May/June 2012

In which species is the underlined atom lacking a full outer shell?

Chemical bonding

Titanium oxide, $\text{TiO}_2$, is used as a ‘whitener’ in toothpaste. It is produced from the ore iron(II) titanate, $\text{FeTiO}_3$. What change, if any, occurs in the oxidation number (oxidation state) of titanium during the reaction $\text{FeTiO}_3 \rightarrow \text{TiO}_2$?

Electrochemistry

The diagram illustrates a cell used in the production of aluminium. Which statement is not correct?

Electrochemistry

Aluminium chloride speeds up certain reactions by producing carbocations from chloroalkanes, as illustrated. $\text{RCl} + \text{AlCl}_3 \rightarrow \text{R}^+ + \text{AlCl}_4^-$ Which property allows this reaction to occur?

Chemical bonding

The Data Booklet may be needed for this question. A mineral was heated in a Bunsen flame until its mass no longer changed, and a colourless gas was released that made limewater go milky. After the residue had been cooled, it was added to aqueous hydrochloric acid. Vigorous effervescence occurred. Which mineral was it?

Group 2

The Data Booklet may be needed for this question. A mixture of aluminium powder and anhydrous barium nitrate is used as the propellant in certain fireworks. Only metal oxides and nitrogen are formed. What volume of nitrogen, measured under room conditions, is formed when $0.783\,\text{g}$ of anhydrous barium nitrate reacts with excess aluminium?

Atoms, molecules and stoichiometry

The oxides $\text{BaO}$, $\text{CaO}$, $\text{MgO}$ and $\text{SrO}$ each form alkaline solutions when they are added to water. Which oxide gives the saturated solution with the greatest $\text{pH}$?

Group 2

During the treatment of domestic water supplies, chlorine is introduced into the water to produce $\text{HClO}$. $\text{Cl}_2(\text{aq}) + \text{H}_2\text{O(l)} \rightarrow \text{H}^+(\text{aq}) + \text{Cl}^-(\text{aq}) + \text{HClO(aq)}$ The $\text{HClO}$ then reacts further, forming $\text{ClO}^-$ ions. $\text{HClO(aq)} + \text{H}_2\text{O(l)} \rightarrow \text{H}_3\text{O}^+(\text{aq}) + \text{ClO}^-(\text{aq})$ Both $\text{HClO}$ and $\text{ClO}^-$ destroy bacteria through oxidation. What is the overall change in oxidation number of chlorine when the $\text{ClO}^-$ ion is formed from aqueous chlorine?

Electrochemistry

What pattern is seen as you move down Group VII?

Group 17

In the two experiments described below, anhydrous potassium chloride is used and the results labelled X and Y are noted at the end of each one. Concentrated sulfuric acid is added to the potassium chloride, and the fumes given off are passed through aqueous potassium iodide solution – observation X. The potassium chloride is first dissolved in aqueous ammonia, and this solution is then mixed with aqueous silver nitrate – observation Y. What are observations X and Y?

Group 17

Carbon monoxide, $\text{CO}$, nitrogen monoxide, $\text{NO}$, and sulfur dioxide, $\text{SO}_2$, can all be found in the exhaust gases from a car engine. Which reaction involving these compounds takes place in the atmosphere?

Nitrogen and sulfur

Ammonia is produced by the Haber Process in an exothermic reaction. If the amount of catalyst is kept constant, which change would not cause an increase in the rate of the forward reaction?

Reaction kinetics

Fumaric acid may be changed into oxaloacetic acid through a two-stage route that uses the intermediate Q. $\text{HO}_2\text{CCH=CHCO}_2\text{H} \xrightarrow{\text{step 1}} Q \xrightarrow{\text{step 2}} \text{HO}_2\text{CCOCH}_2\text{CO}_2\text{H}$ In the laboratory, each stage can be carried out with just one reagent. What might Q be, and which reagent is needed for step 2?

