May/June 2011

Which equation shows the second ionisation energy of an element X?

Atomic structure

Three substances, R, S and T, are described by the physical properties shown. Which substances could R, S and T be?

Chemical bonding

For which change would van der Waals’ forces be the only intermolecular forces that must be overcome?

States of matter

Hydrazine, $\text{N}_2\text{H}_4$, is commonly used as a rocket fuel because it reacts with oxygen in the way shown, giving ‘environmentally friendly’ gases. $\text{N}_2\text{H}_4\text{(l)} + \text{O}_2\text{(g)} \rightarrow \text{N}_2\text{(g)} + 2\text{H}_2\text{O(g)} \quad \Delta H = -534 \text{ kJ mol}^{-1}$. Even though hydrazine is used as a rocket fuel, it does not burn spontaneously in oxygen. Which statement gives the reason hydrazine does not burn spontaneously?

Reaction kinetics

0.02 mol of aluminium is burnt in oxygen, and the product is then treated with 2.00 mol dm$^{-3}$ hydrochloric acid. What minimum volume of acid is needed for the reaction to go to completion?

Atoms, molecules and stoichiometry

Steam is led over heated magnesium to form compound X and hydrogen. Which of the following is not a property of compound X?

Chemical bonding

X, Y and Z are three different halogens. The table presents the outcomes of nine experiments in which aqueous solutions of $\text{X}_2$, $\text{Y}_2$ and $\text{Z}_2$ were each added separately to aqueous solutions containing $\text{X}^-$, $\text{Y}^-$ and $\text{Z}^-$. Which row in the table below lists the ions $\text{X}^-$, $\text{Y}^-$ and $\text{Z}^-$ in descending order of reducing agent strength?

Electrochemistry

A student noted the outcomes when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid. The results are shown in the table. Which deduction can be made from these observations?

Electrochemistry

Ammonium nitrate, $\text{NH}_4\text{NO}_3$, is produced on a large scale for use as a fertiliser. Which statement about ammonium nitrate fertiliser is incorrect?

Atoms, molecules and stoichiometry

Nitrogen monoxide, NO, is a primary pollutant formed by petrol engines and present in their exhaust gases. Which reaction takes place in a catalytic converter and lowers the emission of nitrogen monoxide?

Nitrogen and sulfur

In the reaction sequence shown below, an alkane is changed into a carboxylic acid over several steps. $\text{C}_{10}\text{H}_{22} \xrightarrow{\text{stage 1}} \text{C}_2\text{H}_4 \xrightarrow{\text{stage 2 (catalytic hydration)}} \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{stage 3}} \text{CH}_3\text{CO}_2\text{H}$. Which processes take place at stage 1 and at stage 3?

Organic synthesis

In waterlogged soils, such as those used for rice growing, the oxygen level is low. In these soils, anaerobic bacteria lead to nitrogen being lost from the soil, as represented by the sequence below. $\text{NO}_3^-\text{(aq)} \xrightarrow{A} \text{NO}_2^-\text{(aq)} \xrightarrow{B} \text{NO(g)} \xrightarrow{C} \text{N}_2\text{O(g)} \xrightarrow{D} \text{N}_2\text{(g)}$ In which step does the change in oxidation number (oxidation state) of nitrogen differ from the changes in the other steps?

Electrochemistry

Acrylic acid is made from propene, a gaseous product from oil refineries. Which statement about acrylic acid is incorrect?

Carboxylic acids and derivatives

Butanedioic acid is present in amber, algae, lichens, sugar cane and beets. It can be prepared in two stages from $\text{BrCH}_2\text{CH}_2\text{Br}$. $\text{BrCH}_2\text{CH}_2\text{Br} \xrightarrow{\text{step 1}} X \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH}_2\text{CH}_2\text{CO}_2\text{H}$. Which reagents could be used to carry out this synthesis?

Organic synthesis

The formula $\text{CH}_3$ may stand for an anion, a cation, or a free radical. A species with molecular formula $\text{CH}_3$ can behave as an electrophile, a free radical, or a nucleophile, depending on how many outer shell electrons are on the central carbon atom. How many outer shell electrons are needed for $\text{CH}_3$ to behave in each of these ways?

