Oct/Nov 2016

A student is provided with just the nucleon number of an atom. What information about the atom's structure can be inferred?

Isotopes

Which diagram most accurately shows the structure of a solid metal?

Metallic bonding

A compound made up solely of carbon and hydrogen contains $80.0\%$ carbon by mass. Determine its empirical formula?

Formulae

The formula of an ionic compound is $XY$, and $Y$ is a non-metal. Which statement correctly describes $XY$?

Ion and ionic bonds

In one experiment, $1\,\text{cm}^3$ of a gaseous hydrocarbon, $Z$, needs $4\,\text{cm}^3$ of oxygen for complete combustion and produces $3\,\text{cm}^3$ of carbon dioxide. All gas volumes are taken at r.t.p. Which formula shows $Z$?

Fuels

An aqueous solution of copper(II) sulfate is electrolysed, with copper used as the positive electrode and carbon used as the negative electrode. Which row gives the correct information for this electrolysis?

Electrolysis

Four metals are electrolysed as molten salts. For one mole of atoms to be released in the electrolysis, the ions of which metal need the fewest electrons?

Electrolysis

Which two products are made during photosynthesis?

Air quality and climate

A student carries out an investigation into how the concentration of a reagent influences the rate of a chemical reaction. Which piece of apparatus is needed for every rate investigation?

Rate of reaction

Gold is used as a catalyst in some chemical reactions. In these reactions, gold: • lowers the energy cost of the reaction. • raises the yield of the reaction. • remains unchanged at the end of the reaction. • increases the speed of the reaction. How many of these statements are true?

Rate of reaction

The table gives some properties of four metal chlorides. Which row is magnesium chloride?

Ion and ionic bonds

Two experiments were conducted. In experiment 1, ammonium carbonate reacted with dilute hydrochloric acid. In experiment 2, ammonium carbonate was heated with aqueous sodium hydroxide. For each experiment, the gas given off was tested using damp blue litmus paper and damp red litmus paper. Which row correctly indicates the colour of both pieces of litmus paper at the end of each experiment?

The characteristic properties of acids and bases

A piece of element $X$ can be sliced with a knife. As $X$ reacts with water, it floats and becomes molten. Which element is $X$?

Group I properties

Which row gives the pH values for $0.1\,\text{mol dm}^{-3}$ solutions of ammonia, hydrochloric acid, sodium chloride and sodium hydroxide?

The characteristic properties of acids and bases

The diagram illustrates the equipment used to obtain aluminium from aluminium oxide. Which statement about this process is correct?

Extraction of metals

A student is given five reagents: dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, solid calcium carbonate, and solid copper(II) carbonate. How many soluble salts could be prepared?

Preparation of salts

Which of the reactions is not a redox reaction?

Redox

The following properties can be used to distinguish elements from one another: 1 metallic character, 2 number of electron shells in an atom, 3 number of protons in an atom, 4 total number of electrons in an atom. Which two of these properties increase across a period of the Periodic Table?

Arrangement of elements

An aqueous copper(II) sulfate solution is put into an iron container and left for several days. Which statement describes the change that occurs?

Reactivity series

Which equation represents a reaction that takes place at room temperature and pressure?

Rate of reaction

Fixing pieces of magnesium onto iron pipes that are buried underground can prevent the iron from corroding. Which reaction is responsible for protecting the iron from corrosion?

Corrosion of metals

Which compound is employed as a fertiliser?

Fertilisers

In a paper chromatography experiment, an $R_f$ value is determined for $\text{Fe}^{3+}(aq)$. The outcome is shown. To make the spot containing $\text{Fe}^{3+}(aq)$ easier to see, the paper is sprayed with aqueous sodium hydroxide, causing a precipitate of iron(III) hydroxide to form. For the conditions used in the experiment, the $R_f$ of $\text{Fe}^{3+}(aq)$ is ______ and the colour of the precipitate is ______. Which row correctly fills gaps 1 and 2?

