May/June 2016

Identify the oxide that is amphoteric.

Oxides

Which of these uses of sulfuric acid are correct?

The characteristic properties of acids and bases

When Group I metals combine with Group VII halogens, compounds are produced. These compounds are ……1…… in water and contain ……2…… bonds. Which words correctly fill gaps 1 and 2?

Ion and ionic bonds

P is the only substance produced when two volumes of ammonia gas react with one volume of carbon dioxide gas, with both volumes measured at r.t.p. What is the formula of P?

The mole and the Avogadro constant

Chlorine has two isotopes, $^{35}\text{Cl}$ and $^{37}\text{Cl}$. With these isotopes, how many distinct relative molecular masses can the compound with molecular formula $\text{C}_2\text{H}_3\text{Cl}_3$ have?

Isotopes

Gases are able to diffuse through porous pots. The diagram shows a beaker filled with nitrogen turned upside down over a porous pot that contains carbon monoxide. The water level stays still. Which statement explains this?

Diffusion

Carbon electrodes are used to electrolyse aqueous copper(II) sulfate. Which observations would be seen?

Electrolysis

Which ion is absent in dilute sulfuric acid?

The characteristic properties of acids and bases

The diagram illustrates the energy profile of a chemical reaction, displayed both with and without a catalyst. Which energy change corresponds to the activation energy for the catalysed reaction?

Rate of reaction

Which equation is not a redox reaction?

Redox

The diagram illustrates the apparatus used to determine the rate of reaction between calcium carbonate and dilute hydrochloric acid. The mass of the flask and its contents is recorded at regular time intervals. Which graph correctly indicates how the mass of the flask and contents varies with time?

Rate of reaction

Four gas jars each hold one of the gases ammonia, chlorine, hydrogen chloride and oxygen. In every jar, a strip of damp blue litmus paper and a strip of damp red litmus paper are added. In which gas jar do both the damp blue litmus paper and the damp red litmus paper change colour?

The characteristic properties of acids and bases

Which row gives the correct comparison between high carbon steels and low carbon steels?

Alloys and their properties

Which process does not make use of a catalyst?

Rate of reaction

Gaseous compound X acts as an oxidising agent. X is passed as bubbles through separate solutions of aqueous potassium iodide and acidified potassium manganate(VII). Which row shows the colour changes observed when X is bubbled through these two solutions?

Redox

By heating with iron, which metal oxide is reduced?

Reactivity series

Which two substances can be mixed with water and stirred to make a sample of lead(II) chloride?

Preparation of salts

An aqueous hydrochloric acid solution has a pH of 2. After $10\,\text{g}$ of sodium chloride has been added, what would the pH of the acid be?

The characteristic properties of acids and bases

Which statement concerning the elements in the Periodic Table is correct?

Atomic structure and the Periodic Table

The extraction of iron from haematite takes place in the blast furnace. Which other raw material is introduced for this extraction?

Extraction of metals

The diagram illustrates a flow chart for producing fertiliser. In the flow chart, what are W, X, Y and Z?

Fertilisers

The table shows the melting points, densities and electrical conductivities of four elements. Which element is copper?

Properties of metals

How can a pure sample of barium sulfate be prepared from barium carbonate?

Preparation of salts

Which gases are present at the positive electrode during aluminium manufacture?

Electrolysis

The diagram illustrates the structure of brass. Why does brass have a greater hardness than pure copper?

Alloys and their properties

Which pollutant is responsible for eutrophication in rivers?

Water

When 1 mole of methane reacts with a large excess of chlorine in sunlight, how many moles of hydrogen chloride are formed?

Alkanes

Which of the following statements about alcohols are correct?

Alcohols

Amino acids are vital building blocks in the human body. Macromolecules present in food are broken down by hydrolysis to produce amino acids. Which macromolecules supply the body with amino acids?

Polymers

Ethanol, $\text{C}_2\text{H}_6\text{O}$, was allowed to react with propanoic acid, $\text{C}_3\text{H}_6\text{O}_2$, with concentrated sulfuric acid present. Which statement about the organic product from this reaction is correct?

Formulae, functional groups and terminology

How can alkenes be produced?

Alkenes

Which statement concerning alkanes is correct?

Alkanes

Which statement concerning ethanoic acid is correct?

Carboxylic acids

Which statement is incorrect?

Elements, compounds and mixtures

Polymer Z is shown in the diagram. The following four terms may be used when describing polymers. 1 addition polymer 2 condensation polymer 3 polyamide 4 polyester Which two terms apply to polymer Z?

Polymers

The symbols of two ions are displayed, $^{19}_{9}\text{F}^-$ and $^{21}_{11}\text{Na}^+$. Which statement is correct?

Atomic structure and the Periodic Table

Which dot-and-cross diagram, with every outer-shell electron for each atom shown, is incorrect?

Simple molecules and covalent bonds

Which statement indicates that graphite and diamond are different forms of the element carbon?