Chemical bonding

Pentanol, $\text{C}_5\text{H}_{11}\text{OH}$, has four structural isomers that are primary alcohols. Of these primary alcohols, how many contain a chiral carbon atom?

Hydroxy compounds

The diagram illustrates the molecular structure of the naturally occurring molecule cholesterol. Student X said that all seventeen carbon atoms in the four rings are in one plane. Student Y said that this molecule shows $cis$-$trans$ isomerism about the $\text{C} = \text{C}$ double bond. Which students are correct?

An introduction to AS Level organic chemistry

Which isomer of $\text{C}_6\text{H}_{13}\text{OH}$ produces the largest number of distinct alkenes when it is dehydrated?

Hydroxy compounds

Compound X makes warm acidified sodium dichromate(VI) change from orange to green. $1$ mol of X reacts with $2$ mol of $\text{HCN}$ in the presence of $\text{KCN}$. What could X be?

Carbonyl compounds

Which formula shows an ester that produces sodium ethanoate when it is hydrolysed with aqueous sodium hydroxide?

Carboxylic acids and derivatives

Compound Y is warmed with acidified potassium dichromate(VI). The organic product formed then produces an orange precipitate with $2,4$-dinitrophenylhydrazine reagent, but it does not produce a silver mirror with Tollens’ reagent. What is Y?

Hydroxy compounds

Aldehydes and ketones are carbonyl compounds. Which of these react with $\text{NaBH}_4$ and also react with Fehling’s reagent?

Carbonyl compounds

In the extraction of aluminium by electrolysis of molten aluminium oxide, what is the purpose of adding cryolite to the aluminium oxide?

Electrochemistry

In a primary alcohol, the functional group is $-\text{CH}_2\text{OH}$. Which reagent can react with a primary alcohol, under suitable conditions, to produce an organic product containing the same number of oxygen atoms as the alcohol?

Hydroxy compounds

Which statements are correct under the Brønsted-Lowry theory of acids and bases?

Equilibria

Which characteristics describe the structure of metallic copper?

Chemical bonding

Zinc and hydrochloric acid react as shown in the equation: $\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2$. Which statements are correct? [All volumes are measured at room conditions.]

Atoms, molecules and stoichiometry

Which of the following statements are correct?

Atoms, molecules and stoichiometry

Which oxides will react with water to form a solution whose pH is $10$ or above?

Equilibria

The element astatine is located beneath iodine in Group VII of the Periodic Table. What properties would astatine have?

Group 17

Which statements about the ammonium ion are correct?

Nitrogen compounds

Which alkenes, when treated with steam at $600\,\text{K}$ and $6 \times 10^6\,\text{Pa}$ pressure in the presence of a phosphoric acid catalyst, may form an alcohol that contains a chiral carbon atom?

Hydrocarbons

Bromoethane undergoes every conversion shown here. Which of these conversions are nucleophilic substitution reactions?

Chemical bonding

The diagrams show different Boltzmann distributions. In diagram 1, one of the curves, P or Q, represents the higher temperature than the other curve. In diagram 2, one of the lines, X or Y, shows the activation energy for a catalysed reaction, while the other line shows the activation energy for the same reaction when it is uncatalysed. Which combination identifies the correct curve and line?

Reaction kinetics

Sorbitol is an artificial sweetener that is used to sweeten chocolate and is suitable for diabetics. Which functional groups may be formed when this molecule is oxidised under suitable conditions?

Carbonyl compounds

Which factor accounts for the decrease in the first ionisation energies of the Group I elements as the sequence goes from lithium to sodium to potassium to rubidium?

The Periodic Table: chemical periodicity

In the diagram, curve X was produced by monitoring the decomposition of $100\,\text{cm}^3$ of $1.0\,\text{mol dm}^{-3}$ hydrogen peroxide, with manganese(IV) oxide acting as the catalyst. Which change to the starting experimental conditions would result in curve Y?