Chemical bonding

Compound J is an organic compound that reacts with sodium, forming an organic ion carrying a charge of $-3$. When J reacts with $\text{NaOH(aq)}$, an organic ion with charge $-1$ is formed. What could the structural formula of J be?

Hydroxy compounds

The Data Booklet is needed for this question. A sample of ethyl propanoate is hydrolysed by heating it under reflux with aqueous sodium hydroxide. The two organic products formed in the hydrolysis are then separated, purified and weighed. As a percentage of the total mass of products collected, what is the mass percentage of each product?

Atoms, molecules and stoichiometry

Compound C is used in textile and leather processing. On gentle heating with a few drops of concentrated sulfuric acid, which starting material(s) produce compound C?

Organic synthesis

What is the number of isomeric esters with molecular formula $\text{C}_4\text{H}_8\text{O}_2$?

Carboxylic acids and derivatives

Which compound, when it reacts with hydrogen cyanide, gives a product that contains a chiral centre?

Carbonyl compounds

Which one of these compounds can be oxidised by acidified dichromate(VI) solution and also produces a positive result with Tollens’ reagent?

Carbonyl compounds

A halogen in an organic compound can be detected by heating the organic compound with aqueous silver nitrate. Which compound would form a precipitate most rapidly?

Halogen compounds

A reaction pathway diagram is shown. Which reaction is not represented by this profile?

Chemical energetics

When the ozone layer in the upper atmosphere is reduced, Earth’s natural shield against harmful ultraviolet radiation becomes weaker. Which compound would lead to the greatest depletion of the ozone layer?

Halogen compounds

The equation for a reaction is given below. $\text{H}_2(\text{g}) + \frac{1}{2}\text{O}_2(\text{g}) \rightarrow \text{H}_2\text{O}(\ell)\ ; \Delta H = x\ \text{kJ mol}^{-1}$ Which pair of statements is entirely correct for this reaction?

Chemical energetics

Which statement is not an accurate description of the polymer PVC?

Chemical bonding

The gas laws may be expressed by the ideal gas equation $pV = nRT$, with each symbol carrying its usual meaning. Which statements are correct?

States of matter

The Data Booklet is needed for this question. In which pair do both species contain the same number of unpaired $p$ electrons?

Atomic structure

Nitrogen and phosphorus are both placed in Group V of the Periodic Table. Phosphorus can form a chloride with the formula $\text{PCl}_5$. Why is it impossible for nitrogen to form $\text{NCl}_5$?

Chemical bonding

Ammonia and chlorine react in the gas phase. $8\text{NH}_3 + 3\text{Cl}_2 \rightarrow \text{N}_2 + 6\text{NH}_4\text{Cl}$ Which of the following statements is correct?

Nitrogen and sulfur

Which of the following statements are true for all three halogens, chlorine, bromine and iodine?

Group 17

During sulfuric acid manufacture, the reaction $\text{2SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightleftharpoons \text{2SO}_3\text{(g)}$ is normally carried out at $400\,^{\circ}\text{C}$ and $1\,\text{atm}$ pressure. In an industrial plant, the pressure is altered to $20\,\text{atm}$. What consequences would this change have?

Equilibria

What is invariably present in a carbon-carbon $\pi$ bond?

Chemical bonding

Several alcohols with the formula $\text{C}_4\text{H}_{10}\text{O}$ are oxidised separately. If $70\,\text{g}$ of these alcohols are used and the organic product is obtained in a $62\%$ yield, what mass of product can be produced?

Atoms, molecules and stoichiometry

The compound cis-hex-3-enal gives cut grass its distinctive smell. The human nose is especially sensitive to this compound and can detect $0.25$ parts per billion in air. Which reagents will react with cis-hex-3-enal?

Carbonyl compounds

Calcium has a second ionisation energy of $1150\ \text{kJ mol}^{-1}$. Which equation correctly shows this statement?

