Oct/Nov 2023

Sodium azide, $\text{NaN}_3$, is an explosive substance used to fill airbags in cars during crashes. It is made up of positive sodium ions and negative azide ions. What are the numbers of electrons in the sodium ion and the azide ion?

Atomic structure

What does the term standard enthalpy change of neutralisation, $\Delta H^{\ominus}_{\text{neut}}$, mean?

Chemical energetics

HOCl(aq) is the molecule responsible for destroying bacteria when chlorine is introduced into water. This reaction forms that molecule. $\text{Cl}_2(g) + \text{H}_2\text{O}(l) \rightleftharpoons \text{HOCl}(aq) + \text{H}^+(aq) + \text{Cl}^-(aq)$ Which statement about this reaction is correct?

Equilibria

Nitrogen dioxide, $\text{NO}_2$, is in equilibrium with dinitrogen tetroxide, $\text{N}_2\text{O}_4$. $2\text{NO}_2(g) \rightleftharpoons \text{N}_2\text{O}_4(g) \quad \Delta H = -57\,\text{kJ mol}^{-1}$ Under which conditions is the percentage of $\text{N}_2\text{O}_4(g)$ at equilibrium the highest?

Equilibria

If an equimolar blend of $\text{H}_2$ and $\text{I}_2$ is allowed to react, the mole fraction of HI in the equilibrium mixture is $x$. What is the equilibrium constant, $K_p$, for the reaction?

Equilibria

For reaction 1, a student records the initial rate at which $\text{CO}_2(g)$ is formed when $\text{CuCO}_3(s)$ is introduced into $50\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{HNO}_3(aq)$. For reaction 2, the student carries out the same experiment again, but this time with $50\,\text{cm}^3$ of $0.5\,\text{mol dm}^{-3}$ $\text{HNO}_3(aq)$ and the same mass of $\text{CuCO}_3(s)$. In both reaction 1 and reaction 2, the acid is in excess and samples of the same $\text{CuCO}_3$ powder are used. Which row gives the correct answer?

Reaction kinetics

In a reversible reaction, the forward reaction is exothermic and has an activation energy of $+30\,\text{kJ mol}^{-1}$. The reverse reaction follows a mechanism that is precisely the reverse of the forward reaction mechanism. Which statement about the activation energy for the reverse reaction is correct?

Chemical energetics

X, Y and Z are elements that are all located in Groups 13, 14 and 15 of the Periodic Table. X is in the same group in the Periodic Table as Y. Y and Z are both in Period 3. The first ionisation energy of X is higher than that of Y. The melting point of Z is lower than that of Y. Y and Z each form chlorides that are white solids. When these white solids react with water, they give solutions with a pH of less than 4. Which row in the table gives the possible identities of X and Y?

The Periodic Table: chemical periodicity

Which table row concerning silicon, Si, and magnesium, Mg, and their ions is correct?

The Periodic Table: chemical periodicity

Bromocresol green acts as an acid-base indicator. At pH values below 3.8, it appears yellow. At pH values above 5.4, it appears blue. In the range between these values, it is green. Bromocresol green is introduced into the aqueous solution produced when the chloride of element T is added to water. The solution turns yellow. If an excess of the solid oxide of element U is added slowly to this yellow solution, the indicator changes to green and then blue. Which row could be used to identify element T and element U?

The Periodic Table: chemical periodicity

Which row gives the correct descriptions of the separate reactions of calcium and strontium with water?

Group 2

The graph illustrates how first ionisation energy changes as proton number increases for several elements. The letters shown are not the true symbols of the elements. Which statement about the elements is correct?

The Periodic Table: chemical periodicity

L and M are each compounds of Group 2 elements. L and M both dissolve in water. If aqueous solutions of L and M are combined, a white precipitate appears. What could be L and M?

Equilibria

A $5.00\,\text{g}$ sample of an anhydrous Group 2 metal nitrate has a mass loss of $3.29\,\text{g}$ on strong heating. Which metal is present?

Atoms, molecules and stoichiometry

For this question, Q denotes an atom of chlorine, bromine or iodine. Which explanation correctly accounts for the change in volatility as you go down Group 17?

