Oct/Nov 2018

A student carries out a titration by delivering aqueous sodium hydroxide from a burette into dilute hydrochloric acid in a conical flask. When the titration ends, the conical flask is emptied. What should be done before beginning the next titration?

Acid–base titrations

What are the relative formula masses for one mole of solid magnesium and one mole of chlorine gas?

Relative masses of atoms and molecules

In a complete combustion reaction, a hydrocarbon forms only carbon dioxide, $\text{CO}_2$, and water, $\text{H}_2\text{O}$. $\text{C}_5\text{H}_{12}(l) + 8\text{O}_2(g) \rightarrow 5\text{CO}_2(g) + 6\text{H}_2\text{O}(g)$ If $0.1\,\text{mol}$ of the hydrocarbon $\text{C}_5\text{H}_{12}$ undergoes complete combustion, what volume of carbon dioxide is produced at room temperature and pressure?

The mole and the Avogadro constant

What is seen during the electrolysis of aqueous copper(II) sulfate with carbon electrodes?

Electrolysis

Electrolysis is used to coat a metal statue with silver. The statue acts as an electrode in a suitable electrolyte. Which row is correct?

Electrolysis

Which of the following statements about endothermic reactions are correct? 1. Energy is taken in from the surroundings. 2. Energy is given out to the surroundings. 3. The temperature of the reaction mixture decreases. 4. The temperature of the reaction mixture increases.

Exothermic and endothermic reactions

The equation shows the reaction of the two gases $\text{X}_2$ and $\text{Y}_2$ to produce the compound XY. $\text{X}_2(g) + \text{Y}_2(g) \rightarrow 2\text{XY}(g)$ The energy profile diagram for this reaction is given. Which of the following statements about this reaction is correct?

Exothermic and endothermic reactions

The equation represents the reaction used to make ammonia. $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ Which change will lower the activation energy of this reaction?

Rate of reaction

On adding bismuth(III) chloride, $\text{BiCl}_3$, to water, a reaction takes place and a white precipitate of BiOCl is produced. $\text{BiCl}_3(aq) + \text{H}_2\text{O}(l) \rightleftharpoons \text{BiOCl}(s) + 2\text{HCl}(aq)$ Which of these changes would increase the mass of white precipitate produced? 1. adding extra water 2. adding aqueous sodium hydroxide 3. adding dilute hydrochloric acid

Reversible reactions and equilibrium

When calcium carbonate reacts with dilute hydrochloric acid, carbon dioxide is formed. The carbon dioxide is gathered with the apparatus shown. The reaction is carried out four times. In each reaction, $25\,\text{g}$ of calcium carbonate and an excess of hydrochloric acid are used. Which reaction mixture fills the gas syringe with carbon dioxide in the shortest time?

Rate of reaction

Numerous reactions involve oxidation and reduction. Which statement is correct?

Redox

The outcome of a paper chromatography experiment is shown below. X is an aqueous solution of a salt of a Group I element. Y is an aqueous solution of a salt of a transition element. Which row is correct?

Chromatography

Three different combinations of a solution and a solid are prepared, as shown in the table. The mixtures are heated. In which mixtures is gas produced?

The characteristic properties of acids and bases

Insoluble salts are made by mixing aqueous solutions of soluble salts, causing a precipitate to appear. Which pairs of aqueous solutions produce a precipitate? 1. barium chloride and nitric acid 2. barium chloride and sulfuric acid 3. barium nitrate and nitric acid 4. barium nitrate and sulfuric acid

Identification of ions and gases

The diagram illustrates the principal stages in producing an ammonia-based fertiliser. What is occurring in the process marked X?

Fertilisers

What is one application of sulfuric acid?

The characteristic properties of acids and bases

Which property exhibits an increasing pattern in the elements, moving from Group I to Group VII, across a period of the Periodic Table?

Arrangement of elements

Lithium has a melting point of $181\,^{\circ}\text{C}$, whereas sodium melts at $98\,^{\circ}\text{C}$. Which statement accounts for the fact that lithium has a higher melting point than sodium?

Metallic bonding

From the place of vanadium, chromium and cobalt in the Periodic Table, what properties would you predict for these elements?

Transition elements

The diagram illustrates the arrangement in an alloy. Which statement about alloys is correct?

Alloys and their properties

The sequence below places metal X in the reactivity series of metals: Na Al Fe X Cu Ag. Which procedures could be used to extract metal X?