Atomic structure

How can a good yield of ethylamine be obtained from bromoethane as the starting material?

Nitrogen compounds

The following two conversions are given. $\text{NH}_4^+ \rightarrow \text{NH}_3$ $\text{C}_2\text{H}_4 \rightarrow \text{C}_2\text{H}_6$ What common feature is shared by these two conversions?

Atomic structure

The Data Booklet may be used for this question. The ideal gas equation summarises the gas laws. $\,pV = nRT$ A vessel contains $0.56\ \text{g}$ of ethene gas at a pressure of $102\ \text{kPa}$ and a temperature of $30\,^{\circ}\text{C}$. What is the volume of the vessel?

States of matter

Propanone has the molecular formula $\text{C}_3\text{H}_6\text{O}$. The enthalpy change of combustion of hydrogen is $-286\ \text{kJ mol}^{-1}$. The enthalpy change of combustion of carbon is $-394\ \text{kJ mol}^{-1}$. The enthalpy change of combustion of propanone is $-1786\ \text{kJ mol}^{-1}$. From this data, determine the enthalpy change of formation of propanone?

Chemical energetics

In which conditions is a gas most likely to act ideally?

States of matter

Initially, 2 moles of compound $P$ were introduced into a vessel. On heating, some of compound $P$ decomposed, and a dynamic equilibrium was set up among chemicals $P$, $Q$ and $R$. When equilibrium was reached, $x$ mol of $R$ were present and the total amount of substance present was $(2 + x)$. What is the equation for this equilibrium?

Equilibria

The molecular energy distribution curve shows how the energy of the molecules in a gas varies at room temperature. Which curve is correct for the same gas at a lower temperature?

Reaction kinetics

Which molecule has the greatest overall dipole?

Chemical bonding

In which substance is nitrogen found at its highest oxidation state?

Electrochemistry

Red lead oxide, $\text{Pb}_3\text{O}_4$, is used in metal priming paints. It can be prepared by heating PbO in air. $6\text{PbO(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Pb}_3\text{O}_4\text{(s)}$. Which two quantities are required to calculate the enthalpy change for this reaction?

Chemical energetics

Which gas occurs in car engine exhaust fumes in a far larger amount than any other gas?

Atoms, molecules and stoichiometry

Slaked lime, $\text{Ca(OH)}_2$, can be produced starting from limestone, $\text{CaCO}_3$. When limestone is heated in a lime kiln at $1000^\circ\text{C}$, it breaks down according to the equation below. reaction 1: $\text{CaCO}_3(s) \rightarrow \text{CaO}(s) + \text{CO}_2(g)$ Water is then added to calcium oxide, $\text{CaO}$, in the reaction shown below. reaction 2: $\text{CaO}(s) + \text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(s)$ What are the enthalpy changes of these reactions?

Chemical energetics

The period 4 elements gallium (Ga), germanium (Ge), arsenic (As) and selenium (Se) lie directly below aluminium, silicon, phosphorus and sulfur in the Periodic Table. Each period 4 element has properties similar to the period 3 element above it. Which of the period 4 elements produce oxides that dissolve in water to form an acid solution?

Chemical bonding

Chlorine has oxidation states in its compounds that extend from $-1$ up to $+7$. What reagent(s) and conditions are required to oxidise elemental chlorine to a compound in which chlorine has the $+5$ oxidation state?

Group 17

What is observed when a piece of magnesium ribbon is put into cold water?

Group 2

Sodium and sulfur combine to produce sodium sulfide, $\text{Na}_2\text{S}$. How does the atomic radius of sodium compare with that of sulfur, and how does the ionic radius of sodium compare with that of sulfur?

The Periodic Table: chemical periodicity

Which substance does not give off a poisonous gas when it is burnt in a limited supply of air?

Hydrocarbons

For which species are the numbers of protons, neutrons and electrons all unequal?

