Chemistry 9701/22 — February/March 2019

Cambridge AS Level · AS Level Structured Questions · worked solutions for every part, with the mark scheme

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Topics Introduction to Organic Chemistry · Atoms, Molecules and Stoichiometry · Chemical Energetics · Hydrocarbons · Carbonyl Compounds · Hydroxy Compounds · +9 more

Q1Nitrogen and SulfurAtoms, Molecules and StoichiometryElectrochemistryChemical EnergeticsHydrocarbonsIntroduction to Organic ChemistryFree sample

Nitrogen, $\text{N}_2$ , is the most abundant gas in the Earth’s atmosphere and is very unreactive.

(a)

State why $\text{N}_2$ is very unreactive.

(b)

Magnesium and lithium both form nitrides with $\text{N}_2$ . These compounds both contain the $\text{N}^{3-}$ ion.

(i)

Write an equation for the reaction of magnesium with $\text{N}_2$ to form magnesium nitride.

(ii)

Solid lithium nitride, $\text{Li}_3\text{N}$ , reacts with water according to the following equation.

\text{Li}_3\text{N(s)} + 3\text{H}_2\text{O(l)} \rightarrow 3\text{LiOH(aq)} + \text{NH}_3\text{(aq)}

State one observation you would make during this reaction.

(c)

(i)

State the industrial importance of ammonia.

(ii)

One method of producing $\text{NH}_3$ is by heating ammonium chloride, $\text{NH}_4\text{Cl}$ , with $\text{CaO}$ .

2\text{NH}_4\text{Cl} + \text{CaO} \rightarrow 2\text{NH}_3 + \text{CaCl}_2 + \text{H}_2\text{O}

Explain why the reaction of $\text{NH}_4\text{Cl}$ with $\text{CaO}$ produces ammonia.

(d)

Three oxides of nitrogen, $\text{NO}$ , $\text{NO}_2$ and $\text{N}_2\text{O}$ , can be formed under different conditions.

(i)

Complete the table to give the oxidation numbers of nitrogen in $\text{NO}$ and $\text{NO}_2$ .

compound	NO	$\text{NO}_2$
oxidation number of N

(ii)

$\text{NO}_2$ can be formed by different chemical reactions.

Write equations for the formation of $\text{NO}_2$ by:

the reaction of $\text{N}_2$ with $\text{O}_2$
the thermal decomposition of magnesium nitrate.

(iii)

Molecules of $\text{N}_2\text{O}$ can be formed by the reaction between $\text{N}_2$ and $\text{O}_2$ . The bond between the N and O atoms ( $\text{N}\rightarrow\text{O}$ ) is a co-ordinate (dative covalent) bond.

2\text{N}_2(\text{g}) + \text{O}_2(\text{g}) \rightarrow 2\text{N}\equiv\text{N}\rightarrow\text{O}(\text{g})

The enthalpy change of reaction for this reaction is $+82 \text{ kJ mol}^{-1}$ .

Calculate the bond enthalpy, in $\text{kJ mol}^{-1}$ , of the $\text{N}\rightarrow\text{O}$ bond.

Use relevant data from the Data Booklet to answer this question.

(e)

Nitrosyl chloride, $\text{NOCl}$ , is a reactive gas that is sometimes formed when $\text{NO}$ reacts with $\text{Cl}_2$ .

nitrosyl_chloride

$\text{NOCl}$ is a strong electrophile and readily undergoes an addition reaction with alkenes.

Complete the diagram to show the mechanism of the electrophilic addition reaction of $\text{NOCl}$ with ethene.

Include all necessary charges, lone pairs and curly arrows, and the structure of the organic intermediate.

mechanism_diagram

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3 more questions

Q2Atoms, Molecules and Stoichiometry · Chemical Bonding · Atomic Structure · Group 17 · Chemical Energetics · States of Matter25M
Q3Carbonyl Compounds · Hydroxy Compounds · Introduction to Organic Chemistry · Analytical Techniques9M
Q4Introduction to Organic Chemistry · Hydrocarbons · Halogen Compounds · Hydroxy Compounds · Carboxylic Acids and Derivatives · Carbonyl Compounds13M

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