Extraction of metals

An earlier industrial method for extracting aluminium used large amounts of sodium to change aluminium ions into aluminium atoms. The present aluminium extraction process makes use of electrolysis. Which statements are correct?

Extraction of metals

A colourless solution is obtained when a substance is mixed with water. If aqueous silver nitrate is then added in the presence of dilute nitric acid, a yellow precipitate appears. What is the likely identity of the substance?

Identification of ions and gases

Which element is always found in steel?

Alloys and their properties

Aluminium is used to make saucepans because it appears to be unreactive. Which property of aluminium accounts for this lack of reactivity?

Corrosion of metals

Pollutant gases are given off as vegetable matter undergoes bacterial decay. The bacterial decay of vegetable matter is the main source of which gas?

Air quality and climate

Lakes contain different dissolved substances. Which substance causes eutrophication in lakes?

Fertilisers

How many of the molecules shown are members of the homologous series of alkanes? $\text{C}_2\text{H}_4$, $\text{C}_3\text{H}_8$, $\text{C}_4\text{H}_{10}$, $\text{C}_5\text{H}_{10}$, $\text{C}_6\text{H}_{14}$

Alkanes

The diagram shows the structural formula of an organic compound. Which statement concerning this compound is correct?

Formulae, functional groups and terminology

Which of the following statements about vegetable oil and the margarine produced from it is correct?

Alkenes

Which functional group is present in alcohols?

Formulae, functional groups and terminology

An ester is produced when a carboxylic acid reacts with an alcohol. In what way does the number of carbon, hydrogen and oxygen atoms in an ester compare with the combined total of these atoms in the carboxylic acid and alcohol used to make it?

Formulae, functional groups and terminology

Which statement correctly describes the composition of polymers?

Polymers

Which of the statements are correct?

Elements, compounds and mixtures

Poly(styrene) is an addition polymer. A partial structure of poly(styrene) is displayed. What is the formula of the monomer used to make poly(styrene)?

Polymers

Which row indicates the numbers of particles in $^{34}_{16}\text{S}^{2-}$?

Isotopes

At room temperature, which substance has a giant covalent structure?

Giant covalent structures

Magnesium oxide melts only at a very high temperature, so it is used to line the inside of furnaces that run at high temperatures. Explain why magnesium oxide has such a high melting point.

Ion and ionic bonds

What does the dot-and-cross diagram for $\text{NCl}_3$ show?

Simple molecules and covalent bonds

Two characteristics of a metal are stated.

Properties of metals

On heating, magnesium combines with oxygen in the air to make magnesium oxide, a white powder. A student is investigating how the mass changes during this reaction. He is provided with a balance and three sets of apparatus, as shown. Which apparatus sets are appropriate for this investigation?

Experimental design

An incomplete equation for the reaction of ethyne, $\text{C}_2\text{H}_2$, with oxygen is given below. $2\text{C}_2\text{H}_2(g) + \ldots \text{O}_2(g) \rightarrow \ldots \text{CO}_2(g) + \ldots \text{H}_2\text{O}(g)$ After the equation has been balanced, what should the correct value of $\text{O}_2(g)$ be?

Fuels

By mass, a compound is made up of $40.0\%$ carbon, $6.7\%$ hydrogen and $53.3\%$ oxygen. Its relative molecular mass falls between 55 and 65. What is the molecular formula of this compound?

Formulae

What observations are made during the electrolysis of aqueous copper(II) sulfate when carbon electrodes are used?

Electrolysis

Four electrolysis processes are given below. 1 the electrolysis of concentrated aqueous sodium chloride 2 the electrolysis of dilute sulfuric acid 3 the extraction of aluminium from pure aluminium oxide 4 the purification of copper using aqueous copper(II) sulfate Which processes generate oxygen at one of the electrodes?

Electrolysis

Which statements regarding endothermic reactions are correct? 1 Energy is taken in from the surroundings. 2 Energy is given out to the surroundings. 3 The temperature of the reaction mixture decreases. 4 The temperature of the reaction mixture increases.

Exothermic and endothermic reactions

A fuel undergoes complete combustion in air. Carbon dioxide, water and heat are formed. Which energy profile diagram is correct for the combustion of a fuel?

Exothermic and endothermic reactions

This equation represents the reaction used in the production of ammonia. $\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightleftharpoons 2\text{NH}_3(\text{g})$ Which change would lower the activation energy of the reaction?

