May/June 2018

A gas has a lower density than air and is soluble in water. Which diagram shows the correct way to collect this gas?

Solids, liquids and gases

If $1$ volume of gas $R$ combines with precisely $5$ volumes of oxygen, the only products are carbon dioxide and water. What is $R$?

The mole and the Avogadro constant

Two features of a gas, $G$, are stated below. $\bullet$ $G$ changes copper(II) oxide into a pink-brown solid. $\bullet$ The volume of $1.4\,\text{g}$ of $G$ is $1.2\,\text{dm}^3$ at room temperature and pressure. What is $G$?

The mole and the Avogadro constant

The relative formula masses of four compounds are provided below. A student has a $1.0\,\text{g}$ sample of each compound. Which sample has the greatest number of moles of oxygen atoms?

The mole and the Avogadro constant

The diagrams illustrate an electrolysis experiment that uses inert electrodes. What might liquid $Y$ be?

Electrolysis

Which of the following statements about ionic compounds is correct?

Ion and ionic bonds

The diagram illustrates apparatus that may be used to extract aluminium from its ore. What are $J$, $K$ and $L$?

Extraction of metals

The diagram illustrates the energy profile for a reaction. Which statements about this reaction are correct?

Exothermic and endothermic reactions

The diagram illustrates the fractionation of petroleum (crude oil). Which row indicates the correct use of the fraction?

Fuels

Which compound is present in petroleum (crude oil)?

Alkanes

A student made two conclusions about calcium carbonate. Conclusion 1: The reaction with dilute hydrochloric acid happens more quickly with powdered calcium carbonate than with large pieces of calcium carbonate. Conclusion 2: Grinding large pieces of calcium carbonate into powder increases the surface area. Which statement is correct?

Rate of reaction

Which mixture can have its components separated by adding water, stirring, and then filtering?

Separation and purification

A compound causes acidified potassium manganate(VII) to lose its colour. Which compound could it be?

Alkenes

Nitrogen combines with oxygen in an equilibrium reaction. $\text{N}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{NO}(g)$ \quad $\Delta H = +170\,\text{kJ mol}^{-1}$ At equilibrium for this reaction, which statement is correct?

Reversible reactions and equilibrium

A solution of W shows the following properties: • If it is added to solid ammonium chloride in excess, a gas is produced that changes damp red litmus paper to blue. • If it is added in excess to a solution of pH 3, the final solution has a pH of 13. What is W?

The characteristic properties of acids and bases

Pure lead(II) sulfate is made by combining two substances, X and Y. Once the reaction has finished, the mixture is filtered, and pure lead(II) sulfate is collected. Which row shows the best method for preparing pure lead(II) sulfate?

Preparation of salts

What are the mass percentages of nitrogen in ammonium nitrate, NH$_4$NO$_3$, and in calcium nitrate, Ca(NO$_3$)$_2$?

Relative masses of atoms and molecules

The diagram below illustrates three stages in the production of sulfuric acid: sulfur $\xrightarrow{\text{step P}}$ sulfur dioxide $\xrightarrow{\text{step Q}}$ sulfur trioxide $\xrightarrow{\text{step R}}$ sulfuric acid. At which of these steps is a catalyst used?

Rate of reaction

Which of the following statements about the elements in the Periodic Table is correct?

Arrangement of elements

The locations of four elements are marked on the outline of part of the Periodic Table. Which element is a solid non-metal at r.t.p.?

Arrangement of elements

Which of the following is not a characteristic of transition elements?

Transition elements

Brass belongs to the group of alloys. Which statement about brass is true?

Alloys and their properties

Trials were performed on an aqueous solution of an unidentified compound, $P$. The observations are shown in the table. Aqueous sodium hydroxide added: green precipitate, soluble in excess to give a green solution. Dilute nitric acid added, followed by aqueous barium nitrate: white precipitate. Dilute nitric acid added, followed by aqueous silver nitrate: no precipitate. Which ions are present in $P$?

Identification of ions and gases

Which of the following statements about the reactions of some metals and metal compounds is correct?

Reactivity series

Which metal is used to galvanise iron?

Corrosion of metals

Iron is extracted in the blast furnace from haematite ore. Which process occurs in the blast furnace?

Extraction of metals

Aluminium is a Group III element. It is obtained from its ore by electrolysis. From aluminium’s position in the Periodic Table, its aqueous ion is expected to be ...1.... . The way it is extracted shows that aluminium is ...2.... in the reactivity series. Which words complete gaps 1 and 2?

