Chemistry 9701/21 — October/November 2016

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

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Topics Atoms, Molecules and Stoichiometry · Introduction to Organic Chemistry · Group IV (Group 14) · Chemical Energetics · Atomic Structure · Group 2 · +4 more

Q1Atoms, Molecules and StoichiometryGroup IV (Group 14)Free sample

A $0.17\text{ g}$ sample of a Group 14 chloride, $\text{XCl}_4$ , reacted with water to produce an oxide, $\text{XO}_2$ , and $\text{HCl}$ .

equation 1 $\quad \text{XCl}_4(\text{s}) + 2\text{H}_2\text{O}(\text{l}) \rightarrow \text{XO}_2(\text{s}) + 4\text{HCl}(\text{aq})$

The $\text{HCl}$ produced was absorbed in $100\text{ cm}^3$ of $0.10\text{ mol}\,\text{dm}^{-3}$ sodium hydroxide solution (an excess).

In a titration, the unreacted sodium hydroxide solution required $30.0\text{ cm}^3$ of $0.20\text{ mol}\,\text{dm}^{-3}$ hydrochloric acid for complete neutralisation.

(a)

Calculate the amount, in moles, of hydrochloric acid used in the titration to neutralise the unreacted sodium hydroxide solution.

\text{amount} = \text{............................ mol}

(b)

Write the equation for the reaction between hydrochloric acid and sodium hydroxide.

(c)

Calculate the amount, in moles, of sodium hydroxide neutralised in the titration.

\text{amount} = \text{............................ mol}

(d)

Calculate the amount, in moles, of sodium hydroxide that reacted with the $\text{HCl}$ produced by the reaction in equation 1.

\text{amount} = \text{............................ mol}

(e)

Calculate the amount, in moles, of $\text{HCl}$ produced by the reaction in equation 1.

\text{amount} = \text{............................ mol}

(f)

Calculate the amount, in moles, of $\text{XCl}_4$ in the original $0.17\text{ g}$ sample.

\text{amount} = \text{............................ mol}

(g)

Calculate the molecular mass, $M_{\text{r}}$ , of $\text{XCl}_4$ .

M_{\text{r}} = \text{............................}

(h)

Calculate the relative atomic mass, $A_{\text{r}}$ , of $\text{X}$ and suggest its identity.

\begin{aligned} A_{\text{r}} \text{ of X} &= \text{............................} \\ \text{identity of X} &\quad \text{.............................................} \end{aligned}

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4 more questions

Q2Chemical Energetics · Atoms, Molecules and Stoichiometry13M
Q3Atomic Structure · Group 2 · Equilibria14M
Q4Introduction to Organic Chemistry · Hydrocarbons · Polymerisation18M
Q5Introduction to Organic Chemistry · Hydroxy Compounds6M

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