Chromatography

During the Haber process, hydrogen and nitrogen combine to produce ammonia in the presence of a catalyst. Which of these two reactants is separated by fractional distillation, and what catalyst is used in the Haber process?

Reversible reactions and equilibrium

An element, $Z$, in Group II of the Periodic Table combines with chlorine, an element in Group VII. What is the formula of the ionic compound that is produced?

Ion and ionic bonds

The table outlines treatments applied to drinking water supplies and the reasons for applying them. Which row is correct?

Water

The table sets out some atmospheric pollutants and their possible effects. Which row is incorrect?

Air quality and climate

How many moles of ethanoic acid, $\text{CH}_3\text{CO}_2\text{H}$, are needed to react with one mole of magnesium?

The characteristic properties of acids and bases

With which substance does ethene react to produce more than one product?

Alkenes

The diagram presents the structures of two hydrocarbons, X and Y. Two students give the following statements. Student 1: Hydrocarbon X is an isomer of Y. Student 2: Hydrocarbon X is unsaturated whereas Y is saturated. Which students are correct?

Formulae, functional groups and terminology

The diagram illustrates the structure of an ester. State the name of this ester.

Naming organic compounds

A hydrocarbon that is unsaturated and has six carbon atoms contains only three C=C double bonds. This hydrocarbon is then reacted with excess hydrogen at a high temperature. What is the formula of the hydrocarbon formed?

Alkanes

Compound Q is represented by the formula $\text{C}_4\text{H}_{10}$. Which statement concerning compound Q is correct?

Alkanes

The graph shows the melting points (m.p.) of lead-tin mixtures. From the graph, it can be seen that every mixture of lead and tin must have a melting point that is

Alloys and their properties

Hydrolysis of R, a macromolecule, yields a mixture of amino acids. What is R?

Polymers

Some students made three claims about the bonding in a molecule of ammonia, $\text{NH}_3$. 1. Because a nitrogen atom has three outer electrons, every outer electron takes part in bonding. 2. A nitrogen atom has five outer electrons, so two of its outer electrons are not used in bonding. 3. A nitrogen atom shares electrons with each of the three hydrogen atoms. Which of these statements about bonding in ammonia are correct?

Simple molecules and covalent bonds

Which diagram accurately represents how the ions are arranged in solid sodium chloride?

Ion and ionic bonds

The table presents some properties of four solid elements. Which element might be graphite?

Giant covalent structures

Which of the following statements about chlorine atoms and chloride ions is correct?

Ion and ionic bonds

The four gases below are given. 1 $\text{CH}_4$ 2 $\text{NH}_3$ 3 $\text{CO}_2$ 4 $\text{N}_2$ A $1\,\text{mol dm}^{-3}$ sample of each of gases 1-4 is allowed to diffuse. In what sequence do their diffusion rates occur at room temperature and pressure?

Diffusion

Under identical conditions, which gas diffuses at the same rate as nitrogen?

Diffusion

Which diagram correctly represents how the ions are arranged in solid sodium chloride?

Ion and ionic bonds

Add aqueous sodium hydroxide to one portion of a colourless solution. Add aqueous ammonia to another separate portion of the same colourless solution. In each test, a white precipitate is produced and then dissolves in excess reagent. Which positive ion is present in the solution?

Identification of ions and gases

During an experiment, $1\,\text{cm}^3$ of a gaseous hydrocarbon, $Z$, needs $4\,\text{cm}^3$ of oxygen for complete combustion, producing $3\,\text{cm}^3$ of carbon dioxide. Every gas volume is taken at r.t.p. Which formula represents $Z$?

Fuels

Which material is the best conductor of electricity?

Properties of metals

Molten salts of four metals are electrolysed. For the ions of which metal is the fewest number of electrons needed to release one mole of atoms during electrolysis?

Electrolysis

A reaction that absorbs heat has an activation energy of $x$. Which energy profile diagram shows this reaction correctly?

Exothermic and endothermic reactions

The statements below are about how catalysts are used in chemical reactions. Which statements are correct?