Atomic structure and the Periodic Table

Which pair of gases are both not acidic?

Oxides

Which term correctly names the process of converting seawater into water that is safe to drink?

Separation and purification

Which formula is that of an alkane?

Alkanes

Z is a compound which: - can be made, as the sole other product, when the alkane $\text{C}_8\text{H}_{18}$ is cracked so as to form butane - decolourises bromine water - contains a branched chain. What is the formula of Z?

Alkenes

A carboxylic acid with molecular formula $\text{C}_4\text{H}_8\text{O}_2$ reacts with an alcohol with molecular formula $\text{C}_3\text{H}_8\text{O}$ to produce an ester. What might the formula of the ester produced be?

Carboxylic acids

Several properties of compound J are shown below. - It reacts with potassium carbonate to give carbon dioxide. - It reacts with ethanol to form a sweet-smelling liquid. - It reacts with sodium hydroxide to form a salt. What could be a possible identity of J?

The characteristic properties of acids and bases

Which substance would diffuse at the fastest rate?

Diffusion

Which partial structure is used to depict nylon?

Polymers

The ion $Q^{2+}$ contains three full electron shells. Which element is $Q$?

Atomic structure and the Periodic Table

The diagrams illustrate how particles are arranged in three solids: $X$, $Y$ and $Z$. The three solids are krypton, potassium and sodium chloride. Which row gives the correct identification of $X$, $Y$ and $Z$?

Solids, liquids and gases

During the electrolysis of $\text{CuSO}_4\text{(aq)}$, what ionic equation represents the reaction occurring at the cathode?

Electrolysis

Ethane, $\text{C}_2\text{H}_6$, and ammonia, $\text{NH}_3$, are covalent compounds. Their dot-and-cross diagrams are shown. Which of the following statements are correct?

Simple molecules and covalent bonds

Which of the following statements is correct?

Elements, compounds and mixtures

A student intends to demonstrate that the rate of the reaction between calcium carbonate and dilute hydrochloric acid doubles for each $10\,^{\circ}\text{C}$ increase in temperature. The student’s method is to measure the volume of carbon dioxide produced. The student has a Bunsen burner and a gas syringe. What other essential apparatus does the student need to use?

Rate of reaction

If 1 volume of gas R reacts with exactly 5 volumes of oxygen, only carbon dioxide and water are produced. Which gas is R?

Alkanes

A compound has a relative molecular mass of $166$. Which molecular formula could this compound have?

Relative masses of atoms and molecules

A sample with a mass of $63\,\text{g}$ of potassium manganate(VII), $\text{KMnO}_4$, is required to completely oxidise $23\,\text{g}$ of ethanol, $\text{C}_2\text{H}_5\text{OH}$, in acidic conditions. How many moles of ethanol are capable of being completely oxidised by one mole of potassium manganate(VII) under these conditions?

The mole and the Avogadro constant

The diagrams illustrate an electrolysis experiment with inert electrodes. What might liquid Y be?

Electrolysis

Magnesium may be made by carrying out electrolysis on molten magnesium chloride, $\text{MgCl}_2$. What products are produced at the anode and at the cathode during the electrolysis of molten magnesium chloride?

Electrolysis

The diagram illustrates apparatus that can be used to obtain aluminium from its ore. What are J, K and L?

Extraction of metals

A reaction is exothermic. Which diagram shows the correct energy profile for the reaction and the correct enthalpy change?

Exothermic and endothermic reactions

What fraction of petroleum (crude oil) is employed as a fuel in aircraft engines?

Fuels

The photosynthesis equation is shown below. $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow 6\text{O}_2 + \text{C}_6\text{H}_{12}\text{O}_6$ Which of the following statements about photosynthesis is correct?

Exothermic and endothermic reactions

Compound X reacts with an acid to form sulfur dioxide gas. A portion of X is put into a flask and acid is then added. The sulfur dioxide given off is collected, and its volume is recorded at different times. The outcomes are shown on a graph. Which statement about this experiment is correct?

Rate of reaction

By adding water, stirring and then filtering, which mixture can be split into its component substances?

Separation and purification

Which reactions include oxidation and reduction?

Redox

Nitrogen undergoes reaction with oxygen in an equilibrium reaction. $\text{N}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{NO}(g) \quad \Delta H = +170\,\text{kJ mol}^{-1}$ At equilibrium for this reaction, which statement is correct?