Reaction kinetics

In the previous century, the Haber process was sometimes carried out at pressures of $1000\,\text{atm}$ and above. At present, it is usually carried out at pressures below $100\,\text{atm}$. What explains this change?

Equilibria

The equation given here shows gaseous atoms of non-metal X and hydrogen combining to produce gaseous $\text{X}_2\text{H}_6$ molecules. $2\text{X(g)} + 6\text{H(g)} \rightarrow \text{X}_2\text{H}_6\text{(g)} \qquad \Delta H = -2775\,\text{kJ mol}^{-1}$ The bond energy for an X-H bond is $395\,\text{kJ mol}^{-1}$. Calculate the bond energy of an X-X bond.

Chemical energetics

50 cm$^3$ of 2.50 mol dm$^{-3}$ hydrochloric acid was put into a polystyrene beaker with negligible heat capacity. The temperature was measured and then 50 cm$^3$ of 2.50 mol dm$^{-3}$ NaOH, initially at the same temperature, was rapidly added while stirring. The temperature increased by 17 ^{\circ}C. The final solution can be taken to have a specific heat capacity of 4.2 J g$^{-1}$ K$^{-1}$. What is an approximate value for the molar enthalpy change of neutralisation of hydrochloric acid and sodium hydroxide from this experiment?

Chemical energetics

Helium, $\text{He}$, is the second element in the Periodic Table. Tritium is the isotope of hydrogen $^3_1\text{H}$. What is the same between an atom of $^4_2\text{He}$ and an atom of $^3_1\text{H}$?

Atomic structure

Tanzanite is a gemstone used in jewellery. It is a hydrated calcium aluminium silicate mineral with chemical formula $\text{Ca}_2\text{Al}_x\text{Si}_y\text{O}_{12}(\text{OH})_6\cdot2\text{H}_2\text{O}$. The $M_r$ of tanzanite is $571.5$. Its percentage composition by mass is $14.04\%$ calcium, $14.17\%$ aluminium, $14.75\%$ silicon, $54.59\%$ oxygen and $2.45\%$ hydrogen. $(A_r$ values: H = $1.0$, O = $16.0$, Al = $27.0$, Si = $28.1$, Ca = $40.1)$ Determine the values of $x$ and $y$.

Atoms, molecules and stoichiometry

$0.144\text{ g}$ of an aluminium compound X is reacted with excess water, producing a gas. This gas then burns completely in $\text{O}_2$ to give $\text{H}_2\text{O}$ and only $72\text{ cm}^3$ of $\text{CO}_2$. The volume of $\text{CO}_2$ was recorded at room temperature and pressure. What could be the formula of X? [$\text{C} = 12.0$, $\text{Al} = 27.0$; $1$ mole of any gas occupies $24\text{ dm}^3$ at room temperature and pressure]

Atoms, molecules and stoichiometry

The Data Booklet may be needed for this question. Which element is likely to have an electronegativity close to that of aluminium?

Chemical bonding

In $1999$, researchers in the USA thought that they had discovered a new element and suggested that it had this electronic configuration. $[\text{Rn}]\ 5f^{14}6d^{10}7s^27p^6$ In which Group of the Periodic Table would you expect this element to be in?

The Periodic Table: chemical periodicity

The highest oxides of the elements from sodium to chlorine are each added separately to water. Which diagram shows the pH of the mixtures formed most accurately?

The Periodic Table: chemical periodicity

The diagram illustrates the first ionisation energies for $11$ elements in a row. What type of elements are represented by X and Y?

The Periodic Table: chemical periodicity

Why is aluminium oxide soluble in sodium hydroxide solution?

The Periodic Table: chemical periodicity

Concentrated sulfuric acid may act both as a strong acid and as an oxidising agent. For which compound does concentrated sulfuric acid react in this manner?

Electrochemistry

In the Contact process, what type of gaseous product is formed, and what catalyst is used?

Equilibria

In which compound do two different elements have the same oxidation state?

Electrochemistry

Which diagram shows the bonding in the ammonium ion, $\text{NH}_4^+$, correctly?

Chemical bonding

Which reagent produces the same observable result when tested with propanal and propan-2-ol?