Rate of reaction

In two experiments, 1 and 2, an excess of powdered calcium carbonate was added in a flask to dilute hydrochloric acid. For experiment 1, the carbon dioxide produced was collected, and the gas volume was recorded at regular intervals. For experiment 2, the mass of the flask and its contents was recorded at regular intervals. The outcomes from both experiments were then plotted on graphs. Which graphs correctly represent the results of these two experiments?

Rate of reaction

Chlorine reacts with iron(II) ions. $2\text{Fe}^{2+}(aq) + \text{Cl}_2(g) \rightarrow 2\text{Fe}^{3+}(aq) + 2\text{Cl}^-(aq)$ Which of the following statements about this reaction is correct?

Redox

In liquid water, a small amount of ionisation occurs. $\text{H}_2\text{O}(l) \rightleftharpoons \text{H}^+(aq) + \text{OH}^-(aq)$ The forward reaction absorbs heat. If the temperature of the water is raised, what change(s) occur?

Reversible reactions and equilibrium

When calcium carbonate is combined with dilute hydrochloric acid, carbon dioxide gas is given off. Three groups of apparatus are displayed. Which groups of apparatus are suitable, together with a stopwatch, for monitoring the rate of this reaction?

Rate of reaction

The table displays some properties of four metal chlorides. Which row represents magnesium chloride?

Ion and ionic bonds

Which statement about how metals are used is incorrect?

Uses of metals

A piece of element X can be sliced with a knife. When X reacts with water, it floats and becomes molten. Identify X.

Group I properties

Which row contains a transition element?

Transition elements

Element Z reacts with sodium to make the compound $\text{Na}_2\text{Z}$. The locations of four elements are displayed on the outline of part of the Periodic Table. Which element is Z?

Arrangement of elements

The table lists the observations obtained after various reagents were added to an aqueous solution of salt Z. What is Z?

Identification of ions and gases

The diagram illustrates the apparatus used to obtain aluminium from aluminium oxide. Which statement about this process is correct?

Extraction of metals

Which reaction does not involve a redox reaction?

Redox

An iron container is filled with aqueous copper(II) sulfate solution and then left undisturbed for several days. Which statement describes the outcome?

Reactivity series

During paper production, sulfur dioxide is added to take away the yellow colour from the wood pulp. Which term can be used to describe sulfur dioxide in this process?

Redox

Which of the following statements is correct?

Elements, compounds and mixtures

Which of the following statements about the uses of gases is incorrect?

Solids, liquids and gases

Electrical energy can be produced by using simple cells as shown. Which pair of metals, when used as electrodes, will produce the greatest reading on the voltmeter, $V$?

Reactivity series

When $0.002$ moles of a metal $M$ were reacted with an excess of dilute hydrochloric acid, $48\,\text{cm}^3$ of hydrogen was produced at r.t.p. Which equation is correct for this reaction?

The characteristic properties of acids and bases

The diagram shows part of a polymer chain. Which alkene was used to produce this polymer?

Polymers

The table lists some atmospheric pollutants and their possible effects. Which row is incorrect?

Air quality and climate

Which compound has the greatest viscosity and is the least flammable?

Alcohols

One mole of magnesium reacts with how many moles of ethanoic acid, $\text{CH}_3\text{CO}_2\text{H}$?

The mole and the Avogadro constant

Which substance reacts with ethene to produce more than one product?

Alkenes

Which claim about a compound’s isomers is always true?

Formulae, functional groups and terminology

How many of the structures contain an unsaturated hydrocarbon molecule?

Alkenes

Benzene and cyclohexane are both flammable liquids. They can be blended together without forming separate layers. Their boiling points are very close to one another. Because of this, a mixture of these two liquids is hard to separate by fractional distillation. Why is it hard to separate a mixture of benzene and cyclohexane by fractional distillation?

Separation and purification

What type of polymer is formed when amino acids react with each other?

