AS & A Level Chemistry - 9701 Paper 1 2011 Winter Zone 1

Three elements, $X, Y$ and $Z$, have the physical properties shown in the table:
[Table_1]
What could be the identities of $X, Y$ and $Z$?

Use of the Data Booklet is relevant to this question.
Lead(IV) chloride will oxidise bromide ions to bromine. The $\text{Pb}^{4+}$ ions are reduced to $\text{Pb}^{2+}$ ions in this reaction.
If 6.980 g of lead(IV) chloride is added to an excess of sodium bromide solution, what mass of bromine would be produced?

Which element has an equal number of electron pairs and of unpaired electrons within orbitals of principal quantum number 2?

Methyl isocyanate, $\text{CH}_3\text{NCO}$, is a toxic liquid which is used in the manufacture of some pesticides.
In the methyl isocyanate molecule, the sequence of atoms is $\text{H}_3\text{C}—\text{N}≡\text{C}=\text{O}$.
What is the approximate angle between the bonds formed by the N atom?

At room temperature and pressure, chlorine does not behave as an ideal gas.
At which temperature and pressure would the behaviour of chlorine become more ideal?
[Table_1]

The standard enthalpy change for the reaction
$$2\text{NF}_3(g) \rightarrow 2\text{N}(g) + 6\text{F}(g)$$ is $\Delta H^\circ = +1668 \text{kJ}$

What is the bond energy of the N–F bond?

When chlorine and aqueous sodium hydroxide are heated together the following overall reaction occurs.
$$3Cl_2(aq) + 6NaOH(aq) \rightarrow 5NaCl(aq) + NaClO_3(aq) + 3H_2O(l)$$
What are the oxidation numbers for chlorine in each of the following species?
[Table_1]

Sulfur dioxide is used as a preservative in wine making.
The following equations describe how sulfur dioxide dissolves.
$$\text{H}_2\text{O} + \text{SO}_2 \rightleftharpoons \text{HSO}_3^- + \text{H}^+$$
$$\text{HSO}_3^- + \text{H}^+ \rightleftharpoons \text{SO}_3^{2-} + 2\text{H}^+$$
Which statement about these two reactions is correct?

An aqueous solution was prepared containing 1.0 mol of $\text{AgNO}_3$ and 1.0 mol of $\text{FeSO}_4$ in 1.00 $\text{dm}^3$ of water. When equilibrium was established, there was 0.44 mol of $\text{Ag}^+(\text{aq})$ in the mixture.
$$\text{Ag}^+(\text{aq}) + \text{Fe}^{2+}(\text{aq}) \rightleftharpoons \text{Ag}(\text{s}) + \text{Fe}^{3+}(\text{aq})$$
What is the numerical value of $K_c$?

When gaseous iodine is heated with hydrogen at 450°C, an equilibrium is established.
$$\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g) \quad \Delta H = +53 \text{kJ mol}^{-1}$$
colourless   purple   colourless
Which change of conditions will cause the purple colour of the equilibrium mixture to become paler?

Which solid-line curve most accurately represents the distribution of molecular speeds in a gas at 500 K if the dotted-line curve represents the corresponding distribution for the same gas at 300 K?

Butanedioate ions can be dehydrogenated to form \textit{trans}-butenedioate ions. The enzyme fumarase speeds up this reaction.
Why does fumarase speed up this reaction?

Which element shows the greatest tendency to form some covalent compounds?

A significant contribution to atmospheric carbon dioxide levels comes from the thermal decomposition of limestone, in the manufacture of cement and of lime for agricultural purposes.
Cement works roast 1000 million tonnes of limestone per year and a further 200 million tonnes is roasted in kilns to make lime.
What is the total annual mass output of carbon dioxide (in million tonnes) from these two processes?

Use of the Data Booklet is relevant to this question.
A 5.00 g sample of an anhydrous Group II metal nitrate loses 3.29 g in mass when heated strongly.
Which metal is present?