Hydroxy compounds

Which halogenoalkane reacts by an $S_N1$ mechanism and forms a yellow precipitate when $\text{AgNO}_3\text{(aq)}$ is added?

Halogen compounds

Which reaction would produce 2-chloropropane in the highest yield?

Halogen compounds

Cracking an alkane, $X$, gives methane, ethene and propene as the products. The mole fraction of ethene in the products is $0.5$. What is the identity of $X$?

Atoms, molecules and stoichiometry

Which compound is incapable of cis-trans isomerism?

Chemical bonding

Which formulae indicate that propanone and propanal are different compounds?

Carbonyl compounds

How many isomers having the formula $\text{C}_5\text{H}_{10}$ possess structures that contain $\pi$ bonding?

Hydrocarbons

$1,1$-dichloropropane reacts with aqueous sodium hydroxide through a sequence of steps to produce propanal. $\text{CH}_3\text{CH}_2\text{CHCl}_2 \xrightarrow{\text{NaOH(aq)}} \text{CH}_3\text{CH}_2\text{CHO}$ Which term is used to describe the first stage of this reaction?

Halogen compounds

Which empirical formula is shown by the organic acid formed when acid in the stomach hydrolyses the ester $\text{CH}_3\text{CH}_2\text{CH}_2\text{CO}_2\text{CH}_3$, the substance that gives apples their aroma?

Atoms, molecules and stoichiometry

To answer this, consider how $\text{KMnO}_4$ reacts with different functional groups under the conditions given. The diagram depicts the structure of the naturally found molecule cholesterol. Cholesterol is then treated separately with cold, dilute acidified $\text{KMnO}_4$, and with hot, concentrated acidified $\text{KMnO}_4$. What change occurs in the number of chiral carbon atoms in the molecule in each reaction?

Hydrocarbons

Aluminium is the most plentiful metal in the Earth’s crust. Aluminium is obtained by electrolysing aluminium oxide dissolved in molten cryolite. What material is used to make each electrode in this electrolysis?

Electrochemistry

Which reaction would not produce ethanoic acid as a product?

Carboxylic acids and derivatives

A solid sample of calcium carbonate is placed into $100\ \text{cm}^3$ of dilute hydrochloric acid, and the reaction rate is measured. A second $100\ \text{cm}^3$ portion of the acid is then mixed with $100\ \text{cm}^3$ of distilled water, and the experiment is repeated under identical conditions. Why does adding water lower the rate of the reaction?

Reaction kinetics

If a sample of gas is compressed at constant temperature from $1500\ \text{kPa}$ to $6000\ \text{kPa}$, its volume changes from $76.0\ \text{cm}^3$ to $20.5\ \text{cm}^3$. Which of the following statements could explain this behaviour?

States of matter

Which equations are valid for an ideal gas? [$p$ = pressure, $V$ = volume, $M$ = molar mass, $\rho$ = density, $c$ = concentration, $R$ = gas constant, $T$ = temperature]

States of matter

What occurs when a hydrogen bond forms between two molecules?

Chemical bonding

If the yellow liquid $\text{NCl}_3(l)$ is added to aqueous sodium hydroxide and stirred, the reaction that takes place can be shown by the following equation. $2\text{NCl}_3(l) + 6\text{NaOH}(aq) \rightarrow \text{N}_2(g) + 3\text{NaCl}(aq) + 3\text{NaOCl}(aq) + 3\text{H}_2\text{O}(l)$ What outcome will this reaction produce?

Electrochemistry

A pollutant oxide $Y$ is produced in a car engine, and it contains the non-metal element $X$. In the atmosphere, $Y$ undergoes further oxidation to form $Z$. During this additional oxidation, $1$ mol of $Y$ reacts with $0.5$ mol of gaseous oxygen. $X$ may be nitrogen or sulfur. Which of the following statements about $X$, $Y$ and $Z$ can be true?

Atoms, molecules and stoichiometry

Which compounds are formed from ethene in one reaction?

Hydrocarbons

Which of the compounds, when heated under reflux with an excess of hot acidified potassium dichromate(VI), form a product containing a chiral centre?

