Feb/March 2023

Four equations showing reactions of nitrogen or a compound of nitrogen are given. Which equation shows a disproportionation reaction?

Electrochemistry

The chemical equation for a reaction is given below. Every substance is in its standard state. $\text{XeF}_6 + 3\text{H}_2\text{O} \rightarrow \text{XeO}_3 + 6\text{HF}$ Which statement gives the standard enthalpy change of reaction for this reaction?

Chemical energetics

Molten aluminium chloride has a simple molecular structure. Every molecule contains two aluminium atoms and six chlorine atoms. Which statement is correct?

Chemical bonding

Which atom has four times as many neutrons as the $^{7}_{3}\text{Li}$ atom?

Atomic structure

Which statement correctly describes the first ionisation energies of magnesium and neon?

The Periodic Table: chemical periodicity

In a sample of pure water, what is the greatest number of hydrogen bonds that a single water molecule can take part in?

Chemical bonding

When hydrated cobalt(II) sulfate is heated, it loses water and forms anhydrous cobalt(II) sulfate. All of the water of crystallisation is released into the atmosphere as steam. If $3.10\,\text{g}$ of hydrated cobalt(II) sulfate, $\text{CoSO}_4\cdot x\text{H}_2\text{O}$, is heated until a constant mass is reached, the mass falls by $1.39\,\text{g}$. What is the value of $x$, to the nearest whole number?

Atoms, molecules and stoichiometry

The table lists bond energies for a selection of diatomic molecules. Deuterium, D, is an isotope of hydrogen. Which statements are correct?

Chemical bonding

Two procedures are given. 1. Sulfur is burnt in excess oxygen, and then NO is added to the mixture of products. 2. Sulfur is burnt in excess oxygen, and then $\text{NO}_2$ is added to the mixture of products. Which of these procedures will result in some sulfur trioxide, $\text{SO}_3$?

Nitrogen and sulfur

Powder P is a mixture of two substances chosen from $\text{AgCl}$, $\text{AgBr}$ and $\text{AgI}$. P is shaken with dilute aqueous ammonia. A yellow solid, Q, is left behind. The mixture is then filtered, and Q is rinsed and dried. The filtrate is gathered and added to aqueous nitric acid to form a white precipitate, R, which is filtered off, washed and dried. Q and R are each warmed separately with concentrated sulfuric acid, $\text{H}_2\text{SO}_4$. Which observations are made?

Group 17

Two Period 3 elements, X and Y, each react separately with oxygen to produce solid oxides. The oxide of X does not dissolve in water. The oxide of Y dissolves in water, giving a solution that can dissolve the oxide of X. What could X and Y be?

The Periodic Table: chemical periodicity

The diagram illustrates the Boltzmann distribution for one mole of a gas. This gas reacts in a reaction with activation energy, $E_a$. Which statement correctly explains the effect of an increase in temperature?

Reaction kinetics

Which row gives the structure and bonding of $\text{SiO}_2$ and $\text{SiCl}_4$?

Chemical bonding

A sample that contains $0.010\,\text{mol}$ of anhydrous calcium nitrate is heated strongly until decomposition is complete. The entire gas formed is collected, and its volume is measured under room conditions. What is the volume of gas produced?

Atoms, molecules and stoichiometry

V and Z are both Period 3 elements in the Periodic Table. Each one forms a single stable ion that contains no other element. The atomic radius of each element and the ionic radius of the ion mentioned above are shown. Which statement is true?

The Periodic Table: chemical periodicity

As you move down Group 2 of the Periodic Table, the properties of the elements and their compounds change in a regular pattern. Which property decreases from magnesium to barium?

Group 2

A list shows four properties of beryllium, Be, or a beryllium compound. Which one of these properties is unlike the property of magnesium or the corresponding magnesium compound?

Group 2

Which two formulae correctly show a pair of structural isomers?

Carboxylic acids and derivatives

Which reagents and conditions would lead to the production of butanenitrile, $\text{CH}_3\text{CH}_2\text{CH}_2\text{CN}$?

Organic synthesis

Compound X, $\text{C}_7\text{H}_{13}\text{Br}$, undergoes reaction with hot alcoholic NaOH to form two products, Y and Z. When Y is reacted with $\text{Br}_2$, it forms a product, $\text{C}_7\text{H}_{12}\text{Br}_2$, that is present as a mixture of four optical isomers. When Z is reacted with $\text{Br}_2$, it forms a product, $\text{C}_7\text{H}_{12}\text{Br}_2$, that is non-chiral. What might X be?

Halogen compounds

If illudin S is warmed under reflux with excess acidified potassium dichromate(VI), compound M is produced. What molecular formula does compound M have?

Electrochemistry

Cyclohexene, $\text{C}_6\text{H}_{10}$, is a hydrocarbon containing a ring of six carbon atoms. It also has a number of structural isomers that are straight-chain alkenes. In each of these molecules, the number of double bonds is P. What is the shape of the cyclohexene molecule and what is the value of P?

Chemical bonding

A student performs four tests to study the rate of reaction between $3.0\,\text{g}$ of calcium carbonate and hydrochloric acid. $\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{CO}_2(g) + \text{H}_2\text{O}(l)$ test 1: $\text{CaCO}_3$ powder + $2.0\,\text{mol dm}^{-3}\,\text{HCl}$ at $35\,^\circ\text{C}$ test 2: $\text{CaCO}_3$ powder + $2.0\,\text{mol dm}^{-3}\,\text{HCl}$ at $35\,^\circ\text{C}$ test 3: large chips of $\text{CaCO}_3$ + $1.0\,\text{mol dm}^{-3}\,\text{HCl}$ at room temperature test 4: large chips of $\text{CaCO}_3$ + $1.0\,\text{mol dm}^{-3}\,\text{HCl}$ at $35\,^\circ\text{C}$ The student gathers the $\text{CO}_2(g)$ and measures the time needed to obtain the same gas volume in each test. Which set of times could be correct for the four tests?

