AQA GCE AS Level Chemistry AS Paper 1 November 2021 question paper 7404/1

This question is about atomic structure.

Figure 1 is a model proposed by Rutherford to show the structure of an atom.

State two features of the current model that are not shown in the Rutherford model.

Feature 1 of the current model

Feature 2 of the current model

A sample of tin is analysed in a time of flight mass spectrometer. The sample is ionised by electron impact to form 1+ ions.

Table 1 shows data about the four peaks in this spectrum.

Give the symbol, including mass number, of the ion that reaches the detector first.

Calculate the relative atomic mass of tin in this sample. Give your answer to 1 decimal place.

Relative atomic mass

This question is about magnesium and its compounds.

State one observation when magnesium reacts with steam.

Give an equation, including state symbols, for this reaction.

Equation

Describe the bonding in magnesium.

Explain, in terms of structure and bonding, why magnesium chloride has a high melting point.

Give one medical use for magnesium hydroxide.

This question is about redox reactions.

State, in terms of electrons, the meaning of the term oxidising agent.

Cr₂O₇^2– can oxidise SO₃^2– in acidic conditions to form Cr³⁺ and SO₄^2–

Deduce a half-equation for the oxidation of SO₃^2– to SO₄^2–

Deduce a half-equation for the reduction of Cr₂O₇^2– to Cr³⁺

Deduce the overall equation for the oxidation of SO₃^2– by Cr₂O₇^2–

Half-equation for the oxidation of SO₃^2– to SO₄^2–

Half-equation for the reduction of Cr₂O₇^2– to Cr³⁺

Overall equation

This question is about the identification of ions in unknown solutions.

A student completes a number of test-tube reactions on solutions A, B and C.

Table 2 shows the student’s observations.

Suggest the identity of the positive ion in solution A.

Give the simplest ionic equation for the formation of the white precipitate in Test 1 for solution A.

Different gases are formed when solution B reacts in Test 1 and in Test 2.

Suggest the identity of each gas.

Give the simplest ionic equation for the formation of the gas in Test 2.

Gas formed in Test 1

Ionic equation for the formation of the gas in Test 2

The student thinks that solution C contains either chloride ions or bromide ions.

Describe a further test, or tests, to show whether solution C contains chloride or bromide ions.

This question is about chlorine.

Chlorine has a low boiling point because the forces between the molecules are weak.

Explain how these forces arise between molecules of chlorine.

Give an equation for the reaction of chlorine with water.

Give a reason why chlorine is added to drinking water.

Equation

Chlorine reacts with cold, aqueous sodium hydroxide in the manufacture of bleach.

Give an equation for this reaction.

Calcium sulfide reacts with calcium sulfate as shown.

CaS + 3 CaSO₄ → 4 CaO + 4 SO₂

2.50 g of calcium sulfide are heated with 9.85 g of calcium sulfate until there is no further reaction.

Show that calcium sulfate is the limiting reagent in this reaction.

Calculate the mass, in g, of sulfur dioxide formed.

This question is about combustion.

State the meaning of the term standard enthalpy of combustion.

A student does an experiment to determine the enthalpy of combustion of propan-1-ol

Calculate a value, in kJ mol^–1, for the enthalpy of combustion of propan-1-ol in this experiment.

The specific heat capacity of water is 4.18 J K^–1 g^–1

The enthalpy of combustion determined experimentally is less exothermic than that calculated using enthalpies of formation.

Give one possible reason for this, other than heat loss.

A student is provided with a 5.60 g sample of ethanoic acid (CH₃COOH) contaminated with sodium ethanoate (CH₃COONa).

The student dissolves the sample in deionised water and makes the volume up

The student removes 25.0 cm³ samples of the solution and titrates them with 0.350 mol dm^–3 sodium hydroxide solution.

Table 3 shows the results of these titrations.

Use the results in Table 3 to calculate the mean titre value.

Use the mean titre to calculate the percentage by mass of sodium ethanoate in the original sample.

Percentage by mass

The student rinses the burette with deionised water before filling with sodium hydroxide solution.

State and explain the effect, if any, that this rinsing will have on the value of the titre.

Hydrogen can be prepared on an industrial scale using the reversible reaction between methane and steam.

The reaction is done at a temperature of 800 °C and a low pressure of 300 kPa in the presence of a nickel catalyst.

Explain, in terms of equilibrium yield and cost, why these conditions are used.

Sulfur dioxide reacts with oxygen to form sulfur trioxide.

Give an expression for the equilibrium constant (K_c) for this reaction.

A mixture of sulfur dioxide and oxygen is allowed to reach equilibrium in a container of

At equilibrium, the mixture contains 0.176 mol of sulfur dioxide and 0.461 mol of sulfur trioxide.

At temperature T the equilibrium constant, K_c = 15.0 mol^–1 dm³

Calculate the amount, in moles, of oxygen at equilibrium.

Only one answer per question is allowed.

Do not use additional sheets for this working.

In a time of flight mass spectrometer, molecule X is ionised using electrospray ionisation. What is the equation for this ionisation?

What is the electron configuration of V²⁺ in the ground state?

Which molecule is not able to form a co-ordinate bond with another species?

Which species has a square planar shape?

Which bond has the most unsymmetrical electron distribution?

Which compound contains a chlorine atom with an oxidation state of +4?

Which element is classified as a d block element?

Which element in Period 3 has the highest melting point?

Which pair of solutions, when mixed, reacts to form a dark brown solution?

Some solid sodium halides are reacted with concentrated sulfuric acid.

Which solid sodium halide does not produce a sulfur-containing gas as one of the products?

Which atom has one more proton and two more neutrons than³¹₁₅P ?

What is a use for barium sulfate?

Which ion has the largest radius?

Which element has a first ionisation energy lower than that of sulfur?

The first seven successive ionisation energies for element Z are shown.