Rate of reaction

Solid ammonium chloride is heated. Ammonia and hydrogen chloride gases are produced. This is reaction 1. Ammonia gas is combined with hydrogen chloride gas. Solid ammonium chloride is produced. This is reaction 2. Which statement is correct?

Reversible reactions and equilibrium

Inside a sealed flask, gases Q and R establish a dynamic equilibrium. $\text{Q}(\text{g}) \rightleftharpoons 2\text{R}(\text{g}) \qquad \Delta H \text{ is positive}$ Which alteration will shift the equilibrium towards the right-hand side?

Reversible reactions and equilibrium

Which reaction is a redox reaction?

Redox

Four substances are warmed carefully. The temperatures at which melting begins and ends are noted. Which of the following statements about the substances is correct?

Elements, compounds and mixtures

Three different solution-and-solid mixtures are prepared, as shown in the table. The mixtures are then heated. In which mixtures is gas produced?

Physical and chemical changes

A metal’s carbonate, chloride and sulfate are all soluble in water. Which metal is it?

Group I properties

Which fertiliser has the greatest percentage of nitrogen by mass?

Fertilisers

Which combination of conditions is employed in the contact process?

Preparation of salts

The diagram depicts part of the Periodic Table. Which two letters show elements that are able to react with each other to make covalent compounds?

Simple molecules and covalent bonds

The Group I metals lithium, sodium and potassium display patterns in their melting points and in how they react with water. Which statement is correct as you move down the group from lithium to potassium?

Group I properties

From where vanadium, chromium and cobalt are located in the Periodic Table, what properties would you anticipate these elements to show?

Transition elements

The diagram illustrates the arrangement of particles in an alloy. Which statement about alloys is correct?

Alloys and their properties

Which pair of reagents will take part in a displacement reaction?

Reactivity series

A reactivity series for some metals is shown, with two gaps marked $X$ and $Y$. Which row gives the correct metals $X$ and $Y$ and the extraction method used to obtain $Y$ from its ore?

Extraction of metals

A compound dissolves in water and produces a colourless solution. If this solution is mixed with aqueous silver nitrate in the presence of dilute nitric acid, a yellow precipitate is formed. What is the likely identity of the substance?

Identification of ions and gases

Iron may be obtained from the ore haematite, $\text{Fe}_2\text{O}_3$. What is the greatest mass of iron that could be formed from $500\,\text{kg}$ of haematite? $[\text{Ar}:\ \text{O}=16,\ \text{Fe}=56]$

Relative masses of atoms and molecules

Aluminium is used to make saucepans because it seems to be relatively unreactive. Which property of aluminium accounts for this unreactivity?

Corrosion of metals

Bacterial decomposition of vegetable matter gives off pollutant gases. The bacterial decay of vegetable matter is the main source of which gas?

Air quality and climate

A number of different treatments are used to clean the water supply. Which impurities are removed by each treatment?

Water

Which statement concerning the homologous series of alkanes is correct?

Alkanes

Which compound has an empirical formula with the largest relative formula mass?

Relative masses of atoms and molecules

Which of the following statements about vegetable oil and the margarine produced from it is correct?

Alkenes

When ethene combines with steam to make ethanol, what kind of reaction is this?

Alkenes

An ester is made when a carboxylic acid reacts with an alcohol. In what way do the numbers of carbon, hydrogen and oxygen atoms in an ester compare with the combined numbers of these atoms in the carboxylic acid and alcohol used to make it?

Carboxylic acids

Poly(lactic) acid is a polymer that is used to produce biodegradable cups. The partial structure of poly(lactic) acid is shown. Which statements are true for poly(lactic) acid?

Polymers

Which of the following statements is correct?

Elements, compounds and mixtures

Two large molecules, $P$ and $Q$, each have the same linkage. $P$ is found in nature, whereas $Q$ is not. Which row could represent $P$ and $Q$?

Polymers

Which particle has the largest number of electrons?

Atomic structure and the Periodic Table

At room temperature, which substance has a giant covalent structure?

Giant covalent structures

An ionic compound is formed when 1 atom of element X reacts with 2 atoms of element Y. Element X produces a positive ion. Which elements might X and Y be?

Ion and ionic bonds

An element with a high melting point forms an oxide that is gaseous at room temperature. What kind of structure or bonding is present in the element?

