Oct/Nov 2020

A student has to measure $17.60\,\text{cm}^3$ of hydrochloric acid. The student can use the apparatus usually available in a school laboratory. Which item of equipment should be used to measure the $17.60\,\text{cm}^3$ of hydrochloric acid?

Experimental design

Which material has the greatest melting point?

Solids, liquids and gases

Which of the following statements describes ionic bonds?

Ion and ionic bonds

The diagram illustrates the covalent bonds present in an organic compound. The overall number of electrons in one molecule of this compound is .....X..... . The overall number of electrons in the bonds in one molecule of this compound is .....Y..... . Which numbers correctly fill gaps X and Y?

Simple molecules and covalent bonds

Which contains the largest mass of oxygen?

Relative masses of atoms and molecules

X contains, by mass, $63.6\%$ nitrogen and $36.4\%$ oxygen. State the empirical formula of X.

Formulae

The table shows the relative formula mass of four compounds and the mass of each compound contained in $1\,\text{dm}^3$ of solution. Which solution has the greatest concentration in $\text{mol dm}^{-3}$?

The mole and the Avogadro constant

Which sample has the greatest number of atoms?

The mole and the Avogadro constant

The diagrams display the structures of ethene and propene. Which statement about equal volumes of ethene gas and propene gas at r.t.p. is correct?

The mole and the Avogadro constant

Aqueous copper(II) sulfate is electrolysed with copper electrodes. The current remains constant, and the anode is weighed at regular intervals. Which graph is produced if the anode mass is plotted against time?

Electrolysis

A concentrated aqueous solution of sodium chloride is electrolysed using inert electrodes. Which row indicates what occurs in this electrolysis and the reason for it?

Electrolysis

When calcium carbonate is mixed with dilute hydrochloric acid, carbon dioxide gas is given off. Three arrangements of apparatus are shown. Which of the apparatus arrangements are appropriate, along with a stop-watch, for monitoring the rate of this reaction?

Rate of reaction

An energy profile diagram showing both the catalysed and uncatalysed reactions between $\text{N}_2$ and $\text{H}_2$ in the Haber process is displayed. What is the activation energy for forming $\text{NH}_3$ when a catalyst is present?

Rate of reaction

Which statement describes how magnesium atoms are converted into magnesium ions?

Ion and ionic bonds

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 changes occur?

Reversible reactions and equilibrium

Which row gives the correct descriptions of the solubilities of both ammonium sulfate and sodium carbonate in water?

Ion and ionic bonds

Since lead(II) chloride is an insoluble salt, Which two reagents are needed to prepare a pure sample of lead(II) chloride?

Preparation of salts

The Haber process is used to produce ammonia. Which catalyst is used in the Haber process?

Reversible reactions and equilibrium

Certain compounds that contain nitrogen are used as fertilisers. The table lists some compounds containing nitrogen, whether or not they are used as fertilisers and a reason for each. Which row is correct?

Fertilisers

Which element has an atom whose electronic configuration is the same as that of an atom of a strontium ion?

Atomic structure and the Periodic Table

Metals are elements that share many common properties because of the way they are structured. Which of the following statements about metals is correct?

Properties of metals

What occurs when a strip of silver is placed into aqueous copper(II) sulfate?

Reactivity series

Certain substances can be separated by means of paper chromatography. The diagram illustrates the outcome of running two mixtures in an appropriate solvent. Which spot has an $R_f$ value of $0.37$?

Chromatography

The four metals below, along with hydrogen, are shown in descending order of reactivity: potassium aluminium zinc hydrogen copper Which statement about these elements is correct?

Reactivity series

Iron is obtained from haematite in a blast furnace. Coke and limestone are put into the blast furnace. What does the limestone do?

Extraction of metals

Carbon dioxide, methane and oxygen are gases that take part in the carbon cycle. Which of these gases can contribute to global warming?

Air quality and climate

Two statements concerning the water in lakes are provided.

Water

A reaction takes place between chlorine and methane. Which row is the correct one?

Alkanes

Which statements about alkenes are correct?

Alkenes

X is a branched hydrocarbon in which the ratio of carbon atoms to hydrogen atoms is $1:2$. X has a relative molecular mass of $56$. What is X?