Hydroxy compounds

For the reaction of an aldehyde with $\text{HCN}$, with $\text{NaCN}$ as the catalyst, which of the following statements about the reaction mechanism are correct?

Carbonyl compounds

The esterification reaction $\text{ethanol} + \text{ethanoic acid} \rightleftharpoons \text{ethyl ethanoate} + \text{water}$ is at equilibrium. The forward reaction is exothermic. In what way can the value of the equilibrium constant $K_c$ be increased?

Equilibria

An organic compound, $X$, reacts with an excess of calcium metal to form a salt whose empirical formula is $\text{CaC}_4\text{H}_6\text{O}_4$. Which compound could $X$ be?

Carboxylic acids and derivatives

Ammonia is produced on a large scale by means of the Haber process. In one specific plant, a temperature of $400\,^{\circ}\text{C}$ and a pressure of $250\,\text{atm}$ are applied together with an iron catalyst. $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \qquad \Delta H^{\circ} = -92\,\text{kJ mol}^{-1}$ What change could make the greatest contribution to a higher equilibrium yield of ammonia?

Equilibria

The Boltzmann distribution for a gas at constant temperature is illustrated below. If the gas temperature is lowered by $10\,^{\circ}\text{C}$, the shape of the graph alters. What happens to the values of $n$ at the points labelled $X$, $Y$ and $Z$?

Reaction kinetics

Titanium is found in nature as the mineral rutile, $\text{TiO}_2$. One way to extract titanium is to heat the rutile with carbon so that reduction occurs. $\text{TiO}_2(s) + 2\text{C}(s) \rightarrow \text{Ti}(s) + 2\text{CO}(g)$ The standard enthalpy changes of formation of $\text{TiO}_2(s)$ and $\text{CO}(g)$ are $-940\,\text{kJ mol}^{-1}$ and $-110\,\text{kJ mol}^{-1}$ respectively. Determine the standard enthalpy change for this reaction.

Chemical energetics

Which reaction has an enthalpy change that is the same as the standard enthalpy change of formation of propane?

Chemical energetics

When compound X was changed into compound Z, the reaction was observed to pass through compound Y, and Y could be isolated. The sequence of stages was as follows. $X \rightarrow Y ; \Delta H$ positive $Y \rightarrow Z ; \Delta H$ negative Which reaction profile is consistent with these results?

Chemical energetics

Which equation shows the second ionisation energy of an element X?

Atomic structure

In which change would it be necessary to overcome only van der Waals’ forces?

States of matter

Hydrazine, $\text{N}_2\text{H}_4$, is used extensively as a rocket fuel because it reacts with oxygen in the way shown, forming ‘environmentally friendly’ gases. $\text{N}_2\text{H}_4(l) + \text{O}_2(g) \rightarrow \text{N}_2(g) + 2\text{H}_2\text{O}(g) \quad \Delta H = -534\,\text{kJ mol}^{-1}$ Even though hydrazine is employed as a rocket fuel, it does not ignite of its own accord in oxygen. Which statement accounts for why hydrazine does not burn spontaneously?

Reaction kinetics

If $0.02\,\text{mol}$ of aluminium is burned in oxygen, the product is then allowed to react with $2.00\,\text{mol dm}^{-3}$ hydrochloric acid. What minimum volume of acid is needed for complete reaction?

Atoms, molecules and stoichiometry

The physical properties of three substances, R, S and T, are given below. R: $mp = 801^\f$, $bp = 1413^\f$, electrical conductivity in the solid state: poor S: $mp = 2852^\f$, $bp = 3600^\f$, electrical conductivity in the solid state: poor T: $mp = 3550^\f$, $bp = 4827^\f$, electrical conductivity in the solid state: good Which substances could R, S and T be?

Chemical bonding

Steam is reacted with heated magnesium to produce compound X and hydrogen. Which of the following is not a property of compound X?

Group 2

Petrol engines give rise to the primary pollutant nitrogen monoxide, $\text{NO}$, which is carried in exhaust gases. Which reaction in a catalytic converter lowers nitrogen monoxide emission?

