collected. Which row is correct?

Separation and purification

Sulfur dioxide combines with oxygen in the air. $2\text{SO}_2(\text{g}) + \text{O}_2(\text{g}) \rightleftharpoons 2\text{SO}_3(\text{g}) \quad \Delta H = -196\,\text{kJ mol}^{-1}$ In the absence of a catalyst, the reaction rate is very low. Which statement accounts for this?

Rate of reaction

Which of the following statements is correct?

Elements, compounds and mixtures

Nitrogen dioxide, $\text{NO}_2$, is a dark brown gas which breaks down as shown in the equation. $2\text{NO}_2(\text{g}) \rightleftharpoons 2\text{NO}(\text{g}) + \text{O}_2(\text{g})$ dark brown  colourless A glass flask contains a mixture of these three gases. The mixture appears pale brown. Additional oxygen is pushed into the flask. Which colour change is observed in the mixture?

Reversible reactions and equilibrium

Concentrated hydrochloric acid is oxidised by manganese(IV) oxide, $\text{MnO}_2$. Which two substances are produced in this reaction?

Redox

The table shows details about four redox reactions. Which row correctly states what is oxidised and the evidence that this is oxidation?

Redox

Which of the following statements about acids and bases is correct?

The characteristic properties of acids and bases

The following types of chemical reaction are shown. Which of these reaction types take place in a blast furnace during the extraction of iron?

Extraction of metals

Which method should be used to obtain a pure sample of potassium chloride?

Preparation of salts

A pure sample of lead sulfate is prepared by mixing two aqueous salt solutions. The precipitated lead sulfate is then removed from the reaction mixture. Which solutions are used, and how is the lead sulfate separated?

Preparation of salts

Which of the following statements is correct?

Elements, compounds and mixtures

Separate tests are carried out on two samples of a colourless solution using aqueous sodium hydroxide, $\text{NaOH(aq)}$, and aqueous ammonia, $\text{NH}_3\text{(aq)}$, and the observations are noted. • A white precipitate appears when two drops of $\text{NaOH(aq)}$ are added. In excess $\text{NaOH(aq)}$, this precipitate dissolves. • A white precipitate appears when two drops of $\text{NH}_3\text{(aq)}$ are added. In excess $\text{NH}_3\text{(aq)}$, this precipitate dissolves. What conclusion can be drawn from these observations?

Identification of ions and gases

Element $Y$ lies in Period 3 of the Periodic Table. It makes a chloride which is liquid at room temperature. Which row gives the correct group number and the nature of the oxide of element $Y$?

Arrangement of elements

What gases are used inside light bulbs?

Solids, liquids and gases

The carbonates of metals $W$, $X$ and $Y$ are heated, and the outcomes are shown. These test results can be used to make statements about $W$, $X$ and $Y$. Which of the statements are correct?

Group I properties

The diagram illustrates an experiment used to find the percentage of oxygen in air. Which diagram shows the correct water level once the candle has gone out?

Air quality and climate

Two statements are provided. statement 1: The mass percentage of carbon is higher in methane than in butane. statement 2: Butane is one of two isomers that have the molecular formula $\text{C}_4\text{H}_{10}$. Which of these statements are correct?

Formulae

Each of the compounds listed below is completely combusted, with one mole of each used. $\text{C}_5\text{H}_{12}\text{O}$, $\text{C}_6\text{H}_{12}$, $\text{C}_6\text{H}_{14}$, $\text{C}_6\text{H}_{14}\text{O}$ How many of these compounds require exactly nine moles of oxygen for complete combustion?

The mole and the Avogadro constant

The reactants and products for two reactions are shown. reaction 1: $\text{C}_3\text{H}_6 + \text{H}_2\text{O} \rightarrow X$ reaction 2: $X + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}$ Which row gives the correct description of these two reactions?

Alkenes

Which of the following statements about carboxylic acids is correct?

Carboxylic acids

The structure of an ester is displayed. What is this ester called?

Naming organic compounds

Poly(ethene) is produced by .....1..... polymerisation of ethene. Nylon and $\text{Terylene}$ are both made by .....2..... polymerisation. Proteins have the same .....3..... linkage as nylon. Fats have the same .....4..... linkage as $\text{Terylene}$. When proteins are hydrolysed, they produce .....5..... . Which words complete gaps 1-5 correctly?

Polymers

Which row gives the correct description of how the particles change when a substance freezes?

Solids, liquids and gases

The repeat unit of a polymer is shown. Which monomer could be used to make this polymer?