Group 17

Which of the following statements about the halogens or halide ions is correct?

Group 17

When ammonium cyanate is heated without air present, urea, $\text{CO(NH}_2)_2$, is the only substance produced by the reaction. No other products are made. What is the formula of the cyanate ion in ammonium cyanate?

Chemical bonding

Hexamine is a crystalline solid that is used as a fuel for portable stoves. The diagram illustrates its skeletal structure. State the empirical formula of hexamine?

Atoms, molecules and stoichiometry

The compound aspartame is used extensively as a sweetener in ‘diet’ soft drinks. Aspartame is chiral. (There are no chiral carbon atoms in $\text{C}_6\text{H}_5$.) How many chiral carbon atoms are there in one molecule of aspartame?

Chemical bonding

In the molecule $\text{HCCCH}_2\text{CH}_2\text{CHC(CH}_3)_2$, how many $\sigma$ bonds and how many $\pi$ bonds are present?

Chemical bonding

The hydrocarbon $\text{C}_{17}\text{H}_{36}$ may be cracked. Which compound is least likely to form in this reaction?

Hydrocarbons

Which compound has an $M_r$ of $84$ and reacts with HBr to form a product with an $M_r$ of $164.9$?

Atoms, molecules and stoichiometry

Aluminium carbide, $\text{Al}_4\text{C}_3$, reacts readily with aqueous sodium hydroxide. This reaction gives two products: $\text{NaAlO}_2$ and a hydrocarbon. Water molecules also take part as reactants. What is the formula of the hydrocarbon?

Atoms, molecules and stoichiometry

$\beta$-carotene gives carrots their orange colour. Hot, concentrated, acidified $\text{KMnO}_4$ oxidises $\beta$-carotene. During oxidation of one molecule of $\beta$-carotene in this manner, a large number of product molecules are produced. How many of these product molecules have a ketone functional group?

Carbonyl compounds

$1,1$-dichloropropane undergoes reaction with aqueous sodium hydroxide through a sequence of steps to form propanal. $\text{CH}_3\text{CH}_2\text{CHCl}_2 \xrightarrow{\text{NaOH(aq)}} \text{CH}_3\text{CH}_2\text{CHO}$ What term is used to describe the initial step of this reaction?

Halogen compounds

Propanoic acid can be prepared from bromoethane by means of a two-stage synthesis. Which pair of reagents is the most appropriate?

Organic synthesis

Alcohol X forms a yellow precipitate when it is treated with alkaline $\text{I}_2\text{(aq)}$. What is the structure of X?

Hydroxy compounds

If ethanol is allowed to react with sodium metal, ethoxide ions, $\text{CH}_3\text{CH}_2\text{O}^-$, form. If water is allowed to react with sodium metal, $\text{OH}^-$ ions form. Which statement about these reactions and the ethoxide ion is correct?

Hydroxy compounds

Menthol is a naturally occurring alcohol. If menthol is heated with concentrated sulfuric acid, a reaction occurs. One of the products formed is compound T. What is the structure of compound T?

Hydroxy compounds

When it is added to $2,4$-dinitrophenylhydrazine, which compound gives a yellow-orange precipitate?

Carbonyl compounds

Ethanal, $\text{CH}_3\text{CHO}$, reacts with HCN by an addition reaction when $\text{CN}^-$ ions are present. Which row gives the reaction type and the name of the product formed?

Carbonyl compounds

The diagram shows the structure of compound X. What is formed when X is heated with $\text{NaOH(aq)}$?

Carboxylic acids and derivatives

The infrared spectrum for compound L is presented. What is the structure of L?

Analytical techniques

A $35.6\,\text{g}$ sample of hydrated sodium carbonate has sodium ions making up $25.84\%$ of its mass. On heating this sample, anhydrous sodium carbonate and water are produced. Which mass of water is released?

Atoms, molecules and stoichiometry

For compound J, the mass spectrum shows that the peak-height ratio of the M + 1 ion to the M + ion is $4:91$. When compound J is heated with acidified $\text{K}_2\text{Cr}_2\text{O}_7$, it produces a carboxylic acid. What is compound J?

