[Maximum number: 1]

Sample X is added to water and made up to a total volume of $200 \mathrm{~cm}^{3}$ . This gives a solution of $0.100 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$ .

What is X ?

A

$10 \mathrm{~cm}^{3}$ of $1.00 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$

B

$30 \mathrm{~cm}^{3}$ of $0.90 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$

C

$50 \mathrm{~cm}^{3}$ of $0.40 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$

D

$100 \mathrm{~cm}^{3}$ of $0.30 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{HCl}$

[Maximum number: 1]

Which contains the largest number of hydrogen atoms?

A

0.10 mol of pentane

B

0.20 mol of but-2-ene

C

1.00 mol of hydrogen molecules

D

$6.02 \times 10^{23}$ hydrogen atoms

[Maximum number: 3]

The elements in Group 17 are known as the halogens.

(a)

The concentration of NaClO in bleach S is $x \mathrm{gdm}^{-3}$ .

NaClO reacts with $\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})$ as shown.

\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})+\mathrm{NaClO}(\mathrm{aq}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{NaCl}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{~g})

A $5.00 \mathrm{~cm}^{3}$ sample of S completely reacts with $\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})$ . The volume of $\mathrm{O}_{2}(\mathrm{~g})$ produced is $24.0 \mathrm{~cm}^{3}$ under room conditions.

Assume that only the NaClO in S reacts with $\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})$ .
Calculate x. Show your working.

x=

$\mathrm{g} \mathrm{dm}^{-3}$

[ 3 ]

[Maximum number: 1]

In the Periodic Table, the p block contains elements whose outer electrons are found in the p subshell.

(a)

Sulfur-containing compounds, such as $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{SH}$ , are found in fossil fuels, and produce $\mathrm{SO}_{2}$ when they are burned.

[ 1 ]

(i)

Write the equation to show the complete combustion of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{SH}$ .

[ 1 ]

[Maximum number: 4]

Iron pyrite, $\mathrm{FeS}_{2}$ , has a yellow colour that makes it look like gold metal. The compound contains the ions $\mathrm{Fe}^{2+}$ and $\mathrm{S}_{2}{ }^{2-}$ .

(a)

Iron pyrite is often called fool's gold because of its appearance. Impure samples of iron pyrite often contain a small amount of gold.

The gold can be obtained from impure iron pyrite. The impure iron pyrite is roasted in oxygen, to produce iron(III) oxide and sulfur dioxide. Gold does not react with oxygen.

[ 4 ]

(i)

A sample of impure iron pyrite was roasted in oxygen. The composition of the mixture of solid products is shown.

Calculate the mass of $\mathrm{FeS}_{2}$ present in the sample of impure iron pyrite.
Assume that all the $\mathrm{FeS}_{2}$ was converted to $\mathrm{Fe}_{2} \mathrm{O}_{3}$ during the roasting process.
( $M_{r}: \mathrm{FeS}_{2}$ , 120.0; $\mathrm{Fe}_{2} \mathrm{O}_{3}$ , 159.6)

\text { mass of } \mathrm{FeS}_{2}=

[ 3 ]

(ii)

Use your answer to (iii) to calculate the percentage by mass of gold in this sample of impure iron pyrite. Assume that gold is the only impurity in this sample of impure iron pyrite.

Give your answer to two significant figures.
(If you were unable to calculate an answer to (iii), use 55.00 g as the mass of $\mathrm{FeS}_{2}$ in this calculation. This is not the correct answer.)
percentage by mass of gold = \%

[ 1 ]

[Maximum number: 2]

Combustion data can be used to calculate the empirical formula, molecular formula and relative molecular mass of many organic compounds. Combustion data cannot distinguish between different structural isomers.

(a)

P is a hydrocarbon, $\mathrm{C}_{x} \mathrm{H}_{y^{\prime}}$ . A gaseous sample of P occupied a volume of $25 \mathrm{~cm}^{3}$ at $37^{\circ} \mathrm{C}$ and 100 kPa .

The sample was completely burned in $200 \mathrm{~cm}^{3}$ of oxygen (an excess).
The final volume, measured under the same conditions as the gaseous sample (so that the water produced is liquid and its volume can be ignored), was $150 \mathrm{~cm}^{3}$ .

Treating the remaining gaseous mixture with concentrated alkali, to absorb carbon dioxide, decreased the volume to $50 \mathrm{~cm}^{3}$ .

The equation for the complete combustion of P can be represented as shown.

\mathrm{C}_{x} \mathrm{H}_{y}+\left(x+\frac{y}{4}\right) \mathrm{O}_{2} \rightarrow x \mathrm{CO}_{2}+\frac{y}{2} \mathrm{H}_{2} \mathrm{O}

[ 2 ]

(i)

Use the data given to calculate the value of x.

x=

[ 1 ]

(ii)

Use the data given to calculate the value of $\left(x+\frac{y}{4}\right)$ .