Polymers

Ethylamine gas, $\text{C}_2\text{H}_5\text{NH}_2$, reacts with hydrogen chloride gas, $\text{HCl}$, to produce a white solid called ethylamine hydrochloride. In which part of the tube would a ring of solid white ethylamine hydrochloride appear?

Diffusion

The two particles are shown by the symbols $^{54}_{26}\text{Fe}^{2+}$ and $^{59}_{27}\text{Co}^{3+}$. Which statement concerning these particles is correct?

Atomic structure and the Periodic Table

The two isotopes of chlorine are $^{35}\text{Cl}$ and $^{37}\text{Cl}$. By using these isotopes together with $^{12}\text{C}$ and $^1\text{H}$, how many distinct relative molecular masses can the compound with molecular formula $\text{C}_2\text{H}_3\text{Cl}_3$ have?

Isotopes

Which statement about these substances, at room temperature and pressure, is correct?

Solids, liquids and gases

A sample of magnesium is added to dilute hydrochloric acid. The mixture is then evaporated, and a solid residue of magnesium chloride is left behind. Which statement is correct?

Preparation of salts

A student carries out an investigation into the rate of reaction between calcium carbonate and hydrochloric acid. The gas volume in the syringe is noted after 1 minute. The experiment is repeated using hydrochloric acid at different concentrations. Which further pieces of apparatus are needed for the investigation?

Rate of reaction

The dot-and-cross diagram shows one molecule of tetrafluorosilane, $\text{SiF}_4$. Only the electrons in the outer shell are included. Which statement is correct?

Simple molecules and covalent bonds

The table gives two properties linked to metals. Which row gives the correct reason for the property stated?

Properties of metals

Aqueous silver nitrate, $\text{AgNO}_3$, reacts with aqueous potassium chromate(VI), $\text{K}_2\text{CrO}_4$, to form a yellow precipitate. What is the ionic equation for this reaction?

Identification of ions and gases

For anhydrous sodium carbonate, what is the relative formula mass?

Relative masses of atoms and molecules

Which has the largest mass of solute?

Elements, compounds and mixtures

What mass of aluminium oxide, $\text{Al}_2\text{O}_3$, is needed to make 27 tonnes of aluminium?

The mole and the Avogadro constant

Dilute sulfuric acid undergoes electrolysis. Hydrogen gas and oxygen gas are formed. Which row shows the correct description of what occurs?

Electrolysis

Aluminium may be extracted by electrolysing aluminium oxide dissolved in molten cryolite. Which reactions occur during this electrolysis?

Electrolysis

Among the reactions shown, which one is exothermic?

Exothermic and endothermic reactions

State the balanced equation and enthalpy change, $\Delta H$, for the complete combustion of butanol, $\text{C}_4\text{H}_9\text{OH}$.

Exothermic and endothermic reactions

Which of the following statements is correct?

Elements, compounds and mixtures

Bromate, bromide and hydrogen ions react in the equation shown. $\text{BrO}_3^-(aq) + 5\text{Br}^-(aq) + 6\text{H}^+(aq) \rightarrow 3\text{Br}_2(aq) + 3\text{H}_2\text{O}(l)$. A piece of apparatus for finding out how the rate of this reaction changes with time is suggested. Which apparatus is suitable to measure the rate of this reaction?

Rate of reaction

$25\,\text{cm}^3$ of $1.0\,\text{mol dm}^{-3}$ hydrochloric acid reacts with $10\,\text{g}$ of a solid to form a gas. The solid is in excess. The graph labelled first experiment shows how the volume of gas changes with time. Graphs P and Q show the volume of gas produced when the conditions are different. Which changes in conditions produce graphs P and Q, assuming that every other condition stays the same?

Rate of reaction

Nitrogen dioxide, $\text{NO}_2$, is a dark brown gas that breaks down according to the equation $2\text{NO}_2(g) \rightleftharpoons 2\text{NO}(g) + \text{O}_2(g)$. The diagram shows a glass flask holding a mixture of these three gases. The mixture is pale brown. More oxygen is pushed into the flask. Which colour change is observed in the mixture?

Reversible reactions and equilibrium

What observation is made during an oxidation process?

Redox

An excess of aqueous iodide ions is added to acidified aqueous potassium manganate(VII). Which row is correct?

Redox

When ammonia gas dissolves in water, a reversible reaction occurs. $\text{NH}_3(\text{g}) + \text{H}_2\text{O}(\text{l}) \rightleftharpoons \text{NH}_4^+(\text{aq}) + \text{OH}^-(\text{aq})$ Which statements are correct?