Analytical techniques

At $178\,^{\circ}\text{C}$, solid aluminium chloride sublimes. Which structure most accurately shows the species present in the vapour at this temperature?

Chemical bonding

Which row is the correct one?

Chemical bonding

An evacuated tube with a volume of $400\,\text{cm}^3$ is first empty. After it is filled with gas at $300\,\text{K}$ and $101\,\text{kPa}$, its mass rises by $0.65\,\text{g}$. If the gas is assumed to obey the ideal gas equation, what is the identity of the gas?

States of matter

Nitrogen, $\text{N}_2$, and carbon monoxide, $\text{CO}$, each have $M_r = 28$. The boiling point of $\text{N}_2$ is $77\,\text{K}$, whereas the boiling point of $\text{CO}$ is $82\,\text{K}$. What might account for this difference in boiling points?

States of matter

Which statement concerning enthalpy changes is correct?

Chemical energetics

Which particle is made up of 8 protons, 9 neutrons and 10 electrons?

Atomic structure

Within the solid structure of $\text{SiO}_2$, each silicon atom forms bonds with $x$ oxygen atoms, each oxygen atom forms bonds with $y$ silicon atoms, and every bond is of type $z$. Which combination of $x$, $y$ and $z$ is correct in these statements?

Chemical bonding

Nitric acid is produced industrially by oxidising ammonia. The overall equation for this process is shown below. Equation 1: $\text{NH}_3 + 2\text{O}_2 \rightarrow \text{HNO}_3 + \text{H}_2\text{O}$. This process takes place in three stages. The equations and enthalpy changes for each stage are given. Stage 1: $4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O}$, $\Delta H = -904~\text{kJ mol}^{-1}$. Stage 2: $2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2$, $\Delta H = -114~\text{kJ mol}^{-1}$. Stage 3: $4\text{NO}_2 + \text{O}_2 + 2\text{H}_2\text{O} \rightarrow 4\text{HNO}_3$, $\Delta H = -348~\text{kJ mol}^{-1}$. What is the enthalpy change for the process shown in equation 1?

Chemical energetics

Chlorine reacts with sodium bromide. $\frac{1}{2}\text{Cl}_2 + \text{NaBr} \rightarrow \text{NaCl} + \frac{1}{2}\text{Br}_2$ Which of these words best describes the reaction?

Electrochemistry

The ionic equation for the reaction between aqueous copper ions and aqueous iodide ions is shown below. $2\text{Cu}^{2+}(aq) + 4\text{I}^-(aq) \rightarrow 2\text{CuI}(s) + \text{I}_2(aq)$ What is the change in oxidation state of copper?

Electrochemistry

A gas mixture contains oxygen, nitrogen and argon, and the total pressure is $500\text{ kPa}$. The mixture contains a total of $1.2$ moles of gas. If the oxygen gas by itself filled the whole volume of the mixture, it would produce a pressure of $150\text{ kPa}$. Under room conditions, the quantity of nitrogen gas in the mixture would take up a volume of $5.76\text{ dm}^3$. What is the partial pressure of the argon gas in the mixture?

States of matter

A $1.00\text{ dm}^3$ sealed container is charged with $0.200$ mol of sulfur dioxide and $0.200$ mol of oxygen. The gases are then left to react until equilibrium is attained. $2\text{SO}_2 + \text{O}_2 \rightleftharpoons 2\text{SO}_3$ When equilibrium is established, the container contains $0.100$ mol of $\text{SO}_3$. Calculate the value of $K_c$.

Equilibria

When hydrogen peroxide decomposes in the presence of $\text{MnO}_2$, water and oxygen gas are produced. $2\text{H}_2\text{O}_2(aq) \rightarrow 2\text{H}_2\text{O}(l) + \text{O}_2(g)$ The volume of gas collected after $0.2\text{ g}$ of $\text{MnO}_2$ is added to two different hydrogen peroxide solutions at $20\,^\circ\text{C}$ is displayed on the graph as curves X and Y. Which row identifies the conditions that will give curves X and Y?

