AS & A Level Chemistry - 9701 Paper 2 2011 Winter Zone 2

Compound A is an organic compound which contains carbon, hydrogen and oxygen.
When 0.240 g of the vapour of A is slowly passed over a large quantity of heated copper(II) oxide, CuO, the organic compound A is completely oxidised to carbon dioxide and water. Copper is the only other product of the reaction.
The products are collected and it is found that 0.352 g of CO₂ and 0.144 g of H₂O are formed.
(a) In this section, give your answers to three decimal places.
(i) Calculate the mass of carbon present in 0.352 g of CO₂.
Use this value to calculate the amount, in moles, of carbon atoms present in 0.240 g of A.
(ii) Calculate the mass of hydrogen present in 0.144 g of H₂O.
Use this value to calculate the amount, in moles, of hydrogen atoms present in 0.240 g of A.
(iii) Use your answers to calculate the mass of oxygen present in 0.240 g of A.
Use this value to calculate the amount, in moles, of oxygen atoms present in 0.240 g of A.

(b) Use your answers to (a) to calculate the empirical formula of A.

(c) When a 0.148 g sample of A was vapourised at 60°C, the vapour occupied a volume of 67.7 cm³ at a pressure of 101 kPa.
(i) Use the general gas equation $pV = nRT$ to calculate $M_r$ of A.
$M_r$ = ...................
(ii) Hence calculate the molecular formula of A.

(d) Compound A is a liquid which does not react with 2,4-dinitrophenylhydrazine reagent or with aqueous bromine.
Suggest two structural formulae for A.

(e) Compound A contains only carbon, hydrogen and oxygen.
Explain how the information on the opposite page about the reaction of A with CuO confirms this statement.

(a) Give the equation, including state symbols, for the first ionisation energy of sulfur.
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(b) Explain why there is a \textit{general} increase in first ionisation energies across the Period from sodium to argon.
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(c) (i) Explain why the first ionisation energy of magnesium is greater than that of aluminium.
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(ii) Explain why the first ionisation energy of phosphorus is greater than that of sulfur.
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(d) (i) Complete the ‘conductivity’ row by using \textit{only} the words ‘high’, ‘moderate’ or ‘low’.
(ii) Complete the ‘melting point’ row by using \textit{only} the words ‘high’ or ‘low’. [Table_1]
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(e) By considering the properties of the third Period elements aluminium to chlorine, suggest the identity of the fourth Period element E.
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(a) State Hess’ Law.

(b) (i) Construct a balanced equation for this reaction.

(ii) Calculate the quantity of heat produced in experiment 1, stating your units.

Use relevant data from the Data Booklet and assume that all solutions have the

same specific heat capacity as water.

(iii) Use your answer to (ii) to calculate the enthalpy change per mole of $\text{K}_2\text{CO}_3$.

Give your answer in kJ mol$^{-1}$ and include a sign in your answer.

(iv) Explain why the hydrochloric acid must be in an excess.

(c) (i) Construct a balanced equation for this reaction.

(ii) Calculate the quantity of heat absorbed in experiment 2.

(iii) Use your answer to (ii) to calculate the enthalpy change per mole of $\text{KHCO}_3$.

Give your answer in kJ mol$^{-1}$ and include a sign in your answer.

(d) When $\text{KHCO}_3$ is heated, it decomposes into $\text{K}_2\text{CO}_3$, $\text{CO}_2$ and $\text{H}_2\text{O}$.

$$2\text{KHCO}_3 \rightarrow \text{K}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O}$$

Use Hess' Law and your answers to (b)(iii) and (c)(iii) to calculate the enthalpy change

for this reaction.

Give your answer in kJ mol$^{-1}$ and include a sign in your answer.

But-1-ene, $\text{CH}_3\text{CH}_2\text{CH}=\text{CH}_2$, is an important compound in the petrochemical industry.

(a) Some reactions of but-1-ene are given below.

In each empty box, draw the structural formula of the organic compound formed.



(b) Compound T reacts with compound U.

Draw the displayed formula of the organic product of this reaction.

Astronomers using modern telescopes of various types have found many molecules in the dust clouds in space. Many of these molecules are those of organic compounds and astronomers constantly look for evidence that amino acids such as aminoethanoic acid, $\text{H}_2\text{NCH}_2\text{CO}_2\text{H}$, are present. One molecule that has been found in the dust clouds is hydroxyethanal, $\text{HOCH}_2\text{CHO}$.

(a) Hydroxyethanal contains two functional groups.

(i) Name, extbf{as fully as you can}, each of the functional groups present in hydroxyethanal.
1 .............................................................
2 .............................................................

(ii) For extbf{each} functional group, identify a reagent that will react with this group and extbf{not} react with the other functional group present. In each case, describe what would be observed when this reaction is carried out.

functional group 1 reagent .......................................
observation .......................................

functional group 2 reagent .......................................
observation ....................................... [7]

(b) Give the extbf{skeletal} formulae of the organic compounds formed when hydroxyethanal is reacted separately with the following.
(i) $\text{NaBH}_4$

(ii) $\text{Cr}_2\text{O}_7^{2-}/\text{H}^+$ under reflux conditions [2]

(c) In a school or college laboratory, it is possible to convert a sample of hydroxyethanal into aminoethanoic acid in a three-step process.

$\text{HOCH}_2\text{CHO} \xrightarrow{\text{step 1}} \text{X} \xrightarrow{\text{step 2}} \text{Y} \xrightarrow{\text{step 3}} \text{H}_2\text{NCH}_2\text{CO}_2\text{H}$
By considering the possible reactions of the functional groups present in hydroxyethanal, you are to deduce a possible route for this conversion.

(c) (i) In the boxes below, draw the structural formulae of your suggested intermediates X and Y.



(ii) State the reagents for extbf{each} of the three steps you have chosen.
step 1 .......................................
step 2 .......................................
step 3 ....................................... [5]