Atomic structure

A sample of propyl ethanoate is heated under reflux with aqueous sodium hydroxide so that hydrolysis takes place. The two organic products formed in the hydrolysis are then separated, purified and weighed. Of the total mass of products collected, what percentage by mass is represented by each product?

Atoms, molecules and stoichiometry

Which diagram shows the skeletal formula for 2-chloropentan-3-ol?

Chemical bonding

If 1-bromopropane is first reacted with reagent X and then with reagent Y, propanoic acid is formed. Which reagents are X and Y?

Organic synthesis

Isomers X and Y each react with HBr. A blend of X and Y is then treated with HBr. Which three structures are the three different possible products formed in this reaction?

Hydrocarbons

Oct-1-ene, $\text{CH}_3(\text{CH}_2)_5\text{CH}=\text{CH}_2$, undergoes thermal cracking. Which set of compounds W, X, Y and Z could be formed? $\text{W}: \text{CH}_2=\text{CH}_2$ $\text{X}: \text{CH}_3\text{CH}=\text{CH}_2$ $\text{Y}: \text{CH}_3\text{CH}_2\text{CH}_3$ $\text{Z}: \text{CH}_2=\text{CHCH}=\text{CH}_2$

Reaction kinetics

When phenacyl chloride, $\text{C}_6\text{H}_5\text{COCH}_2\text{Cl}$, reacts with aqueous NaOH, this substitution proceeds by an $\text{S}_\text{N}2$ mechanism. Which structure shows a species produced in the reaction?

Halogen compounds

When compound $X$ undergoes complete combustion, the products are carbon dioxide and water only. A portion of $X$ is combined with aqueous potassium dichromate and heated under reflux for one hour. The resulting mixture is then distilled, and the only organic product obtained is collected. The collected organic product reacts with sodium to produce hydrogen, but it does not react with 2,4-dinitrophenylhydrazine reagent and it does not react with ethanol in the presence of concentrated sulfuric acid to form an ester. What conclusion can be drawn from this information?

Hydroxy compounds

A compound $Y$ shows these characteristics. • At room temperature and atmospheric pressure, it is a liquid. • It is only partly miscible with water. • It does not produce steamy fumes with $\text{PCl}_5$. What might $Y$ be?

Hydroxy compounds

Coniine is the principal component of the poison known as ‘oil of hemlock’. Coniine may be prepared by allowing ammonia to react with a dibromo compound, $X$. $\text{NH}_3 + \text{C}_8\text{H}_{16}\text{Br}_2 \rightarrow \text{coniine} + 2\text{HBr}$ What is the name of compound $X$?

Halogen compounds

An industrial solvent that is widely used contains a blend of propanone, $\text{CH}_3\text{COCH}_3$, and pentyl ethanoate, $\text{CH}_3\text{CO}_2(\text{CH}_2)_4\text{CH}_3$. Which reagent would show no reaction with this industrial solvent?

Carbonyl compounds

What is the most probable shape of a hydrazine molecule, $\text{N}_2\text{H}_4$?

Chemical bonding

An organic compound will turn dilute acidified aqueous potassium manganate(VII) colourless when warmed, yet it will not turn bromine water colourless. What might the organic compound be?

Hydroxy compounds

Which of the following molecules and ions are regular trigonal planar in shape?

Chemical bonding

Ammonia and chlorine react in the gas phase. $8\text{NH}_3 + 3\text{Cl}_2 \rightarrow \text{N}_2 + 6\text{NH}_4\text{Cl}$ Which of the following statements are true?

Atoms, molecules and stoichiometry

Concentrated sulfuric acid acts as a strong acid when it reacts with water. $\text{H}_2\text{SO}_4(\ell) + \text{aq} \rightarrow \text{H}^+(\text{aq}) + \text{HSO}_4^-(\text{aq})$ The ion $\text{HSO}_4^-$ that is produced behaves as a weak acid. $\text{HSO}_4^-(\text{aq}) \rightleftharpoons \text{H}^+(\text{aq}) + \text{SO}_4^{2-}(\text{aq})$ Which of the following statements are correct for $1.0\,\text{mol dm}^{-3}$ sulfuric acid?