Alkenes

Each of the reactions shown below involves ethanol. 1. $\text{C}_2\text{H}_5\text{OH} + \text{O}_2 \rightarrow \text{CH}_3\text{COOH} + \text{H}_2\text{O}$ 2. $\text{C}_2\text{H}_5\text{OH} + \text{CH}_3\text{COOH} \rightarrow \text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O}$ 3. $\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2$ Which row gives the correct description of each reaction?

Alcohols

Ethanoic acid reacts with propanol. What is the ester called, and what is its structure?

Naming organic compounds

The diagram illustrates part of a polymer structure. Which type of polymer is shown?

Polymers

Petroleum (crude oil) is split into useful fractions by fractional distillation. The points on the fractionating column where fractions X and Y are taken off are shown. Which statement is correct?

Fuels

The diagram represents the repeat unit of a polymer. Which row correctly states the monomer and the kind of polymerisation used to produce this polymer?

Polymers

At room temperature and pressure, compound X exists as a crystalline solid. An aqueous solution of X is examined as follows. Test results: • Acidify with dilute nitric acid, then add aqueous barium nitrate: no observable change. • Add aqueous ammonia: a white precipitate forms, which dissolves in excess. What is a possible identity of X?

Identification of ions and gases

When aqueous sodium hydroxide is introduced into a solution, a white precipitate is produced that dissolves on adding excess sodium hydroxide. Which ion might be present in the solution?

Identification of ions and gases

Why does a balloon filled with helium gas get smaller when the temperature changes from $30\,^{\circ}\text{C}$ to $10\,^{\circ}\text{C}$?

Solids, liquids and gases

A diagram of an ion is shown. What can be inferred about the number of protons in this ion?

Atomic structure and the Periodic Table

The circuit diagram illustrates an experiment that uses a copper rod and a graphite rod. When the switch is closed, the bulb lights up because an electric current passes through the copper and the graphite. Which particles travel through these two solids?

Metallic bonding

In a titration experiment, an acid is put into a burette. The diagrams show part of the burette at the beginning of the titration and at the end-point. What volume of acid is used in the titration?

Acid–base titrations

Which material has the greatest melting point?

Giant covalent structures

Which statement gives the best description of ionic bonds?

Ion and ionic bonds

Which substances have at least one double bond?

Alkenes

Magnesium reacts with aqueous copper(II) sulfate to produce copper and aqueous magnesium sulfate. Which equation correctly represents this reaction?

Reactivity series

A sample of magnesium hydroxide has a mass of $4.63\,\text{g}$. How many moles of magnesium hydroxide are there?

The mole and the Avogadro constant

Which statement is true?

Elements, compounds and mixtures

Which sample has the greatest number of atoms?

The mole and the Avogadro constant

The equation represents iron being formed when iron(III) oxide is reduced. $\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2$. $80$ tonnes of iron(III) oxide gives $50$ tonnes of iron. Calculate the percentage yield.

The mole and the Avogadro constant

Aqueous copper(II) sulfate is electrolysed with copper electrodes. The current stays constant, and the anode is weighed at regular intervals of time. Which graph is obtained when the anode’s mass is plotted against time?

Electrolysis

The diagram illustrates the electrolysis of a mixture containing aqueous copper(II) nitrate, $\text{Cu(NO}_3)_2\text{(aq)}$, together with aqueous silver nitrate, $\text{AgNO}_3\text{(aq)}$. Electrodes X and Y are inert. Copper is above silver in the reactivity series. It follows that ……1…… is first deposited at electrode ……2……. Which words correctly fill gaps 1 and 2?

Electrolysis

When calcium carbonate is introduced to dilute hydrochloric acid, carbon dioxide gas is given off. Three apparatus arrangements are shown. Which arrangements of apparatus are suitable, together with a stop-watch, for monitoring the rate of this reaction?

Rate of reaction

The energy profile diagram for a chemical reaction is shown. What is the activation energy of the reaction?

Rate of reaction

Which statement explains the change from magnesium atoms into magnesium ions?

Ion and ionic bonds

Liquid water ionises only slightly. $\text{H}_2\text{O(l)} \rightleftharpoons \text{H}^+\text{(aq)} + \text{OH}^-\text{(aq)}$. The forward reaction absorbs heat. If the temperature of the water is raised, which changes occur?

Reversible reactions and equilibrium

Which of these salts can be made by precipitation?

Preparation of salts

In the reactivity series, silver is positioned below hydrogen. Which row shows the chemicals used and the method of separation used to obtain a pure sample of silver chloride?