Giant covalent structures

For a compound with oxygen to be formed, an atom of a Group II element must

Ion and ionic bonds

Copper wire is used to close an electrical circuit. What takes place in the copper wire?

Metallic bonding

Which row correctly names the gas?

Identification of ions and gases

P is the sole product made when two volumes of ammonia gas combine with one volume of carbon dioxide gas, with both volumes measured at r.t.p. What is the formula of P?

The mole and the Avogadro constant

Gases are able to diffuse through porous pots. The diagram shows a beaker filled with nitrogen turned upside down above a porous pot containing carbon monoxide. The water level remains unchanged. Which statement explains this?

Diffusion

Copper is purified by electrolysis. Which statement is incorrect?

Electrolysis

An aqueous sodium chloride solution of high concentration is electrolysed with inert electrodes until chlorine gas is no longer produced. What might the pH of the solution that remains be?

Electrolysis

Ammonia may be manufactured on an industrial scale from nitrogen and hydrogen. $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$. The forward reaction is exothermic. Which change would leave the ammonia yield unchanged?

Reversible reactions and equilibrium

The diagram illustrates an energy profile for a chemical reaction, shown both in the presence of a catalyst and in its absence. Which energy change represents the activation energy for the catalysed reaction?

Rate of reaction

Oil will float on water. Which statement about oil and water is not true?

Solids, liquids and gases

Which process does not use a catalyst?

Rate of reaction

Which statement is not a description of a reduction reaction?

Redox

An aqueous solution of hydrochloric acid has a pH of $2$. After $10\,\text{g}$ of sodium chloride is added, what is the pH of the acid?

The characteristic properties of acids and bases

A student is planning two experiments. Experiment 1: determine the concentration of a sodium hydroxide solution by titration using dilute hydrochloric acid Experiment 2: determine the rate of the reaction between pieces of calcium carbonate and dilute hydrochloric acid by recording the volume of gas released every minute A flask is already provided. What other apparatus is required?

Experimental design

Samples containing one mole of each solid carbonate of lead, calcium, barium and magnesium are reacted separately with excess dilute sulfuric acid. Which carbonate sample will produce the largest volume of carbon dioxide?

Preparation of salts

In which reaction do two of the products consist of salts?

Preparation of salts

The diagram shows how brass is structured. Why does brass have a greater hardness than pure copper?

Alloys and their properties

From their position in the Periodic Table, which statement is true?

Arrangement of elements

The table shows the melting points, densities and electrical conductivities of four elements. Which one is copper?

Properties of metals

A single atom of an element contains only eight electrons. Which statement about this element is correct?

Atomic structure and the Periodic Table

The diagram illustrates a flow chart for producing fertiliser. In the flow chart, what do W, X, Y and Z represent?

Fertilisers

By roasting with powdered iron, which oxide is reduced to the metal?

Extraction of metals

Which element, when connected to iron placed in salt water, would stop the iron from corroding?

Corrosion of metals

During the last stage of extracting metal X, the reaction is given by the equation: $\text{X}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{X} + 3\text{CO}_2$. Which element is X?

Extraction of metals

Q consists of a pure sample of a substance with one $R_f$ value of $0.9$. In the chromatogram shown, which letter corresponds to Q?

Chromatography

Hydrated sodium carbonate breaks down when it is heated in a Bunsen burner flame. Which equation represents this decomposition correctly?

Physical and chemical changes

Aluminium is obtained from aluminium oxide using electrolysis. Which statement about this electrolysis is correct?

Extraction of metals

Which ion is found in both sewage and fertilisers and may lead to eutrophication when it gets into rivers?

Fertilisers

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

Air quality and climate

How many of the structures displayed are unsaturated hydrocarbon molecules?

Formulae, functional groups and terminology

Which of the following statements are true for alkenes but not for alkanes?

Alkenes

Wine is an alcoholic drink containing ethanol. When wine is kept in contact with air for too long, it may turn acidic. This happens because the ethanol is ......1...... to the acid ......2...... . Which word and formula correctly fill gaps 1 and 2?

Alcohols

The structure of polymer Z is shown below. The following four terms may be used to classify polymers. 1 addition polymer 2 condensation polymer 3 polyamide 4 polyester Which two terms apply to polymer Z?

Polymers

The diagram illustrates the structure of poly(dichloroethene). Which statement about this polymer is correct?

Polymers

What description best fits the following reaction? $\text{C}_8\text{H}_{18} \rightarrow \text{C}_4\text{H}_{10} + 2\text{C}_2\text{H}_4$

Alkanes

Which statement about the isotopes of bromine is correct? They are atoms that have the same number of

Isotopes

The structures of four hydrocarbons, W, X, Y and Z, are shown. Which row is correct?

Naming organic compounds

Compound Z consists of element X and element Y. It conducts electricity well when it is molten, but it does not conduct when it is solid. Which statement is correct?

Ion and ionic bonds

Copper wire is used to make an electrical circuit complete. What occurs in the copper wire?