Equilibria

Silver chloride dissolves in aqueous ammonia. What occurs during this process?

Equilibria

If HCl is compared with HBr, the bond ……X…… in the HBr molecule is ……Y…… . Which pair of words correctly completes the sentence above?

Chemical bonding

Which of the following statements about the Haber process used to manufacture ammonia are true?

Equilibria

Which compounds can be produced from propene in a single reaction?

Hydrocarbons

What do a pair of optical isomers have in common?

Chemical bonding

Which statements concerning the photochemical chlorination of ethane are correct?

Reaction kinetics

In which species does the underlined atom have an outer shell that is not full?

Chemical bonding

The compound illustrated is a hormone made during pregnancy that inhibits ovulation. Which reagents would produce positive tests with this compound?

An introduction to AS Level organic chemistry

Which solid has more than one type of bonding?

Chemical bonding

The Data Booklet is needed for this question. The gas laws may be represented by the ideal gas equation, $pV = nRT$. A mass of $0.96\,\text{g}$ of oxygen gas is held in a glass vessel with volume $7000\,\text{cm}^3$ at a temperature of $30^\circ\text{C}$. Determine the pressure inside the vessel.

States of matter

Initially, two moles of compound P were put into a vessel. The vessel was then heated, causing compound P to decompose partly into Q and R. A dynamic equilibrium was set up among chemicals P, Q and R. When equilibrium was reached, there were $x$ moles of R present, and the total amount of substance present was $(2 + \frac{x}{2})$ moles. What is the equation for this equilibrium reaction?

Equilibria

Aluminium has a third ionisation energy of $2740\,\text{kJ mol}^{-1}$. Which option gives the correct representation of this statement?

Atomic structure

Methanol is produced by reacting carbon dioxide with hydrogen. $\text{CO}_2\text{(g)} + 3\text{H}_2\text{(g)} \rightleftharpoons \text{CH}_3\text{OH(g)} + \text{H}_2\text{O(g)} \quad \Delta H = -49\,\text{kJ mol}^{-1}$. Which change would raise the equilibrium yield of methanol in this process?

Equilibria

Ammonia is produced by the Haber Process in an exothermic reaction. If the amount of catalyst is kept constant, which change will not cause the rate of the forward reaction to increase?

Reaction kinetics

Titanium oxide, $\text{TiO}_2$, is used as a ‘whitener’ in toothpaste. It is made from the ore iron(II) titanate, $\text{FeTiO}_3$. What, if any, change takes place in the oxidation number (oxidation state) of titanium in the reaction $\text{FeTiO}_3 \rightarrow \text{TiO}_2$?

Electrochemistry

A vessel initially contained two moles of compound $P$. When heated, compound $P$ decomposed partially. A dynamic equilibrium involving chemicals $P$, $Q$ and $R$ was then reached. At equilibrium, $x$ mol of $R$ were present, and the overall amount of substance present was $(2 + x)$ mol. What equation represents this equilibrium?

Equilibria

A mineral was heated in a Bunsen flame until it had reached constant mass, and a colourless gas that caused lime water to turn milky was given off. The solid left behind was then cooled and added to aqueous hydrochloric acid. Strong effervescence was observed. What was the mineral?

Group 2

Aluminium chloride catalyses some reactions by producing carbocations from chloroalkanes, as shown here. $\text{RCl} + \text{AlCl}_3 \rightarrow \text{R}^+ + \text{AlCl}_4^-$ Which property allows this reaction to occur?

Chemical bonding

When BaO, CaO, MgO and SrO are added to water, each of these oxides forms an alkaline solution. Which oxide forms the saturated solution with the greatest pH?