Reactivity series

Ammonia is made by means of the Haber process. $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ The forward reaction gives out heat. Which one of the following statements about the Haber process is correct?

Reversible reactions and equilibrium

The table presents several facts about sulfur dioxide and sulfuric acid, together with comments on those facts. Which row is correct?

Oxides

Which element has atoms with the same electronic configuration as an atom of an ion of strontium?

Atomic structure and the Periodic Table

Metals possess high melting points. What causes this?

Metallic bonding

What occurs when a strip of silver is placed into aqueous copper(II) sulfate?

Reactivity series

Chromatography may be used to separate and identify the dyes in a mixture. Which statement is correct?

Chromatography

The five substances below are shown in order of decreasing reactivity: potassium → aluminium → zinc → hydrogen → copper Which of the following statements about these elements is correct?

Reactivity series

Aluminium is obtained from its ore by electrolysis. Which statement about the electrodes that are used is correct?

Electrolysis

Gas X is found in dry air and can help cause global warming. What is X?

Air quality and climate

During water purification, four processes are employed: • use of carbon • desalination • chlorination • filtration The aims, W, X, Y and Z, of these processes are given below. W: disinfection X: removal of solids Y: removal of dissolved salts Z: removal of tastes and odours What is the purpose of each process?

Water

When propane is combined with chlorine gas in ultraviolet light, substitution reactions take place. Which compound could be produced when propane and chlorine are combined in ultraviolet light?

Alkanes

The hydrocarbon $\text{CH}_3\text{CHCH}_2$ can take part in several chemical reactions. In which reaction is the carbon-to-carbon single bond broken?

Alkenes

Hydrocarbon compounds are able to make rings of carbon atoms as well as chains. The structures of two hydrocarbon rings, P and Q, are displayed. Which one of P and Q is unsaturated, and which one reacts with aqueous bromine?

Alkenes

Aqueous glucose is fermented using yeast at $37\,^{\circ}\text{C}$ without the presence of air. The principal organic product, X, is then separated by fractional distillation. Next, X is oxidised by heating under reflux with acidified potassium manganate(VII), producing the final product Y. Which substance is Y?

Carboxylic acids

The diagram illustrates the structure of a compound named ethanoic anhydride. $1\ \text{mol}$ of ethanoic anhydride reacts with water to produce only $2\ \text{mol}$ of a carboxylic acid. This carboxylic acid then reacts with ethanol to produce an ester. What number of moles of water react with $1\ \text{mol}$ of the ethanoic anhydride, and what is the ester structure?

Carboxylic acids

Combustion of polymers can lead to atmospheric pollution. Which polymer could release nitrogen oxides when it burns?

Polymers

Crude oil (petroleum) is separated into useful fractions by fractional distillation. The places in the fractionating column where fractions X and Y are obtained are shown. Which statement is correct?

Separation and purification

The diagram illustrates the repeat unit of a polymer. Which row correctly names the monomer and the type of polymerisation used to produce this polymer?

Polymers

Aqueous zinc chloride is tested using several reagents. Which observation is correct?

Identification of ions and gases

If aqueous sodium hydroxide is added to a solution and a white precipitate is produced that then dissolves in excess sodium hydroxide, which ion may be present in the solution?

Identification of ions and gases

A sample of gas takes up a volume of $2.0\,\text{dm}^3$ at room temperature and pressure. Which changes in the conditions would both make the gas occupy a smaller volume?

Solids, liquids and gases

A +3 ion has 20 electrons. Which element did it originate from?

Ion and ionic bonds

Which of the following statements is correct?

Elements, compounds and mixtures

Select from the compounds below to answer the questions. aluminium iodide ethanol glucose lead(IV) chloride lithium bromide magnesium carbonate methane potassium phosphate silver nitrate sodium sulfate sulfur dioxide Each compound may be used once, more than once, or not at all. Which compound:

Identification of ions and gases

The diagrams below show part of the structures of carbon dioxide and calcium carbide. The carbon dioxide molecules are displayed as O=C=O. Calcium carbide is represented as a lattice of Ca$^{2+}$ ions and C$_2^{2-}$ ions.

Simple molecules and covalent bonds

Copper is a metal. Explain why copper is able to conduct electricity.

Properties of metals

A drop of liquid bromine was put into a sealed glass jar. After some time, the bromine colour had spread to all parts of the jar. Explain this observation using the kinetic particle theory.

