Chemistry 9701/23 — 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 · Chemical Energetics · Atomic Structure · Group 2 · Hydrocarbons · +1 more

Q1Atoms, Molecules and StoichiometryFree 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 $\text{HCl}$ .

\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 $0.10\text{ mol dm}^{-3}$ sodium hydroxide solution (an excess).

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

(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.

(d)

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

(e)

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

(f)

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

(g)

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

(h)

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

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4 more questions

Q2Chemical Energetics · Atoms, Molecules and Stoichiometry13M
Q3Atomic Structure · Group 214M
Q4Introduction to Organic Chemistry · Hydrocarbons18M
Q5Introduction to Organic Chemistry · Hydroxy Compounds6M

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