Polymers

The graph shows the melting points (m.p.) for mixtures made from lead and tin. It indicates that every lead-and-tin mixture must have a melting point that is

Alloys and their properties

Which of the following statements about chlorine atoms and chloride ions is true?

Ion and ionic bonds

As substance Q changes from solid to liquid, only the weak forces of attraction between its molecules are overcome. Which row gives the correct description of Q?

Simple molecules and covalent bonds

When a solution containing lead(II) ions is combined with a solution containing iodide ions, a yellow precipitate is produced. What is the equation for the reaction taking place?

Identification of ions and gases

Buckminsterfullerene has the chemical formula $\text{C}_{60}$. Which description best fits the structure of buckminsterfullerene?

Simple molecules and covalent bonds

Select from the compounds listed below to answer the questions that follow. Ba(NO$_3$)$_2$ CaCO$_3$ CaO CH$_4$ C$_3$H$_8$ Fe$_2$O$_3$ KMnO$_4$ NaNO$_3$ NO SO$_2$ V$_2$O$_5$ Zn(NO$_3$)$_2$ Each compound may be used once, more than once, or not used at all. Which compound

Identification of ions and gases

Sulfuric acid counts as a strong acid.

The characteristic properties of acids and bases

Alcohols belong to a homologous series with general formula C$_n$H$_{2n+1}$OH. The table gives some details about different alcohols.

Alcohols

In aqueous solution, peroxodisulfate ions, S$_2$O$_8^{2-}$, react with iodide ions. S$_2$O$_8^{2-}$(aq) + 2I$^-$(aq) $\rightarrow$ 2SO$_4^{2-}$(aq) + I$_2$(aq) The table displays how the relative rate of this reaction varies when different concentrations of peroxodisulfate ions and iodide ions are used.

Rate of reaction

Potassium chlorate, KClO$_3$, breaks down to give potassium chloride and oxygen. 2KClO$_3$(s) $\rightarrow$ 2KCl(s) + 3O$_2$(g)

The mole and the Avogadro constant

Dry air is made up of nitrogen, oxygen, argon and other gases.

Noble gases

Pick answers for the questions below from the compounds listed here. BaCl$_2$ C$_2$H$_4$ C$_3$H$_4$ C$_3$H$_8$ CO CO$_2$ K$_2$SO$_4$ Na$_3$PO$_4$ SO$_2$ ZnSO$_4$ Any of these compounds may be used once, more than once, or not used at all.

Identification of ions and gases

A student produced hydrated copper(II) sulfate crystals by allowing excess insoluble copper(II) oxide to react with dilute sulfuric acid. CuO + H$_2$SO$_4$ + 4H$_2$O $\rightarrow$ CuSO$_4\cdot$5H$_2$O

Separation and purification

Farmers apply fertilisers such as ammonium sulfate to the soil so that plant growth happens more quickly.

Identification of ions and gases

Hydrocarbons in the alkane family form a homologous series.

Alkanes

Propanone, CH$_3$COCH$_3$, reacts with iodine, I$_2$, to make colourless products. CH$_3$COCH$_3$ + I$_2$ $\rightarrow$ CH$_3$COCH$_2$I + HI Hydrochloric acid is the catalyst for this reaction. The table shows how the relative rate of reaction changes when different concentrations of propanone, iodine and hydrochloric acid are used.

Rate of reaction

Nickel carbonyl, Ni(CO)$_4$, undergoes reaction with hydrogen iodide. Ni(CO)$_4(l)$ + 2HI$(g)$ $\rightarrow$ NiI$_2(s)$ + H$_2(g)$ + 4CO$(g)$

The mole and the Avogadro constant

Sodium and rubidium are part of the alkali metals.

Group I properties

Within the contact process, sulfur trioxide is formed by catalytic oxidation of sulfur dioxide. In a sealed vessel, the following equilibrium is established. 2SO$_2(g)$ + O$_2(g)$ $\rightleftharpoons$ 2SO$_3(g)$ The reaction is exothermic.