Group VII properties

Platinum and vanadium are each transition elements.

Transition elements

The table presents several properties of five alcohols.

Alcohols

Aluminium is obtained by means of the electrolysis of molten aluminium oxide.

Extraction of metals

When dilute nitric acid reacts with aqueous barium hydroxide: $2\text{HNO}_3(aq) + \text{Ba(OH)}_2(aq) \rightarrow \text{Ba(NO}_3)_2(aq) + 2\text{H}_2\text{O}(l)$

Acid–base titrations

Calcium is a metal belonging to Group II of the Periodic Table.

Reversible reactions and equilibrium

Select answers from the compounds listed below for these questions. aluminium sulfate ammonia calcium carbonate carbon dioxide chlorofluorocarbons copper(II) sulfate hydrogen chloride potassium nitrate sodium chloride A compound may be chosen once, more than once, or not used at all.

Elements, compounds and mixtures

Diagrams of chlorine and sodium chloride are shown here. In the chlorine diagram, the particles are Cl-Cl molecules. In the sodium chloride diagram, the particles form a lattice of alternating $\text{Na}^+$ and $\text{Cl}^-$ ions.

Electrolysis

A drop of black ink is added to the bottom of a beaker of water. After some time, the colour spreads through the water. Explain this observation using the kinetic particle theory.

Identification of ions and gases

Name one more naturally occurring substance in water that is neither a mineral salt nor a pollutant.

Group I properties

Give one additional reason why petroleum companies carry out cracking.

Alkenes

Methanoic acid and ethanoic acid belong to the group of weak acids.

Carboxylic acids

In a blast furnace, iron is obtained from iron ore by using coke (carbon) and limestone.

Extraction of metals

This question concerns several sulfur compounds.

Preparation of salts

Lead is a metal belonging to Group IV of the Periodic Table.

Reversible reactions and equilibrium

A student wants to identify the dyes in a dye mixture by separating them. The apparatus used by the student is shown below. The student also tests dyes A, B, C and D.

Chromatography

On heating, metal carbonates break down and release a gas that makes limewater go milky. A student studies how quickly four metal carbonates decompose using the apparatus shown. The student: - heats each metal carbonate separately with a Bunsen burner - records the time taken for the limewater to become milky. The results are displayed in the table.

Rate of reaction

A student receives dilute sulfuric acid labelled L. The concentration of L is found by titration. To measure and move $25.0\,\text{cm}^3$ of L into apparatus B, the student uses apparatus A. The diagrams display apparatus A and B. The student dilutes the $25.0\,\text{cm}^3$ portion of L to $500\,\text{cm}^3$ with distilled water in apparatus B. The resulting solution is M. The student then transfers $25.0\,\text{cm}^3$ of M into a conical flask and adds two drops of methyl orange indicator. Solution R is $0.100\,\text{mol dm}^{-3}$ aqueous sodium hydroxide, $\text{NaOH(aq)}$. R is delivered from a burette into the conical flask until the indicator alters colour and the end-point is reached.

Acid–base titrations

A student aims to electroplate a metal spoon with a coating of copper. Plan how the student should carry out the experiment.

Electrolysis

Compound Q is made up of two cations and one anion. The table below records the tests a student carries out on compound Q. Complete the table using the test results. Identify any gases produced in the tests.

Identification of ions and gases

A student is investigating how much heat is given out when ethanol burns. The diagram shows the apparatus the student uses.

Exothermic and endothermic reactions

A student examines two separate aqueous electrolytes with the apparatus illustrated.

Electrolysis

On heating, solid Group I nitrates break down and release a gas that will relight a glowing splint. A student investigates how quickly four Group I nitrates decompose. Each nitrate is heated separately with a Bunsen burner, and the student times how long it takes for a glowing splint to relight for each one.

Rate of reaction

A student is given solution K, which is aqueous sodium hydroxide, NaOH, and the concentration of K is found by titration.

Acid–base titrations

The sample is a mixture of copper(II) carbonate and carbon. Both substances are solids and are insoluble in water.

Separation and purification

A solid sample R contains two cations and one anion. The table lists the tests a student performs on R.

Identification of ions and gases

A student measures how the temperature increase changes when different masses of magnesium are added to dilute hydrochloric acid.

Exothermic and endothermic reactions