Reaction kinetics

Exhaust gases from an internal combustion engine are made less harmful when they are passed through a catalytic converter. Several reactions occur in the catalytic converter. Two of these reactions are shown in the table. Which row is the correct one?

Reaction kinetics

Which compound undergoes reaction most rapidly with aqueous silver nitrate via an $\text{S}_\text{N}1$ mechanism?

Halogen compounds

Tartaric acid, $\text{HOOCCH(OH)CH(OH)COOH}$, occurs in many plants. When a sample of tartaric acid is treated with an excess of $\text{LiAlH}_4$, the organic product J is formed. What changes are observed when $\text{NaOH(aq)}$ is added to separate samples of tartaric acid and J?

Equilibria

Citric acid can be changed into tricarballylic acid in two steps. A compound intermediate, Q, is produced. Which reagents are required for each step?

Organic synthesis

When answering this question, you should take both structural isomerism and stereoisomerism into account. P has the molecular formula $\text{C}_5\text{H}_{10}\text{O}$. P gives an orange precipitate with 2,4-dinitrophenylhydrazine (2,4-DNPH reagent). How many isomeric structures are possible for P?

An introduction to AS Level organic chemistry

The two isomeric alcohols W and X each have the molecular formula $\text{C}_4\text{H}_9\text{OH}$. When W is oxidised, it forms carbonyl compound Y, and Y produces a red precipitate with Fehling's solution. When X is oxidised, it forms carbonyl compound Z, and Z does not produce a red precipitate with Fehling's solution. Which of W and X forms a yellow precipitate with alkaline $\text{I}_2$(aq)?

Hydroxy compounds

The ester ethyl butanoate may be hydrolysed with an excess of dilute sodium hydroxide solution. Which substance is formed in this reaction?

Atoms, molecules and stoichiometry

In an aqueous solution, there are $4.00\,\text{g}$ of the carboxylic acid, Q. If this solution is reacted with excess magnesium, $380\,\text{cm}^3$ of gas is given off, measured at s.t.p. Determine the relative formula mass of Q.

Atoms, molecules and stoichiometry

An infrared spectrum for an organic compound is displayed. Which compound might produce this spectrum?

Chemical bonding

Cyclohexa-1,4-diene is reacted with bromine dissolved in tetrachloromethane, with no light present. Which product is produced?

Hydrocarbons

The table gives the partial pressures in an equilibrium mixture produced by the Haber process. $3\text{H}_2(g) + \text{N}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ What is the value, by number, of the equilibrium constant, $K_p$, for this reaction?

Equilibria

2-methylbut-2-ene is treated with hot, concentrated, acidified potassium manganate(VII) solution. Which products are formed in this reaction?

Hydrocarbons

The following reversible reaction is given. $2\text{NOCl}(g) \rightleftharpoons 2\text{NO}(g) + \text{Cl}_2(g) \qquad \Delta H = +77.0\,\text{kJ mol}^{-1}$ Which alteration in conditions would shift the equilibrium position to the right and increase the value of the equilibrium constant?

Equilibria

The ore psilomelane can be represented by the overall formula $\text{Ba}((\text{Mn}^{x+})(\text{Mn}^{y+}))_8\text{O}_{16}(\text{OH})_4$. In this overall formula, $x+$ and $y+$ are the two distinct oxidation states of manganese present in psilomelane. What might the values of $x$ and $y$ be?

Atoms, molecules and stoichiometry

Silicon reacts with a blend of calcium oxide and magnesium oxide at $1200\,^\circ\text{C}$. $2\text{MgO} + 2\text{CaO} + \text{Si} \rightarrow 2\text{Mg} + \text{Ca}_2\text{SiO}_4$ Which statement concerning this reaction is correct?

Electrochemistry

Which species contains a lone pair of electrons?

Chemical bonding

In which conditions will nitrogen act most nearly as an ideal gas?

States of matter

The Pauling electronegativity values of elements may be used to forecast the chemical behaviour of compounds. Use the data in Table 1.1 to answer the questions that follow.

The Periodic Table: chemical periodicity

The Group 2 elements Mg to Ba are all reactive, silvery-white metals.

Group 2

Alkenes react by addition with a $1{:}1$ blend of $ ext{CO}$ and $ ext{H}_2$ to give aldehydes. Fig. 3.1 illustrates the reaction of propene with a $1{:}1$ blend of $ ext{CO}$ and $ ext{H}_2$.

Carbonyl compounds

Fig. 4.1 illustrates several reactions of compound D, 2-bromobutane.

Polymerisation

The zinc mineral most commonly found contains zinc(II) sulfide, ZnS.

Chemical energetics

Hypophosphorous acid is an inorganic acid. Its conjugate base is $\text{H}_2\text{PO}_2^{-}$.

Electrochemistry

Vanadium belongs to the transition elements in Period 4 of the Periodic Table.

Chemistry of transition elements

Ethylamine and phenylamine belong to the class of primary amines.

Nitrogen compounds

Tulobuterol is present in some medicines.

Hydrocarbons

A student applies thin-layer chromatography (TLC) to examine a mixture that contains several different metal cations. The student carries out the test again with different solvents. Fig. 6.1 presents the chromatogram the student produced using water as the solvent.

Analytical techniques