Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

The species $[\text{MnCl}_4]^{2-}$ is a complex ion.
(a(i))[1]

Deduce the oxidation state for manganese in $[\text{MnCl}_4]^{2-}$.

(a(ii))[2]

There are no $180^{\circ}$ bond angles in the $[\text{MnCl}_4]^{2-}$ complex. Draw a three-dimensional diagram to represent the shape of the $[\text{MnCl}_4]^{2-}$ complex. State one bond angle on your diagram.

(b(i))[2]

A solution containing $[\text{Co(H}_2\text{O)}_6]^{2+}$ is treated with excess $\text{NaOH}(aq)$. Write an equation for the reaction. State one observation that can be made straight away after the reaction, including the colour and state of the cobalt-containing product.

(b(ii))[2]

A solution containing $[\text{Co(H}_2\text{O)}_6]^{2+}$ is treated with excess $\text{NH}_3(aq)$. Write an equation for the reaction. State one observation that can be made straight away after the reaction, including the colour and state of the cobalt-containing product.

(b(iii))[2]

A solution containing $[\text{Co(H}_2\text{O)}_6]^{2+}$ is treated with excess $\text{NaCl}(aq)$. Write an equation for the reaction. State one observation that can be made straight away after the reaction, including the colour and state of the cobalt-containing product.

(b(iv))[1]

Name the reaction type that occurs in (b)(iii).

(c(i))[2]

Define what is meant by a bidentate ligand.

(c(ii))[2]

Draw three-dimensional diagrams for the two optical isomers of $[\text{Co(NH}_3)_2(\text{en})_2]^{2+}$. Each en ligand may be shown as $\text{H}_2\text{NCH}_2\text{CH}_2\text{NH}_2$.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: oxidation state is $+2$

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