Reaction kinetics

The diagram depicts a gas syringe with a piston that can move freely. The syringe holds gaseous hydrogen, gaseous iodine and gaseous hydrogen iodide at equilibrium. $\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g)$ Three alterations are given. 1 raising the total pressure by introducing an inert gas while the volume remains constant 2 raising the pressure by adding more gaseous hydrogen iodide while the volume remains constant 3 lowering the volume by moving the piston to the left Which alterations will produce an equilibrium position where the rate of the forward reaction is increased?

Equilibria

Which row best describes how the melting points and first ionisation energies of the Period 3 elements from sodium to argon vary?

The Periodic Table: chemical periodicity

X and Y are atoms belonging to two different elements in Period 3 of the Periodic Table. Neither X nor Y is argon. X is a non-metal. The atomic radius of X is greater than that of Y. Which statement is correct?

The Periodic Table: chemical periodicity

The second ionisation energy of oxygen is higher than the second ionisation energy of fluorine. Which factor accounts for this difference?

The Periodic Table: chemical periodicity

Four mixtures are each introduced into four separate $50\text{ cm}^3$ water samples and then stirred. Which mixture gives a solution with the greatest pH?

The Periodic Table: chemical periodicity

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

Group 2

The table shows some data for compounds of two elements in Group 2 of the Periodic Table. Calcium compounds: - decomposition temperature of carbonate: $840\ ^\circ\text{C}$ - solubility of sulfate: $4.66 \times 10^{-3}\ \text{mol / 100 g of water}$ - solubility of hydroxide: $1.53 \times 10^{-3}\ \text{mol / 100 g of water}$ Element Z: - decomposition temperature of carbonate: $?$ - solubility of sulfate: $?$ - solubility of hydroxide: $2.00 \times 10^{-5}\ \text{mol / 100 g of water}$ What are the missing values for element Z?

Group 2

Q is a mixture made up of two compounds of Group 2 elements. When Q undergoes thermal decomposition, it forms a white solid and only two gaseous products. One of these gases relights a glowing splint. What might the components of mixture Q be?

Group 2

Iodine has a higher melting point than chlorine. Why is this the case?

States of matter

If concentrated sulfuric acid is added to solid sodium chloride, $\text{HCl}$ is produced, whereas $\text{Cl}_2$ is not. If concentrated sulfuric acid is added to solid sodium iodide, $\text{I}_2$ is produced. Which statement accounts for these results?

Electrochemistry

$\text{NaOH(aq)}$ is mixed with $\text{NH}_4\text{Cl(aq)}$, then the mixture is heated. The gas formed changes damp red litmus paper to blue. Which row is correct?

Nitrogen and sulfur

Artemisinin is a potent anti-malarial medicine. How many chiral centres are present in each molecule of artemisinin?

An introduction to AS Level organic chemistry

Which row gives the correct name and classification for the halogenoalkane displayed? $\text{CH}_3(\text{CH}_2)_2\text{CBr(CH}_3)\text{CH}_2\text{CH}_3$

Chemical bonding

How many geometrical (cis/trans) isomers exist for hex-2,4-diene, $\text{CH}_3\text{CH=CHCH=CHCH}_3$?

Chemical bonding

When zinc is treated with concentrated nitric acid, only three products are formed: zinc nitrate, an oxide of nitrogen and water. $3.0$ moles of zinc react with $8.0$ moles of nitric acid. Zinc nitrate contains $\text{Zn}^{2+}$ ions. What might the formula of the oxide of nitrogen be?

Atoms, molecules and stoichiometry

The diagram shows the structure of compound X. 1 mole of compound X reacts fully with 2 moles of hydrogen bromide. What is the structure of the major product formed in this reaction?

Hydrocarbons

The structural formulae of three compounds are given: $\text{C}_3\text{H}_7\text{CHO}$, $\text{C}_2\text{H}_5\text{COCH}_3$, $\text{CH}_2\text{CHCH}_2\text{CH}_2\text{OH}$. Among these compounds, only one will decolourise bromine water. Among these compounds, only one will give a silver mirror with Tollens’ reagent. Which row gives the correct outcomes?

Carbonyl compounds

Which list includes a compound that is not formed during the free radical substitution of methane with chlorine?