Equilibria

A reaction between aluminium powder and anhydrous barium nitrate is employed as the propellant in some fireworks. The only products formed are metal oxides and nitrogen. What volume of nitrogen, measured at room conditions, is formed when $0.783\,\text{g}$ of anhydrous barium nitrate reacts with excess aluminium?

Atoms, molecules and stoichiometry

Two experiments using anhydrous potassium chloride are performed, and the end results are recorded as observations X and Y. First, concentrated sulfuric acid is added to the potassium chloride, and the gases given off are passed into aqueous potassium iodide solution - observation X. Second, the potassium chloride is dissolved in aqueous ammonia, and this mixture is then added to aqueous silver nitrate - observation Y. What are observations X and Y?

Chemical bonding

During the disinfection of domestic water supplies, chlorine is introduced into the water to produce HClO. $\text{Cl}_2(aq) + \text{H}_2\text{O}(l) \rightarrow \text{H}^+(aq) + \text{Cl}^-(aq) + \text{HClO}(aq)$ The HClO then goes on to form $\text{ClO}^-$ ions. $\text{HClO}(aq) + \text{H}_2\text{O}(l) \rightarrow \text{H}_3\text{O}^+(aq) + \text{ClO}^-(aq)$ Both HClO and $\text{ClO}^-$ destroy bacteria through oxidation. What is the net change in oxidation number of chlorine when the $\text{ClO}^-$ ion is formed from aqueous chlorine?

Electrochemistry

What pattern is seen as you go down Group VII?

Group 17

Fumaric acid may be converted into oxaloacetic acid by a two-stage route that passes through the intermediate Q. $\text{HO}_2\text{CCH=CHCO}_2\text{H} \xrightarrow{\text{step 1}} Q \xrightarrow{\text{step 2}} \text{HO}_2\text{CCOCH}_2\text{CO}_2\text{H}$ In the laboratory, either of these stages can be carried out with a single reagent. What might the intermediate Q be, and which reagent could be used for step 2?

Hydroxy compounds

In which species does the underlined atom possess an incomplete outer shell?

Chemical bonding

In the exhaust fumes from a car engine, carbon monoxide, CO, nitrogen monoxide, NO, and sulfur dioxide, $\text{SO}_2$, may all be found. Which atmospheric reaction involving these compounds takes place?

Nitrogen and sulfur

Organic compound J reacts with sodium, forming an organic ion with charge $-3$. J also reacts with $\text{NaOH(aq)}$ to form an organic ion with charge $-1$. What might be the structural formula of J?

Atomic structure

Compound C is used in textile and leather processing. On gentle heating with a few drops of concentrated sulfuric acid, which starting material(s) produce compound C?

Organic synthesis

How many isomeric esters have the molecular formula $\text{C}_4\text{H}_8\text{O}_2$?

Carboxylic acids and derivatives

A sample of ethyl propanoate is hydrolysed by heating under reflux with aqueous sodium hydroxide. The two organic products formed by the hydrolysis are then separated, purified and weighed. What percentage by mass does each product represent of the total mass of products obtained?

Atoms, molecules and stoichiometry

The compounds below are identified as W, X, Y and Z: $\text{W: CH}_3\text{COCH}_2\text{CH}_2\text{OH}$ $\text{X: CH}_3\text{COCH}_2\text{CHO}$ $\text{Y: CH}_3\text{CH(OH)CH}_2\text{CH}_3$ $\text{Z: CH}_3\text{CH}_2\text{CH}_2\text{CHO}$ Which one or more of these compounds may be oxidised by acidified dichromate(VI) solution and also gives a positive result with Tollens’ reagent?

Electrochemistry

Which compound, when it reacts with hydrogen cyanide, forms a compound containing a chiral centre?

Carbonyl compounds

When the ozone layer in the upper atmosphere is depleted, Earth’s natural shield against harmful ultraviolet radiation is weakened. Which compound would lead to the greatest depletion of the ozone layer?