Reversible reactions and equilibrium

Lead(II) oxide, $\text{PbO}$, reacts with dilute nitric acid, so it neutralises the acid. Lead(II) oxide also reacts with aqueous sodium hydroxide, so it neutralises the alkali. Which term best describes lead(II) oxide?

Oxides

Which two reagents are most appropriate for preparing copper(II) chloride in the laboratory?

Preparation of salts

These compounds can be used as nitrogenous fertilisers. Which compound has the smallest percentage by mass of nitrogen?

Relative masses of atoms and molecules

The diagram illustrates three stages in the production of sulfuric acid. sulfur $\xrightarrow{\text{step P}}$ sulfur dioxide $\xrightarrow{\text{step Q}}$ sulfur trioxide $\xrightarrow{\text{step R}}$ sulfuric acid At which stages is a catalyst employed?

Reversible reactions and equilibrium

Indium (proton number 49) belongs to Group III of the Periodic Table. Antimony (proton number 51) belongs to Group V of the Periodic Table. Which statement that compares indium with antimony is correct?

Arrangement of elements

The locations of four elements are indicated on the outline of part of the Periodic Table. Which element is a solid non-metal at r.t.p.?

Arrangement of elements

Three elements each have oxidation states of $+2$ and $+3$. Which section of the Periodic Table contains these elements?

Transition elements

Brass is an alloy. Which of the following statements about brass is correct?

Alloys and their properties

Which row shows the right tests for identifying both ammonia and sulfur dioxide?

Identification of ions and gases

Copper(II) oxide reacts with carbon on heating. $2\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_2$ Which of the following statements about this reaction is correct?

Redox

The diagram depicts a cell that may be used to obtain a metal from its oxide. Molten aluminium oxide, copper(II) oxide, lead(II) oxide and magnesium oxide are each electrolysed in separate cells. Every cell receives the same number of electrons. Which statement is correct?

Electrolysis

Iron is produced in the blast furnace from the ore haematite. What process occurs in the blast furnace?

Extraction of metals

Aircraft manufacture needs a metal that: 1. has a fairly low density 2. resists corrosion. Which of these requirements is met by aluminium?

Properties of metals

Which two gases in the pair are both not acidic?

The characteristic properties of acids and bases

Seawater is desalinated so that it becomes safe to drink. Which main substance does desalination remove?

Water

Which diagram represents a branched-chain isomer of butane?

Alkanes

A linear alkene, $\text{C}_4\text{H}_8$, reacts with bromine in an addition reaction. What could the structure of the product be?

Alkenes

The diagram illustrates the structure of oxalic acid. Which alcohol is oxidised to produce oxalic acid?

Carboxylic acids

Some characteristics of compound $J$ are given. • It reacts with potassium carbonate, forming carbon dioxide. • It reacts with ethanol, producing a sweet-smelling liquid. • It reacts with sodium hydroxide, forming a salt. What could be the identity of $J$?

Carboxylic acids

Two gases, ammonia and hydrogen chloride, are introduced into the apparatus shown at the same pressure. After some time, a white solid appears on the inner surface of the tube. Which statements account for the white solid forming in the position shown?

Diffusion

The diagram illustrates the structure of nylon. Which compounds could be used to make nylon?

Polymers

Cerium, Ce, has atomic number 58. One $\text{Ce}^{4+}$ ion contains 140 nucleons in its nucleus. How many protons, neutrons, and electrons are present in one $\text{Ce}^{4+}$ ion?

Atomic structure and the Periodic Table

The diagrams illustrate the particle arrangements in three solids: X, Y and Z. These three solids are krypton, potassium and sodium chloride. Which row gives the correct identification of X, Y and Z?

Solids, liquids and gases

Which of the following statements about solid calcium chloride is correct?

Ion and ionic bonds

Ethane, $\text{C}_2\text{H}_6$, and ammonia, $\text{NH}_3$, both are covalent compounds. Their dot-and-cross diagrams are displayed. Which statements are true?

Simple molecules and covalent bonds

Which statement correctly describes the structure or bonding in metals?

Metallic bonding

Select the gases to respond to the questions. argon carbon dioxide carbon monoxide ethane hydrogen methane neon ozone sulfur dioxide sulfur trioxide You may use each gas one time, more than once, or not use it at all.

Identification of ions and gases

The elements in Group VII of the Periodic Table are known as the halogens.

Group VII properties

Barium chloride dissolves in water, whereas barium sulfate is insoluble.