Halogen compounds

Propanoic acid may be converted into propene through a two-stage synthesis. Which row gives reagents that are suitable for this synthesis?

Organic synthesis

Which alcohol gives ethanoate ions when it reacts with alkaline $\text{I}_2(aq)$?

Hydroxy compounds

If compound $X$, $\text{C}_7\text{H}_{14}\text{O}_2$, is heated under reflux with excess acidified potassium dichromate(VI), compound $Y$ is formed. Compound $Y$ gives hydrogen gas with sodium metal and produces orange crystals with 2,4-DNPH reagent. What might $X$ be?

Carbonyl compounds

Which reaction occurs through a nucleophilic addition mechanism?

Carbonyl compounds

Three equations are displayed. $1\quad \text{CH}_3\text{COOH} + \text{MgCO}_3 \rightarrow \text{CH}_3\text{COOMg} + \text{CO}_2 + \text{H}_2\text{O}$ $2\quad \text{CH}_3\text{CH}_2\text{COOH} + \text{Na} \rightarrow \text{CH}_3\text{CH}_2\text{COONa} + \frac{1}{2}\text{H}_2$ $3\quad \text{CH}_3\text{CH}_2\text{COOH} + 2\text{Ba(OH)}_2 \rightarrow \text{CH}_3\text{CH}_2\text{COOBa}_2 + 2\text{H}_2\text{O}$ Which equations are correct?

Atoms, molecules and stoichiometry

What number of esters having the molecular formula $\text{C}_5\text{H}_{10}\text{O}_2$ can be prepared by reacting a primary alcohol with a carboxylic acid?

Carboxylic acids and derivatives

The diagram illustrates an ester. It is heated under reflux with an excess of $\text{NaOH}(aq)$. Which row identifies the 2 products of the reaction?

Carboxylic acids and derivatives

A $3.7$ g portion of copper(II) carbonate is placed into $25~\text{cm}^3$ of $2.0~\text{mol dm}^{-3}$ hydrochloric acid. What volume of gas is generated at room conditions?

Atoms, molecules and stoichiometry

The element oxygen exists as three stable isotopes, $^{16}\text{O}$, $^{17}\text{O}$ and $^{18}\text{O}$. A mass spectrometer was used to examine a sample of oxygen gas, $\text{O}_2$, and each of these isotopes is found in the sample. How many peaks would be expected to be linked with the $\text{O}_2^+$ ion?

Analytical techniques

Ammonium ions, $\text{NH}_4^{+}$, are produced when ammonia gas reacts with hydrogen chloride gas. Which statement about the changes taking place in this reaction is correct?

Chemical bonding

Which characteristic occurs in both ethene and poly(ethene)?

Polymerisation

Two boron compounds are sodium borohydride, $\text{NaBH}_4$, and boron trifluoride, $\text{BF}_3$. What are the molecular shapes of the borohydride ion and the boron trifluoride molecule?

Chemical bonding

For a complete combustion, $0.100$ mol of propan-1-ol is burnt in $12.0~\text{dm}^3$ of oxygen, with both volumes measured at room conditions. What is the volume of the gas mixture at the end, measured at room conditions?

Atoms, molecules and stoichiometry

Under conditions of $2500~\text{K}$ and $1.00\times10^{-4}~\text{Pa}$, a $0.321$ g sample of sulfur vapour occupies $2.08\times10^6~\text{m}^3$. What molecular formula does sulfur have in these conditions?

Atoms, molecules and stoichiometry

Sodium azide, $\text{NaN}_3$, is an explosive substance that is used to fill airbags in cars during crashes. It is made up of positive sodium ions and negative azide ions. What are the numbers of electrons in the sodium ion and the azide ion?

Atomic structure

What is meant by standard enthalpy change of neutralisation, $\Delta H_{\text{neut}}^{\ominus}$?

Chemical energetics

HOCl(aq) is the molecule responsible for killing bacteria when chlorine is introduced into water. This molecule is formed by the reaction below. $\text{Cl}_2(g) + \text{H}_2\text{O}(l) \rightleftharpoons \text{HOCl}(aq) + \text{H}^+(aq) + \text{Cl}^-(aq)$ Which of the statements below about this reaction is correct?