The characteristic properties of acids and bases

A separate reaction is carried out for each of three dilute acid solutions, all having a concentration of $0.01\,\text{mol dm}^{-3}$, with excess calcium carbonate, and the reaction is allowed to continue until no more reaction occurs. The same volume of acid is taken in every case. The carbon dioxide given off is collected, and its volume is recorded. Every measurement is made at room temperature and pressure. The results are: Acid 1: $\text{pH} = 2.0$, volume of carbon dioxide produced $= 20\,\text{cm}^3$ Acid 2: $\text{pH} = 1.7$, volume of carbon dioxide produced $= 40\,\text{cm}^3$ Acid 3: $\text{pH} = 3.4$, volume of carbon dioxide produced $= 20\,\text{cm}^3$ What are the possible identities of the acids?

The characteristic properties of acids and bases

The stages for preparing a pure sample of sodium nitrate are given below. 1. Titrate until the end-point is reached using dilute nitric acid. 2. Heat to evaporate water and make the solution more concentrated. 3. Wash out the conical flask. 4. Put in indicator. 5. Use a pipette to transfer a measured volume of aqueous sodium hydroxide into a conical flask. 6. Allow to cool, then filter off the crystals. 7. Carry out the procedure again with the same volumes of aqueous sodium hydroxide and dilute nitric acid, but without indicator. Which sequence of steps is correct?

Acid–base titrations

A colourless solid does not dissolve in water. Which cations and anions might be present in this compound?

Identification of ions and gases

The flow chart outlines how ammonium sulfate is prepared. What are elements 1-4?

Preparation of salts

Several reactions of an aqueous solution of compound $X$ are observed. On adding a few drops of aqueous sodium hydroxide, a white precipitate forms. When dilute nitric acid is then added and the mixture is warmed, a gas is produced. This gas decolourises acidified potassium manganate(VII). If dilute nitric acid and aqueous barium nitrate are added, there is no visible change. What can be deduced about the identity of $X$?

Identification of ions and gases

Which row correctly indicates the possible uses of sulfur dioxide and sulfuric acid?

The characteristic properties of acids and bases

Selenium is in Group VI and gallium is in Group III. What prediction can be drawn from this information?

Arrangement of elements

Which statement concerning some metals and their compounds is correct?

Transition elements

The diagram illustrates an experiment used to find the percentage of oxygen in air. Which diagram shows the correct water level after the candle has stopped burning?

Solids, liquids and gases

When bromine reacts with a hydrocarbon X, just one product is produced. Which compound is X?

Alkenes

A reaction sequence for making propanol from the naphtha fraction of petroleum (crude oil) is illustrated. What are processes X and Y?

Alcohols

The structural formulas of four alcohols are displayed. Which statement is correct?

Alcohols

Which compounds are shown by the molecular formula $\text{C}_3\text{H}_6\text{O}_2$?

Formulae, functional groups and terminology

An organic compound has the empirical formula $\text{CH}_2\text{O}$. Which row gives a name and structural formula that could be correct for this compound?

Naming organic compounds

Which of the following statements is correct?

Elements, compounds and mixtures

Which combination of changes in the conditions causes the volume of a gas to increase?

Solids, liquids and gases

A polymer’s repeat unit is shown. Which monomer would form this polymer?

Polymers

When ethylamine gas, $\text{C}_2\text{H}_5\text{NH}_2$, reacts with hydrogen chloride gas, $\text{HCl}$, a white solid called ethylamine hydrochloride is produced. In the tube, at which point would a ring of solid white ethylamine hydrochloride appear?

Diffusion

Element $X$ may be shown by the symbol $^{14}_{6}X$. Which of the following statements about one atom of element $X$ are correct?

Atomic structure and the Periodic Table

The chlorine isotopes $^{35}\text{Cl}$ and $^{37}\text{Cl}$ are given. If these isotopes are combined with $^{12}\text{C}$ and $^{1}\text{H}$, how many distinct relative molecular masses can the compound with molecular formula $\text{C}_2\text{H}_3\text{Cl}_3$ have?

Isotopes

Which row is the correct one?

Elements, compounds and mixtures

Which statement concerning ionic compounds is correct?

Ion and ionic bonds

Pick one compound from the list below to answer the questions. NH$_4$Cl BaSO$_4$ KI K$_2$SO$_3$ Mg(NO$_3$)$_2$ NaOCOCH$_3$ Na$_2$CO$_3$ Na$_3$PO$_4$ ZnSO$_4$ Any compound may be used once, more than once, or not used at all. State which compound:

Identification of ions and gases

The table presents some data about elements in Group V.

Arrangement of elements

The diagram represents several reactions of butanol. At the centre is butanol, $\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH}$. When complete combustion occurs, gas A and liquid B are formed. When combustion is incomplete, liquid B and gas C are formed. Oxidation with acidified potassium manganate(VII) gives organic liquid D. Heating with ethanoic acid produces liquid B and organic liquid E.

