Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

(a)[2]

Write a balanced equation for the reaction of each of these chlorides with water. phosphorus(V) chloride. silicon(IV) chloride.

(b)[2]

When sulfur is heated under pressure with chlorine, the main product is $\text{SCl}_2$ (Cl-S-Cl). $\text{S}_8(g) + 8\text{Cl}_2(g) \rightarrow 8\text{SCl}_2(g)$ Use the Data Booklet to calculate the enthalpy change, $\Delta H$, for this reaction. The eight sulfur atoms in the $\text{S}_8$ molecule are all joined in a single ring by single bonds.

(c(i))[1]

State the oxidation number of sulfur in $\text{SCl}_2$.

(c(ii))[1]

Determine how the oxidation number of sulfur changes during the reaction of $\text{SCl}_2$ with water.

(c(iii))[1]

Suggest which compound B is.

(c(iv))[2]

Construct an equation for the reaction of $\text{SCl}_2$ with water.

(c(v))[7]

State the observations when each of the following reagents is added to separate samples of solution A? $\text{AgNO}_3(aq)$ $\text{K}_2\text{Cr}_2\text{O}_7(aq)$

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: $\mathrm{PCl_5 + 4H_2O \rightarrow H_3PO_4 + 5HCl}$

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