Equilibria

Nitrogen dioxide, $\text{NO}_2$, is in equilibrium with dinitrogen tetroxide, $\text{N}_2\text{O}_4$. $2\text{NO}_2(g) \rightleftharpoons \text{N}_2\text{O}_4(g) \qquad \Delta H = -57\,\text{kJ mol}^{-1}$ Which set of conditions gives the highest percentage of $\text{N}_2\text{O}_4(g)$ at equilibrium?

Equilibria

When equal amounts of $\text{H}_2$ and $\text{I}_2$ are allowed to react, the mole fraction of HI in the equilibrium mixture is $x$. What is the value of the equilibrium constant, $K_p$, for the reaction?

Equilibria

For reaction 1, a student records the initial rate at which $\text{CO}_2(g)$ is formed when $\text{CuCO}_3(s)$ is introduced into $50\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{HNO}_3(aq)$. For reaction 2, the student carries out the same experiment again, but this time with $50\,\text{cm}^3$ of $0.5\,\text{mol dm}^{-3}$ $\text{HNO}_3(aq)$ and the same mass of $\text{CuCO}_3(s)$. In reaction 1 and reaction 2, the acid remains in excess and samples of identical $\text{CuCO}_3$ powder are used. Which row is correct?

Reaction kinetics

The forward step of a reversible reaction is exothermic and has an activation energy of $+30\,\text{kJ mol}^{-1}$. The reverse step follows a mechanism that is the exact opposite of the mechanism for the forward step. Which statement about the activation energy for the reverse reaction is correct?

Reaction kinetics

X, Y and Z are elements that are each located in Groups 13, 14 and 15 of the Periodic Table. X is in the same group in the Periodic Table as Y. Y and Z are both in Period 3. The first ionisation energy of X is higher than the first ionisation energy of Y. The melting point of Z is lower than the melting point of Y. Y and Z each form chlorides that are white solids. When these white solids react with water, they give solutions with a pH of less than 4. Which row in the table gives the possible identities of X and Y?

The Periodic Table: chemical periodicity

Which row gives the correct information about silicon, Si, magnesium, Mg, and their ions?

The Periodic Table: chemical periodicity

Bromocresol green is an acid-base indicator. It is yellow when the pH is below 3.8. It is blue when the pH is above 5.4. It is green between these values. Bromocresol green is then added to the aqueous solution produced when the chloride of element T is mixed with water. The solution changes to yellow. If an excess of the solid oxide of element U is added gradually to this yellow solution, the indicator changes first to green and then to blue. Which row could identify element T and element U?

Equilibria

Which row gives the correct description of the individual reactions of calcium and strontium with water?

Group 2

The graph illustrates how the first ionisation energy changes with proton number for several elements. The letters shown are not the actual symbols of the elements. Which statement about these elements is the correct one?

The Periodic Table: chemical periodicity

L and M are both compounds formed from Group 2 elements. L and M both dissolve in water. If solutions of L and M are mixed together, a white precipitate forms. What could L and M be?

Group 2

When a $5.00\,\text{g}$ portion of an anhydrous Group 2 metal nitrate is heated strongly, its mass decreases by $3.29\,\text{g}$. Which metal is present?

Atoms, molecules and stoichiometry

For this question, Q stands for an atom of chlorine, bromine or iodine. Which explanation is the correct one for the variation in volatility as you move down Group 17?

States of matter

Which statement regarding the halogens or halide ions is correct?

Group 17

When ammonium cyanate is heated in the absence of air, urea, $\text{CO(NH}_2)_2$, is the only substance produced by the reaction. The reaction does not give any other products. What is the formula of the cyanate ion found in ammonium cyanate?

Atoms, molecules and stoichiometry

Hexamine is a crystalline solid that is used as fuel in portable stoves. The diagram below shows its skeletal structure. What is the empirical formula for hexamine?

