Chemistry 0620 · IGCSE · Ions and ionic bonds

Ions and ionic bonds — practice question

This question concerns nitrogen compounds.
(a(i))[2]

Write the chemical equation showing how lithium reacts with nitrogen.

(a(ii))[2]

Finish the diagram so that the electronic structure of the nitride ion is shown. Include the charge on the nitride ion.

(b(i))[3]

Using the bond energies provided, calculate the energy change for the reaction of nitrogen with fluorine.

(b(ii))[1]

Using your answer to (i), determine whether this reaction is endothermic or exothermic, and justify it.

(b(iii))[3]

Complete the dot-and-cross diagram to show the electron arrangement in a molecule of $\text{NF}_3$. Use dots to represent electrons from nitrogen and crosses to represent electrons from fluorine. Show only the outer electrons.

(c)[3]

Explain, using attractive forces, why lithium nitride has a much higher melting point than nitrogen trifluoride.

(d(i))[2]

Calculate the mass percentage of nitrogen in ammonium nitrate.

(d(ii))[1]

State one agricultural use of ammonium nitrate.

(d(iii))[1]

State the name of a compound that can displace ammonia from ammonium nitrate.

(e(i))[1]

Define what is meant by the term base.

(e(ii))[1]

Suggest a pH value for aqueous ammonia.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Balanced equation: $6\text{Li} + \text{N}_2 \rightarrow 2\text{Li}_3\text{N}$.

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