Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

Atoms and ions of elements consist of the three subatomic particles, protons, electrons and neutrons, present in differing proportions.
(a)[2]

Fill in the table below to show how many of each particle are present in $^{14}\text{C}^{2-}$.

(b)[4]

Describe what you would observe, if anything, when each of the following chlorides reacts with water. Give equations for any reaction that takes place: $\text{CCl}_4$, $\text{GeCl}_4$, $\text{SnCl}_4$.

(c)[1]

Suggest why there is any difference in the reactivities of the chlorides in (b).

(d)[3]

Use the Data Booklet values to explain why aqueous $\text{SnCl}_2$ reacts with $\text{Cl}_2(g)$, whereas aqueous $\text{PbCl}_2$ does not. Write an equation for this reaction.

(e(i))[1]

State how the Faraday constant is related to the Avogadro constant.

(e(ii))[4]

When a current of $1.2\,\text{A}$ was passed through dilute sulfuric acid for $30$ minutes, it was found that $130\,\text{cm}^3$ of oxygen, measured at $25^{\circ}\text{C}$ and $1\,\text{atm}$, was collected at the anode. The following reaction occurs: $2\text{H}_2\text{O}(l) \rightarrow 4\text{H}^+(aq) + \text{O}_2(g) + 4e^-$. Use these data and information from the Data Booklet to calculate a value for the Avogadro constant, $L$, by finding: • the number of moles of oxygen produced, • the number of moles of electrons needed for this, • the number of coulombs passed, • the number of electrons passed, • the number of electrons in one mole of electrons ($L$).

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: In $^{14}\mathrm{C^{2-}}$, the numbers are: protons = 6, electrons = 8, neutrons = 8

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