Atoms, molecules and stoichiometry

The compound aspartame is extensively used as a sweetener in ‘diet’ soft drinks. Aspartame is a chiral compound. (In $\text{C}_6\text{H}_5$, there are no chiral carbon atoms.) How many chiral carbon atoms are present in one molecule of aspartame?

Chemical bonding

How many $\sigma$ bonds and $\pi$ bonds are present in the molecule $\text{HCCCH}_2\text{CH}_2\text{CHC(CH}_3)_2$?

Chemical bonding

The hydrocarbon $\text{C}_{17}\text{H}_{36}$ may be cracked. Which compound is least likely to be formed in this reaction?

Hydrocarbons

A compound with an $M_r$ of $84$ reacts with HBr to form a product with an $M_r$ of $164.9$. Which compound is it?

Atoms, molecules and stoichiometry

Aluminium carbide, $\text{Al}_4\text{C}_3$, undergoes a rapid reaction with aqueous sodium hydroxide. This reaction forms $\text{NaAlO}_2$ and a hydrocarbon as the two products. Water molecules also take part as reactants. What is the formula of the hydrocarbon?

Atoms, molecules and stoichiometry

$\beta$-carotene gives carrots their orange colour. $\beta$-carotene is oxidised by hot, concentrated, acidified $\text{KMnO}_4$. If one molecule of $\beta$-carotene is oxidised in this manner, a large number of product molecules are produced. How many of these product molecules contain a ketone functional group?

Chemical bonding

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

Halogen compounds

Propanoic acid may be prepared from bromoethane by using a two-stage synthesis. Which pair of reagents would be most suitable?

Organic synthesis

X is an alcohol that forms a yellow precipitate with alkaline $\text{I}_2(aq)$. What structure does X have?

Hydroxy compounds

When ethanol reacts with sodium metal, ethoxide ions, $\text{CH}_3\text{CH}_2\text{O}^-$, are formed. When water reacts with sodium metal, $\text{OH}^-$ ions are formed. Which statement correctly describes these reactions and the ethoxide ion?

Equilibria

Menthol is an alcohol that occurs naturally. When menthol is heated with concentrated sulfuric acid, it reacts. One of the substances produced is compound T. What structure does compound T have?

Hydroxy compounds

When 2,4-dinitrophenylhydrazine is added, which compound gives a yellow-orange precipitate?

Carbonyl compounds

Ethanal, $\text{CH}_3\text{CHO}$, reacts with HCN by addition in the presence of $\text{CN}^-$ ions. Which row gives the reaction type and the name of the product produced?

Carbonyl compounds

The structure of compound X is shown. What product is formed when X is heated with $\text{NaOH(aq)}$?

Carboxylic acids and derivatives

Compound L’s infrared spectrum is presented below. What is L’s structure?

Chemical bonding

A $35.6\,\text{g}$ sample of hydrated sodium carbonate has $25.84\%$ sodium ions by mass. If this sample is heated, anhydrous sodium carbonate and water are produced. What mass of water is released?

Atoms, molecules and stoichiometry

In the mass spectrum of compound J, the ratio of the height of the $\text{M}+1$ ion peak to the height of the $\text{M}^+$ ion peak is $4:91$. On heating with acidified $\text{K}_2\text{Cr}_2\text{O}_7$, compound J is changed into a carboxylic acid. Identify compound J.

Analytical techniques

Solid aluminium chloride sublimes at $178\,^{\circ}\text{C}$. Which structure most accurately represents the species present in the vapour at this temperature?

Chemical bonding

Which row is the correct one?

The Periodic Table: chemical periodicity

A tube from which the air has been removed has a volume of $400\,\text{cm}^3$. When it is filled with a gas at $300\,\text{K}$ and $101\,\text{kPa}$, its mass rises by $0.65\,\text{g}$. Take the gas to obey the ideal gas law. State the identity of the gas.

States of matter

Nitrogen, $\text{N}_2$, and carbon monoxide, $\text{CO}$, each have $M_r = 28$. The boiling point of $\text{N}_2$ is $77\,\text{K}$. The boiling point of $\text{CO}$ is $82\,\text{K}$. What might account for this difference in boiling points?

States of matter

Which of the following statements about enthalpy changes is correct?

Chemical energetics