Nitrogen and sulfur

X, Y and Z are three different halogens. The table presents the outcomes of nine experiments in which aqueous solutions of $\text{X}_2$, $\text{Y}_2$ and $\text{Z}_2$ were added separately to separate aqueous solutions containing $\text{X}^-$, $\text{Y}^-$ and $\text{Z}^-$ ions. Which row in the table below lists the ions $\text{X}^-$, $\text{Y}^-$ and $\text{Z}^-$ in descending order of their reducing power?

Electrochemistry

A student watched what happened when sodium chloride and sodium iodide were reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid. The observations are shown in the table. Which conclusion can be drawn from these observations?

Group 17

Ammonium nitrate, $\text{NH}_4\text{NO}_3$, is produced on a large scale for use in fertiliser. Which statement about ammonium nitrate fertiliser is incorrect?

Nitrogen and sulfur

Butanedioic acid is found in amber, algae, lichens, sugar cane and beets. It can be prepared in two stages starting from 1,2-dibromoethane. $\text{BrCH}_2\text{CH}_2\text{Br} \xrightarrow{\text{step 1}} X \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH}_2\text{CH}_2\text{CO}_2\text{H}$ Which reagents could be used for this synthesis?

Atoms, molecules and stoichiometry

Which factor accounts for the decrease in the first ionisation energies of the Group I elements from lithium to sodium to potassium to rubidium?

The Periodic Table: chemical periodicity

The formula $\text{CH}_3$ may denote an anion, a cation or a free radical. A species with molecular formula $\text{CH}_3$ can behave as an electrophile, a free radical or a nucleophile, depending on how many outer shell electrons the central carbon atom has. How many outer shell electrons are needed for $\text{CH}_3$ to behave in each of these ways?

Chemical bonding

Acrylic acid is made from propene, which is a gaseous product from oil refineries. Which statement about acrylic acid is incorrect?

Carboxylic acids and derivatives

In the reaction route shown below, an alkane is changed into a carboxylic acid over a number of steps. $\text{C}_{10}\text{H}_{22} \xrightarrow{\text{stage 1}} \text{C}_2\text{H}_4 \xrightarrow[\text{catalytic hydration}]{\text{stage 2}} \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{stage 3}} \text{CH}_3\text{CO}_2\text{H}$ What processes take place at stage 1 and at stage 3?

Hydrocarbons

Compound Y is oxidised using warm acidified potassium dichromate(VI). The organic product formed produces an orange precipitate with 2,4-dinitrophenylhydrazine reagent, but it does not produce a silver mirror with Tollens’ reagent. What is Y?

Hydroxy compounds

Compound X causes warm acidified sodium dichromate(VI) to change from orange to green. When 1 mol of X is reacted with 2 mol of HCN in the presence of KCN. What may X be?

Carbonyl compounds

Pentanol, $\text{C}_5\text{H}_{11}\text{OH}$, can form four structural isomers that are primary alcohols. How many of these primary alcohols include a chiral carbon atom?

Chemical bonding

Which isomer of $\text{C}_6\text{H}_{13}\text{OH}$ produces the largest number of different alkenes when it undergoes dehydration?

Hydroxy compounds

The diagram illustrates the structure of the naturally occurring molecule cholesterol. Student X stated that all seventeen carbon atoms in the four rings are situated in one plane. Student Y stated that this molecule shows $cis$-$trans$ isomerism around the $\text{C}=\text{C}$ double bond. Which of the students are correct?

An introduction to AS Level organic chemistry

Which formula shows an ester that will produce sodium ethanoate when it is hydrolysed with aqueous sodium hydroxide?

Carboxylic acids and derivatives

A primary alcohol contains the functional group $-\text{CH}_2\text{OH}$. Which reagent, when used with a primary alcohol under suitable conditions, produces an organic product containing the same number of oxygen atoms as the alcohol?

Hydroxy compounds

During the extraction of aluminium by electrolysis of molten aluminium oxide, why is cryolite mixed with the aluminium oxide?