\left(x+\frac{y}{4}\right)=

If you were unable to calculate values in (b)(i) and (b)(ii) then use the data in this box for the remaining parts of this question. These are not the correct values.

x=6 \quad\left(x+\frac{y}{4}\right)=9

[ 1 ]

[Maximum number: 5]

A0.17 g sample of a Group 14 chloride, $\mathrm{XCl}_{4}$ , reacted with water to produce an oxide, $\mathrm{XO}_{2}$ , and HCl.
equation 1

\mathrm{XCl}_{4}(\mathrm{~s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{XO}_{2}(\mathrm{~s})+4 \mathrm{HCl}(\mathrm{aq})

The HC lproduced was absorbed in $100 \mathrm{~cm}^{3}$ of $0.10 \mathrm{~mol} \mathrm{dm}^{-3}$ sodium hydroxide solution (an excess).
In a titration, the unreacted sodium hydroxide solution required $30.0 \mathrm{~cm}^{3}$ of $0.20 \mathrm{~mol} \mathrm{dm}^{-3}$ 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.
amount = mol

[ 1 ]

(b)

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

[ 1 ]

(c)

Calculate the amount, in moles, of sodium hydroxide that reacted with the HCl produced by the reaction in equation 1 .
amount = mol

[ 1 ]

(d)

Calculate the amount, in moles, of HCl produced by the reaction in equation 1.
amount = mol

[ 1 ]

(e)

Calculate the amount, in moles, of $\mathrm{XCl}_{4}$ in the original 0.17 g sample.

amount =mol [1]

[ 1 ]

[Maximum number: 2]

An experiment was carried out to determine the percentage of iron in a sample of iron wire.

(a)

A3.35 g piece of the wire was reacted with dilute sulfuric acid, in the absence of air, so that all of the iron atoms were converted to iron(II) ions. The resulting solution was made up to $250 \mathrm{~cm}^{3}$ .

[ 2 ]

(i)

Calculate the amount, in moles, of dichromate(VI) ions used in the titration.

amount =mol

(ii)

Calculate the amount, in moles, of iron in the 3.35 g piece of wire.

amount =mol [1]

[ 1 ]

(iii)

Calculate the mass of iron in the 3.35 g piece of wire.

mass =g

(iv)

Calculate the percentage of iron in the iron wire.

percentage =% [1]

[ 1 ]

[Maximum number: 3]

Neon is a noble gas.

(a)

A mixture of neon and argon has a mass of 0.275 g . The mixture was placed in a gas syringe at a temperature of $25^{\circ} \mathrm{C}$ and a pressure of 100 kPa . Under these conditions the mixture was found to occupy a volume of $200 \mathrm{~cm}^{3}$ .

[ 3 ]

(i)

Calculate the average $M_{\mathrm{r}}$ of the mixture.
average $M_{\mathrm{r}}=$

[ 2 ]

(ii)

Use your answer to (i) to calculate the percentage of neon in the mixture. Give your answer to three significant figures.
percentage of neon = \%

[ 1 ]

(a)

$10 \mathrm{~cm}^{3}$ of a gaseous hydrocarbon, $\mathrm{C}_{x} \mathrm{H}_{y}$ , was reacted with $100 \mathrm{~cm}^{3}$ of oxygen gas, an excess. The final volume of the gaseous mixture was $95 \mathrm{~cm}^{3}$ .

This gaseous mixture was treated with concentrated, aqueous sodium hydroxide to absorb the carbon dioxide present. This reduced the gas volume to $75 \mathrm{~cm}^{3}$ .

All gas volumes were measured at 298 K and 100 kPa .

[ 6 ]

(i)

Calculate the volume of carbon dioxide produced by the combustion of the hydrocarbon.

\text { volume of } \mathrm{CO}_{2} \text { produced }=\ldots \ldots \ldots \ldots \ldots \ldots . \mathrm{cm}^{3}

[ 1 ]

(ii)

Calculate the volume of oxygen used up in the reaction with the hydrocarbon.

\text { volume of } \mathrm{O}_{2} \text { used }=\ldots \ldots \ldots \ldots \ldots \ldots . . \mathrm{cm}^{3}

[ 1 ]

(iii)

Use your answers to (b)(ii) and (b)(iii), together with the initial volume of hydrocarbon, to balance the equation below.

\ldots \ldots \ldots \ldots . \mathrm{C}_{x} \mathrm{H}_{y}+\ldots \ldots \ldots \ldots . \mathrm{O}_{2} \rightarrow \ldots \ldots \ldots \ldots . \mathrm{CO}_{2}+z \mathrm{H}_{2} \mathrm{O}

[ 1 ]

(iv)

Deduce the values of x, y and z in the equation in (iv).
x=
y=
z=

[ 3 ]