Giant covalent structures

Which statement gives the reason aluminium is malleable?

Properties of metals

Five atoms are represented by their electronic configurations, which are labelled A, B, C, D and E.

Atomic structure and the Periodic Table

When zinc is placed in aqueous nickel(II) nitrate, $\text{Zn}(s)+\text{Ni(NO}_3)_2(aq)\rightarrow \text{Zn(NO}_3)_2(aq)+\text{Ni}(s)$.

Electrolysis

Tartaric acid and succinic acid are colourless organic acids, and their structures are displayed below.

Formulae, functional groups and terminology

The alkanes form a homologous series made up of saturated hydrocarbons.

Alkanes

The Periodic Table arranges elements into groups and periods.

Atomic structure and the Periodic Table

The table shows several properties of the Group V elements.

Arrangement of elements

Respiration produces carbon dioxide and water.

Polymers

Chromium belongs to the transition elements. Sodium is an element in Group I of the Periodic Table.

Transition elements

Cerium is a metal whose relative atomic mass is 140. Cerium powder undergoes reaction with sulfuric acid. $2\text{Ce}(s)+3\text{H}_2\text{SO}_4(aq)\rightarrow \text{Ce}_2(\text{SO}_4)_3(aq)+3\text{H}_2(g)$.

Rate of reaction

Five atoms are given together with their electronic configurations. They are identified as A, B, C, D and E.

Atomic structure and the Periodic Table

Magnesium undergoes a reaction with aqueous copper(II) sulfate. $\text{Mg(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{MgSO}_4\text{(aq)} + \text{Cu(s)}$

Electrolysis

The displayed structure of fumaric acid is shown.

Alkenes

Alkenes make up a homologous series of unsaturated hydrocarbons.

Alkenes

The Periodic Table is a system for arranging elements into groups and periods.

Arrangement of elements

A few properties of Group VI elements are given below.

Arrangement of elements

During photosynthesis, plants take carbon dioxide out of the air.

Polymers

Bismuth is a Group V metallic element in the Periodic Table.

Metallic bonding

When sulfuric acid reacts with zinc, zinc sulfate and hydrogen are produced. $\text{Zn(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{H}_2\text{(g)}$

Rate of reaction

State the names of the apparatus shown. Use the labels $P$ and $Q$.

Experimental design

The table gives the properties of three gases, $A$, $B$ and $C$.

Solids, liquids and gases

Mixing aqueous sodium thiosulfate, $\text{Na}_2\text{S}_2\text{O}_3$(aq), with dilute hydrochloric acid gives a pale yellow sulfur precipitate, so the reaction mixture turns cloudy. $\text{Na}_2\text{S}_2\text{O}_3$(aq) + 2HCl(aq) \rightarrow 2NaCl(aq) + S(s) + SO_2(g) + H_2O(l)$

Rate of reaction

Ethanedioic acid crystals are represented by the formula $H_2C_2O_4\cdot xH_2O$. A student uses titration to find the value of $x$.

Acid–base titrations

The student is given three bottles: dilute hydrochloric acid, aqueous sodium sulfate and ethanol.

Identification of ions and gases

Solid $L$ consists of a mixture of two compounds. Both compounds have the same cation, but their anions are different.

Identification of ions and gases

A student tries to work out the percentage of oxygen in air by using the apparatus shown.

Air quality and climate

The diagram shows two items of laboratory apparatus, marked A and B.

Experimental design

A student carries out two electrolysis experiments with the apparatus shown.

Electrolysis

Calcium carbonate undergoes reaction with dilute hydrochloric acid. $\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{CO}_2(g) + \text{H}_2\text{O}(l)$ A student investigates the way the rate of this reaction changes when the temperature is increased.

Rate of reaction

A student has been given three bottles of different aqueous solutions together with some reagents.

Identification of ions and gases

A student uses a titration method to find the percentage of iron in a powdered sample of impure iron.

Acid–base titrations

Solid L is made up of two compounds. Each compound contains a different cation but the same anion.

Identification of ions and gases

When aqueous lead(II) nitrate reacts with aqueous potassium iodide, lead(II) iodide is formed as a precipitate. $\text{Pb(NO}_3)_2(aq) + 2\text{KI}(aq) \rightarrow \text{PbI}_2(s) + 2\text{KNO}_3(aq)$

Experimental design