Electrochemistry

Aldehydes and ketones belong to the family of carbonyl compounds. Which of these react with $\text{NaBH}_4$ and react with Fehling’s reagent?

Chemical bonding

Which of the following are characteristics of metallic copper's structure?

Chemical bonding

The Data Booklet may be used for this question. Zinc reacts with hydrochloric acid according to the equation shown below. $\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2$ Which statements are correct? [All volumes are measured at room conditions.]

Atoms, molecules and stoichiometry

Which of the following statements are correct according to the Brønsted-Lowry theory of acids and bases?

Equilibria

Which statements about the ammonium ion are correct?

Nitrogen and sulfur

The Data Booklet may be needed for this question. The element astatine is placed below iodine in Group VII of the Periodic Table. What properties would astatine show?

Group 17

Which of the following statements are correct?

Atoms, molecules and stoichiometry

Which of the following alkenes could, by reaction with steam at $600\ \text{K}$ and $6 \times 10^6\ \text{Pa}$ in the presence of a phosphoric acid catalyst, give an alcohol with a chiral carbon atom?

Hydrocarbons

Which oxides will react with water to form a solution whose pH is $10$ or above?

The Periodic Table: chemical periodicity

Sorbitol is an artificial sweetener that is used to make chocolate sweet and is suitable for diabetics. Which functional groups may be formed when this molecule undergoes oxidation under appropriate conditions?

Electrochemistry

In waterlogged soils, such as those used for rice growing, the oxygen level is low. In these conditions, anaerobic bacteria remove nitrogen from the soil, as represented by the sequence below. $\text{NO}_3^-(aq) \xrightarrow{A} \text{NO}_2^-(aq) \xrightarrow{B} \text{NO}(g) \xrightarrow{C} \text{N}_2\text{O}(g) \xrightarrow{D} \text{N}_2(g)$ At which step does the change in oxidation number (oxidation state) of nitrogen differ from the changes in the other steps?

Electrochemistry

Bromoethane goes through every conversion shown. Which of these conversions are instances of nucleophilic substitution?

Halogen compounds

During the previous century, the Haber process was occasionally operated at pressures of $1000\ \text{atm}$ and above. Today, it is usually carried out at pressures below $100\ \text{atm}$. What is the reason for this change?

Equilibria

In the diagram, curve X was produced by monitoring the decomposition of $100\ \text{cm}^3$ of $1.0\ \text{mol dm}^{-3}$ hydrogen peroxide, catalysed by manganese(IV) oxide. Which change to the original experimental conditions would produce curve Y?

Reaction kinetics

The diagrams show two Boltzmann distributions. For diagram 1, one of the curves P or Q represents a temperature that is greater than the temperature of the other curve. For diagram 2, one of the lines X or Y represents the activation energy for a catalysed reaction, and the other line represents the activation energy for the same reaction when uncatalysed. Which combination gives the correct curve and line?

Reaction kinetics

$50\ \text{cm}^3$ of $2.50\ \text{mol dm}^{-3}$ hydrochloric acid was poured into a polystyrene beaker with negligible heat capacity. Its temperature was measured, after which $50\ \text{cm}^3$ of $2.50\ \text{mol dm}^{-3}$ NaOH at the same temperature was added rapidly, with stirring. The temperature increased by $17\ ^\circ\text{C}$. For the purposes of the calculation, the final solution can be treated as having a specific heat capacity of $4.2\ \text{J g}^{-1}\ \text{K}^{-1}$. What approximate value would you obtain for the molar enthalpy change of neutralisation of hydrochloric acid and sodium hydroxide from this experiment?

Chemical energetics

The equation shown describes gaseous atoms of non-metal X and hydrogen combining to produce gaseous $\text{X}_2\text{H}_6$ molecules. $2\text{X}(g) + 6\text{H}(g) \rightarrow \text{X}_2\text{H}_6(g) \quad \Delta H = -2775\,\text{kJ mol}^{-1}$ The bond energy for an X-H bond is $395\,\text{kJ mol}^{-1}$. Determine the bond energy of an X-X bond?

Chemical energetics