Preparation of salts

This question focuses on ethanol and ethanoic acid. The structural diagrams for ethanol and ethanoic acid are shown.

Alcohols

Silicon is classified as a non-metal in Group IV of the Periodic Table.

Giant covalent structures

Copper pyrites is an ore that contains copper compounds. Among the compounds present in the ore is $\text{CuFeS}_2$.

Extraction of metals

A scientist examines how iron reacts with steam in a closed system. A dynamic equilibrium mixture is formed. $3\text{Fe}(s) + 4\text{H}_2\text{O}(g) \rightleftharpoons \text{Fe}_3\text{O}_4(s) + 4\text{H}_2(g)$

Reversible reactions and equilibrium

The diagram shows the structure of methanesulfonic acid.

The characteristic properties of acids and bases

Methylpropane is a saturated hydrocarbon, and its structure is shown.

Alkanes

Use the gases in the list below to answer the questions. ammonia carbon dioxide chlorine butane hydrogen nitrogen oxygen propane sulfur dioxide You may use each gas once, more than once, or not at all. Which gas fits each description:

Solids, liquids and gases

The structure of Ester A is shown here.

Formulae, functional groups and terminology

Transition elements are found in the central section of the Periodic Table. Iron and copper are typical examples of transition elements.

Transition elements

Silver chloride, $\text{AgCl}$, is an insoluble salt whereas silver nitrate is a soluble salt.

Preparation of salts

Phosphorus belongs to Group V of the Periodic Table and is classified as a non-metal.

The mole and the Avogadro constant

Naphtha is one fraction separated from petroleum (crude oil).

Alkanes

The diagram presents part of the structure of a polyester.

Polymers

Sphalerite is an ore that contains zinc compounds. One compound present in the ore is $\text{ZnS}$.

Extraction of metals

A scientist studies the thermal decomposition of calcium carbonate in a closed vessel. A dynamic equilibrium mixture is formed. $\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g)$

Reversible reactions and equilibrium

The structure of sulfamic acid is displayed.

The characteristic properties of acids and bases

A student carries out a set of titrations to work out the percentage of ethanoic acid in a vinegar sample. Diagrams of some of the apparatus used by the student are shown.

Acid–base titrations

Solid L is a mixture made up of two compounds. These compounds have the same positive ion but different negative ions. The table lists the tests a student carries out on L. Fill in the table with the observations for tests (a) and (c), and write the conclusion for test (b). If any gases are produced, they should be named and identified using an appropriate test and observation.

Identification of ions and gases

A molecule is made up of four amino acid units joined in the same way as in a protein. After hydrolysis, the colourless solution obtained is placed as a spot on chromatography paper. The paper is then put into a suitable solvent. The diagram shows the completed chromatogram.

Chromatography

A student explores the reactivity order of four metals by putting samples of each metal into aqueous solutions of their nitrates.

Reactivity series

With a catalyst present, hydrogen peroxide, $\text{H}_2\text{O}_2$, breaks down into water and oxygen. A student compares the rate of this decomposition at two different temperatures.

Rate of reaction

Mixtures may be separated by different methods, chosen according to the physical properties of the components. A student is given two mixtures.

Separation and purification

A student carries out an investigation into two fuels, hexane and octane. The student uses the apparatus shown to burn the fuels. In each experiment, a fixed volume of water is heated for five minutes. The diagrams display sections of the thermometer stem showing the starting and ending temperatures.

Exothermic and endothermic reactions

A chemist intends to run an experiment to determine the acid concentration in lemon juice. The preparation of the solution and the titration method are outlined.

Acid–base titrations

When calcium carbonate reacts with dilute hydrochloric acid, carbon dioxide gas is produced.

Rate of reaction

A pair of solids, L and M, are combined. L dissolves in water, whereas M does not dissolve in water.

Identification of ions and gases

Ammonia is made when nitrogen reacts with hydrogen in the presence of a catalyst.

Reversible reactions and equilibrium

X is a colourless solution containing an oxidising agent. Y is a colourless solution containing a reducing agent. Z is a metal that lies between iron and calcium in the reactivity series.

Reactivity series

A student prepares an aqueous solution of potassium nitrate. She adds dilute nitric acid to an aqueous solution of a salt. State a salt that she could use.

Separation and purification

A scientist has to work out which metal ion is present in a metal carbonate, $MCO_3$. The $MCO_3$ is heated in a crucible, and it decomposes to produce $MO$ and $CO_2$.

The mole and the Avogadro constant