Halogen compounds

A halogen in an organic compound can be detected by heating the organic compound with aqueous silver nitrate. Which compound would form a precipitate most rapidly?

Reaction kinetics

A reaction pathway diagram is shown. Which reaction does not show this kind of profile?

Chemical energetics

For calcium, the second ionisation energy is $1150\,\text{kJ mol}^{-1}$. Which equation shows this statement correctly?

Atomic structure

Which statement does not accurately describe the polymer PVC?

Chemical bonding

Nitrogen and phosphorus are both placed in Group V of the Periodic Table. Phosphorus makes a chloride with the formula $\text{PCl}_5$. Why is it impossible for nitrogen to form $\text{NCl}_5$?

Nitrogen and sulfur

The Data Booklet may be needed for this question. Which pair contains species that each have the same number of unpaired $p$ electrons?

Atomic structure

The gas laws may be expressed by the ideal gas equation. $pV = nRT$ in which each symbol has its normal meaning. Which statements are correct?

States of matter

Which of the following statements is true for all three halogens, chlorine, bromine and iodine?

Group 17

During sulfuric acid manufacture, the reaction $\text{2SO}_2(g) + \text{O}_2(g) \rightleftharpoons \text{2SO}_3(g)$ is usually carried out at $400\,^{\circ}\text{C}$ and $1\ \text{atm}$ pressure. At one industrial plant, the pressure is changed to $20\ \text{atm}$. What consequences will result from this change?

Equilibria

Ammonia and chlorine react in the gas phase. $\text{8NH}_3 + \text{3Cl}_2 \rightarrow \text{N}_2 + \text{6NH}_4\text{Cl}$. Which of the following statements are correct?

Atoms, molecules and stoichiometry

Several alcohols with the formula $\text{C}_4\text{H}_{10}\text{O}$ are oxidised individually. If $70\ \text{g}$ of the alcohols gives a $62\%$ yield of organic product, what mass of product could be obtained?

Atoms, molecules and stoichiometry

What is invariably present in a carbon-carbon $\pi$ bond?

Chemical bonding

How is a high yield of ethylamine obtained from bromoethane as the starting material?

Organic synthesis

A reaction equation is given below. $\text{H}_2(g) + \tfrac{1}{2}\text{O}_2(g) \rightarrow \text{H}_2\text{O}(l) ;\ \Delta H = x\,\text{kJ mol}^{-1}$ Which pair of statements is entirely correct for this reaction?

Chemical energetics

The compound cis-hex-3-enal is the substance that gives cut grass its distinctive smell. The human nose is especially sensitive to this compound, and can detect $0.25$ parts per billion in air. Which reagents react with cis-hex-3-enal?

Carbonyl compounds

The molecular formula of propanone is $\text{C}_3\text{H}_6\text{O}$. The enthalpy change of combustion of hydrogen is $-286\,\text{kJ mol}^{-1}$. The enthalpy change of combustion of carbon is $-394\,\text{kJ mol}^{-1}$. The enthalpy change of combustion of propanone is $-1786\,\text{kJ mol}^{-1}$. From this data, determine the enthalpy change of formation of propanone.

Chemical energetics

The two conversions shown here are as follows. $\text{NH}_4^{+} \rightarrow \text{NH}_3$ $\text{C}_2\text{H}_4 \rightarrow \text{C}_2\text{H}_6$ What common characteristic is shared by these two conversions?

Hydrocarbons

The ideal gas equation is used to summarise the gas laws. $pV = nRT$ A vessel contains $0.56\,\text{g}$ of ethene gas at a pressure of $102\,\text{kPa}$ and a temperature of $30^{\circ}\text{C}$. Calculate the volume of the vessel.

States of matter

Under what conditions is a gas most likely to show ideal behaviour?

States of matter

The diagram depicts a cell used for the production of aluminium. Which statement is not correct?

Electrochemistry