AS & A Level Chemistry - 9701 Paper 2 2019 Summer Zone 3

(a) A sample contains three different types of atom: $^{40}_{18}\text{Ar}$, $^{40}_{19}\text{K}$ and $^{40}_{20}\text{Ca}$.

(i) State fully, in terms of the numbers of subatomic particles, what these three atoms have in common.
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(ii) State fully, in terms of the numbers of all subatomic particles, how these three atoms differ from each other.
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(b) A sample of sulfur contains only two isotopes, $^{32}\text{S}$ and $^{34}\text{S}$. The relative atomic mass of this sample is 32.09.

$$\begin{array}{|c|c|}\hline \text{isotope} & \text{isotopic mass} \\ \hline ^{32}\text{S} & 32.0 \\ \hline ^{34}\text{S} & 34.0 \\ \hline \end{array}$$

Calculate the percentage abundance of the isotopes present in this sample.

% abundance $^{32}\text{S}$ = .........................................................

% abundance $^{34}\text{S}$ = ......................................................... [3]

(c) The electronic configuration of a sulfur atom is $1s^22s^22p^63s^23p^4$.

(i) Identify which orbital in a sulfur atom has the lowest energy.
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(ii) Sketch the shape of a p orbital.

[1]

(iii) During the process of ionisation a sulfur atom loses an electron.

$$\text{S}(g) \rightarrow \text{S}^+(g) + e^- \quad \Delta H = 1000\text{kJ mol}^{-1}$$

Identify the orbital from which this electron is removed. Explain your answer.
orbital ......................................................................................................................
explanation ........................................................................................................
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(d) (i) Complete the diagram to show the arrangement of electrons within the third shell of a phosphorus atom.

[Image placeholders of the boxes for orbitals]

3s     3p
[1]

(ii) Explain why the first ionisation energy of sulfur is less than that of phosphorus.
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(a) (i) At room temperature, iodine solid has a lattice structure.
Describe the arrangement of the iodine molecules within the solid.
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(a) (ii) List all of the forces of attraction present in solid iodine and identify which of these are
overcome when solid iodine is heated to produce iodine vapour.
force(s) of attraction present
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force(s) of attraction overcome
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(b) (i) How many co-ordinate (dative covalent) bonds are made when a molecule of $Al_2I_6$ is
formed from its atoms?
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(b) (ii) Describe how co-ordinate (dative covalent) bonds form within this molecule.
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(c) (i) Write an equation for this reaction.
You may wish to use oxidation numbers to help you.
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(c) (ii) Explain, with reference to oxidation numbers, why this reaction is a redox reaction.
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(a) Magnesium reacts with oxygen to form magnesium oxide.

State two observations that would be made when magnesium is heated strongly and placed in a gas jar of pure oxygen.

(b) Acid indigestion is caused by an excess of hydrochloric acid in the stomach. Magnesium oxide is commonly found in indigestion tablets.

(i) Give the equation to show how magnesium oxide relieves acid indigestion.  

(ii) Name the type of reaction that occurs in (b)(i).  

(c) Magnesium oxide is described as a ceramic material. It has a high melting point.

State and explain why ceramic materials such as magnesium oxide have high melting points.  

(d) Magnesium oxide can be made from magnesium carbonate in a one-step reaction using heat.

(i) Write an equation for this reaction. Include state symbols.  

(ii) Name the type of reaction occurring during this process.  

Release of sulfur dioxide, $SO_2$, into the atmosphere causes acid rain.
(a) Explain why high levels of $SO_2$ may be found in the atmosphere near power stations that burn fossil fuels.
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(b) The $SO_2$ released can be converted in the atmosphere into sulfuric acid, $H_2SO_4$, by reaction with nitrogen dioxide gas, $NO_2$, and water, $H_2O$.
$$SO_2 + NO_2 \rightarrow NO + SO_3$$
$$SO_3 + H_2O \rightarrow H_2SO_4$$
During one year, 1590 tonnes of $SO_2$ was released into the atmosphere by a fossil-fuel burning power station.
(i) Use the equations to calculate how many tonnes of $H_2SO_4$ were formed in the atmosphere. Assume that all of the $SO_2$ released was converted into $H_2SO_4$.
mass of $H_2SO_4$ = ............................... tonnes [2]
(ii) Describe how $NO_2$ is also produced by these power stations.
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(iii) State one natural cause of $NO_2$ being formed in the atmosphere.
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(iv) Explain why $NO_2$ can be described as a catalyst in the oxidation of atmospheric $SO_2$.
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Halogenoalkanes react with a number of different reagents in nucleophilic substitution reactions.
(a) A sample of potassium cyanide dissolved in ethanol is added to a sample of 1-bromobutane, CH₃(CH₂)₃Br, and heated under reflux. A nucleophilic substitution reaction occurs and compound A is formed.
(i) Name compound A.
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(ii) What is meant by the term nucleophile?
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(iii) Identify the nucleophile in this reaction.
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(iv) Explain why this reaction is described as a substitution reaction.
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(b) State the reagent(s) and conditions needed for CH₃(CH₂)₂Br to react to form CH₃(CH₂)₃NH₂.
reagent(s) ..................................................................................................
conditions................................................................................................. [2]
(c) Equal amounts of three different halogenoalkanes are added to three separate test-tubes. An equal amount of aqueous silver nitrate and ethanol is added to each test-tube. The time taken for a precipitate to form is recorded for each halogenoalkane.

(i) Describe and explain the trend in reactivity of the different halogenoalkanes shown in this experiment.
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(ii) All three halogenoalkanes tend to react via the $S_N1$ mechanism.
Explain why the $S_N1$ mechanism is favoured.
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(iii) Identify a halogenoalkane which tends to react with an aqueous solution of silver nitrate and ethanol via the $S_N2$ mechanism.
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(a) Three alkenes, X, Y and Z, have the same molecular formula.
(i) Describe what is seen when aqueous bromine is added to X.
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[1] X, Y and Z are reacted separately with hot, concentrated, acidified manganate(VII) ions until no further reaction occurs. The carbon-containing products are shown in the table.