Alcohols

The table gives information about several particles.

Ion and ionic bonds

Iron undergoes reaction with steam and with dilute sulfuric acid.

Reversible reactions and equilibrium

Carbon monoxide and nitrogen monoxide are pollutant gases produced in a car engine.

Rate of reaction

Aluminium belongs to Group III in the Periodic Table.

Extraction of metals

Alkenes form a homologous series of unsaturated hydrocarbons.

Alkenes

Ammonia, NH$_3$, is used in the manufacture of nitrogenous fertilisers.

Fertilisers

Use the compounds listed below to answer the questions. AgCl Ba(NO$_3$)$_2$ KI KMnO$_4$ K$_2$SO$_3$ Mg(NO$_3$)$_2$ Na$_2$CO$_3$ Na$_3$N NH$_4$Cl ZnSO$_4$ Each compound can be chosen once, more than once, or not used. State which compound:

Identification of ions and gases

Nitric acid, HNO$_3$, is used in the manufacture of fertilisers.

Fertilisers

The table presents some data about elements in Group VI.

Arrangement of elements

The diagram depicts several reactions of butanoic acid. It shows a central butanoic acid structure, reaction with magnesium giving gas A and salt B, reaction with magnesium carbonate giving salt B, gas C and liquid D, and heating with ethanol giving liquid D and organic liquid E.

The characteristic properties of acids and bases

The table presents information about a few particles.

Ion and ionic bonds

Ethanol is produced by reacting ethene with steam. The conditions are $300\,^{\circ}\text{C}$, high pressure and a phosphoric acid catalyst.

Reversible reactions and equilibrium

A sample of an alloy made up of aluminium and copper is placed in hot dilute sulfuric acid. The dilute sulfuric acid reacts only with the aluminium. Hydrogen and aqueous aluminium sulfate are formed in the reaction.

Preparation of salts

Carbon dioxide and sulfur dioxide are pollutants released at power stations that burn fossil fuels such as coal.

Rate of reaction

Zinc is a metallic element.

Metallic bonding

Alkanes form a homologous series of saturated hydrocarbons.

Alkanes

The student pours $4.0\text{ cm}^3$ of aqueous potassium manganate(VII) from the burette into apparatus A.

Rate of reaction

A student is given a mixture of solid ionic compounds. They put the mixture into a beaker of water and stir the contents. The beaker now contains a colourless solution and an insoluble black solid.

Identification of ions and gases

A student is given three colourless organic liquids, W, X and Y. Of these, one is an alkene, one is an alcohol and one is a carboxylic acid, but the student does not know the identity of each liquid.

Formulae, functional groups and terminology

A student finds the concentration of aqueous sodium hydroxide, $\text{NaOH(aq)}$, by titrating it with aqueous citric acid, $\text{C}_6\text{H}_8\text{O}_7\text{(aq)}$.

Acid–base titrations

The student pours $25\text{ cm}^3$ of $1.0\text{ mol dm}^{-3}$ hydrochloric acid into a glass beaker, takes the temperature, then adds $30\text{ cm}^3$ of aqueous potassium hydroxide in excess and notes the highest temperature reached.

Exothermic and endothermic reactions

A student works out the concentration of aqueous potassium manganate(VII), $\text{KMnO}_4$, by carrying out a titration with ethanedioic acid solution, $\text{H}_2\text{C}_2\text{O}_4$. The reaction may be represented by the equation shown below. $2\text{KMnO}_4 + 5\text{H}_2\text{C}_2\text{O}_4 + 6\text{H}^+ \rightarrow 2\text{Mn}^{2+} + 10\text{CO}_2 + 8\text{H}_2\text{O} + 2\text{K}^+$

Acid–base titrations

One cation is present in the solution together with two different anions.

Identification of ions and gases

A student is recording how the temperature changes in the reaction of $\text{HCl\,(aq)}$ with aqueous sodium hydroxide, $\text{NaOH\,(aq)}$. $\text{NaOH\,(aq)} + \text{HCl\,(aq)} \rightarrow \text{NaCl\,(aq)} + \text{H}_2\text{O\,(l)}$

Experimental design

This apparatus is employed to electrolyse dilute sulfuric acid, yielding hydrogen gas and oxygen gas.

Electrolysis

Using the apparatus shown, a student investigates how quickly excess copper(II) carbonate reacts with dilute sulfuric acid. $\text{CuCO}_3\text{(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{CuSO}_4\text{(aq)} + \text{CO}_2\text{(g)} + \text{H}_2\text{O\,(l)}$

Rate of reaction