Properties of metals

Which statement indicates that graphite and diamond are different forms of the element carbon?

Elements, compounds and mixtures

Ethene, $\text{C}_2\text{H}_4$, is a covalent compound that has a simple molecular structure. Which of the following statements about ethene is correct?

Simple molecules and covalent bonds

An organic compound is represented by the molecular formula $\text{C}_8\text{H}_{16}\text{O}_4$. Determine the empirical formula of this compound.

Formulae

Select from the polymers below when answering the questions. Terylene, PTFE, nylon, starch, poly(propene), PVC, protein, polyester, poly(ethene). Any polymer may be used once, more than once, or not used at all.

Polymers

Zinc and iron both react with dilute sulfuric acid.

Reactivity series

Hydrogen sulfide, H$_2$S, has a straightforward molecular structure and dissolves in water.

The characteristic properties of acids and bases

Esters, such as propyl ethanoate, are frequently employed as solvents.

Diffusion

Ammonia is produced in the Haber process by reacting hydrogen with nitrogen.

Reversible reactions and equilibrium

The statements provide some chemical characteristics of metal X and its compounds.

Reactivity series

The atmosphere is made up of many gases, among them oxygen, nitrogen, carbon dioxide, sulfur dioxide, oxides of nitrogen, methane and chlorofluorocarbons (CFCs).

Air quality and climate

The formula of silver nitrate is AgNO$_3$.

Preparation of salts

Cyclohexane, C$_6$H$_{12}$, is one of the cycloalkanes.

Alkanes

In this reversible reaction, carbon reacts with steam. $\text{C(s)} + \text{H}_2\text{O(g)} \rightleftharpoons \text{H}_2\text{(g)} + \text{CO(g)} \quad \Delta H = +131\,\text{kJ mol}^{-1}$

Reversible reactions and equilibrium

Use the polymers listed below to answer the questions. Each polymer may be selected once, more than once, or not at all.

Polymers

Hydrogen fluoride, HF, consists of simple molecules. It dissolves in water.

The characteristic properties of acids and bases

Esters serve as food flavourings and as solvents.

Formulae, functional groups and terminology

Sulfuric acid is produced by the contact process.

Reversible reactions and equilibrium

The statements describe several chemical properties of cobalt and its compounds.

Reactivity series

Dissolved minerals and gases are present in river water.

Water

Lead(II) nitrate has the formula Pb(NO$_3$)$_2$.

Preparation of salts

The laboratory contains the apparatus shown below. The diagrams illustrate three techniques for collecting gases.

Experimental design

What colour does litmus paper turn when placed in hydrochloric acid?

The characteristic properties of acids and bases

For questions 3 to 6 inclusive, mark the correct answer by placing a tick (✓) in the box beside it.

Separation and purification

What volume of carbon dioxide gas, at room temperature and pressure, is formed when $9.2\,\text{g}$ of ethanol burns in excess oxygen? $\text{C}_2\text{H}_5\text{OH} + 3\text{O}_2 \rightarrow 2\text{CO}_2 + 3\text{H}_2\text{O}$ $[1\text{ mole of a gas occupies }24000\,\text{cm}^3\text{ at room temperature and pressure.}]$

The mole and the Avogadro constant

The diagram presents the energy profile for calcium hydroxide dissolving in water.

Exothermic and endothermic reactions

The diagram shows the apparatus for distilling seawater.

Separation and purification

A student is given a sample of an organic acid, V, and is told to work out its relative molecular mass and propose its molecular formula.

Acid–base titrations

L is a compound consisting of two ions.

Identification of ions and gases

On heating potassium chlorate(V), it decomposes and oxygen is released.

Rate of reaction

A student uses the apparatus shown to separate hexane, $\text{C}_6\text{H}_{14}$, (b.p. $69^{\circ}\text{C}$) from heptane, $\text{C}_7\text{H}_{16}$, (b.p. $98^{\circ}\text{C}$).

Separation and purification

State a test and the observation that would show that the nitrate ion, $\text{NO}_3^- (aq)$, is present.

Identification of ions and gases

On heating zinc in air, it reacts with oxygen to produce an oxide. A student carries out an experiment to determine the formula of zinc oxide.

Formulae

Chromatography may be used to separate the dyes in black ink.

Chromatography

A student is provided with a sample of damp soil that is known to be acidic.

The characteristic properties of acids and bases

A small piece of calcium is put into a test-tube of water that has been turned green by Universal Indicator.

Reactivity series

A student receives a sample of an organic acid and must work out its relative molecular mass and infer its molecular formula.

Acid–base titrations

M is a compound that consists of two ions.

Ion and ionic bonds

When aqueous barium chloride reacts with dilute sulfuric acid, barium sulfate is produced as a precipitate. $\text{BaCl}_2(aq) + \text{H}_2\text{SO}_4(aq) \rightarrow 2\text{HCl}(aq) + \text{BaSO}_4(s)$

The mole and the Avogadro constant