Reversible reactions and equilibrium

Propenenitrile, CH$_2$=CHCN, is produced by passing propene, ammonia and oxygen over a catalyst at 450$^\circ$C. CH$_3$CH=CH$_2$ + NH$_3$ + $\tfrac{3}{2}$O$_2$ $\rightarrow$ CH$_2$=CHCN + 3H$_2$O The reaction releases heat.

Polymers

Copper and magnesium are both metals.

Alloys and their properties

A student uses the apparatus shown to separate a mixture of pentane and hexane. Pentane is collected in the conical flask.

Separation and purification

A student carries out electrolysis on aqueous copper(II) sulfate with the apparatus shown. A solid forms at the cathode, and a gas forms at the anode.

Electrolysis

A student determines that a compound has $4.8\text{ g}$ of carbon, $0.8\text{ g}$ of hydrogen and $6.4\text{ g}$ of oxygen. $[A_r: \text{C}, 12; \text{H}, 1; \text{O}, 16]$

Formulae

Which of the following pairs of compounds, when dissolved in water, will not undergo a reaction to produce a precipitate?

Ion and ionic bonds

A student puts the catalyst manganese(IV) oxide into aqueous hydrogen peroxide, and the hydrogen peroxide breaks down: $\text{2H}_2\text{O}_2(aq) \rightarrow \text{2H}_2\text{O}(l) + \text{O}_2(g)$. The student then measures the volume of oxygen released at regular time intervals. This is experiment 1. The student carries out experiment 2 again, but with one altered condition. Graphs for experiments 1 and 2 are shown.

Rate of reaction

Copper(II) oxide and carbon are both black solids, but when Copper(II) oxide is treated with dilute sulfuric acid it forms aqueous copper(II) sulfate, whereas carbon shows no reaction with dilute sulfuric acid.

Separation and purification

Limestone is calcium carbonate that is not pure. A student carries out an experiment to determine the percentage by mass of calcium carbonate in a limestone sample. The limestone is put into a container that has already been weighed, and the container is weighed again. mass of container + limestone = $10.22\text{ g}$ mass of empty container = $5.72\text{ g}$

Acid–base titrations

The table outlines the tests carried out by a student on compound $L$. $L$ contains three different ions. Fill in the table by giving the conclusion for (a), the observations for (b)(i), (ii) and (iii), the conclusions for (c)(i) and (ii), and both the test and the observation that support the conclusion for test (d). Any gases given off should be identified by test, result and name.

Identification of ions and gases

When magnesium powder is introduced into excess hydrochloric acid, the temperature increases.

Exothermic and endothermic reactions

A student oxidises ethanol to ethanoic acid using acidified aqueous potassium manganate(VII).

Carboxylic acids

After metal $M$ is put into aqueous copper(II) sulfate, the temperature rises.

The mole and the Avogadro constant

The apparatus in the diagram is used to carry out electrolysis of dilute sulfuric acid.

Electrolysis

A student combusts $4.8\,\text{g}$ of an element $X$ in excess oxygen. The mass of the oxide formed is $8.0\,\text{g}$. [$A_r: X,\,24;\,O,\,16$]

Formulae

The chromatogram displays the chromatography results for mixture $Z$, alongside the separate dyes marked $1$, $2$, $3$ and $4$.

Chromatography

A student puts excess zinc into hydrochloric acid and notes the volume of hydrogen gas released at regular time intervals. In experiment 2, the student alters one condition. The volume of hydrochloric acid is unchanged in both experiments.

Rate of reaction

A student moves air backwards and forwards over heated copper. The air originally occupies $50.0\,\text{cm}^3$ in the apparatus.

Air quality and climate

Vinegar is a dilute solution of ethanoic acid. Different brands of vinegar have different ethanoic acid concentrations. Two separate brands of colourless vinegar are supplied.

Acid–base titrations

A student carries out an experiment to work out the percentage by mass of copper in an impure copper sample.

The mole and the Avogadro constant

The table below lists the tests that a student performs on mixture $L$, which is composed of two compounds. $L$ contains three different ions.

Identification of ions and gases