Aqueous sodium chloride (brine) is electrolysed by using inert electrodes in a cell which is stirred so that products of electrolysis react with each other. The cell is kept cold.
Which pair of substances is among the major products?

Why do the halogens become less volatile as Group VII is descended?

Total removal of the pollutant sulfur dioxide, $SO_2$, is difficult, both for economic and technical reasons. The quantities emitted from furnace chimneys can be lowered by using desulfurisation plants. The gases are scrubbed (washed) with calcium hydroxide to remove the $SO_2$.
What is the main product formed initially?

Which reaction is endothermic?

This question should be answered by considering the reactions of KMnO₄ with different functional groups under the stated conditions.
The diagram shows the structure of the naturally-occurring molecule cholesterol.

Separate oxidation reactions are carried out using different conditions.
• cold, dilute acidified KMnO₄
• hot, concentrated acidified KMnO₄
Which statements about the products formed are correct?

Many different compounds have been used in aerosol sprays, refrigerators and in making foamed plastics.
Which compound will cause the most ozone depletion?

In the general formula of which class of compound, is the ratio of hydrogen atoms to carbon atoms the highest?

Y and Z are two widely-used selective weed killers.

Which reagent will distinguish Y from Z?

What is involved in the mechanism of the reaction between aqueous sodium hydroxide and 1-bromobutane?

Use of the Data Booklet is relevant to this question.
2.76 g of ethanol were mixed with an excess of aqueous acidified potassium dichromate(VI). The reaction mixture was then boiled under reflux for one hour. The organic product was then collected by distillation.
The yield of product was 75.0%.
What mass of product was collected?

Energy is released in the human body by the oxidation of glucose in a complex sequence of reactions. Part of this sequence is the Krebs cycle. One reaction in the Krebs cycle is the conversion of fumaric acid into malic acid.
\[ \text{HO}_2\text{CCH=CHCO}_2\text{H} \rightarrow \text{HO}_2\text{CCH(OH)CH}_2\text{CO}_2\text{H} \]
fumaric acid malic acid
Which reagents could achieve this transformation in the laboratory?

A reaction between chlorine and propane in ultraviolet light produces two isomeric monochloropropanes, $C_3H_7Cl$, as products. Which information about this reaction is correct? [Table_1]

An unpleasant smelling chemical produced in the human armpit is 3-methylhex-2-enoic acid. If this compound is reacted with a cold, dilute, acidified solution of potassium manganate(VII), how many chiral centres will be produced?

Geraniol is a constituent of some perfumes.
[Image_1: Structural formula of geraniol]
Which statement about geraniol is not correct?

Which pair of substances could react to give the ester CH$_3$CH$_2$CO$_2$CH$_3$?

The definitions of many chemical terms can be illustrated by chemical equations.
Which terms can be illustrated by an equation that shows the formation of a positive ion?
1. first ionisation energy
2. heterolytic fission
3. enthalpy change of atomisation

Why does aluminium chloride, $Al_2Cl_6$, sublime at the relatively low temperature of 180°C?

The three statements that follow are all true.
Which of these can be explained, at least in part, by reference to hydrogen bonding?

1. At 0°C ice floats on water.
2. The boiling point of propan-2-ol is 82°C. The boiling point of propanone is 56°C.
3. At 20°C propanone and propanal mix completely.

A farmer spreads lime on land which has already been treated with an ammonium nitrate fertiliser.
Which reactions will occur in the treated soil?
1. $\text{Ca(OH)}_2 + 2\text{NH}_4^+ (\text{aq}) \rightarrow \text{Ca}^{2+}(\text{aq}) + 2\text{NH}_3 + 2\text{H}_2\text{O}$
2. $\text{Ca(OH)}_2 + 2\text{H}^+(\text{aq}) \rightarrow \text{Ca}^{2+}(\text{aq}) + 2\text{H}_2\text{O}$
3. $\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O}$

Which of the halide ions, chloride, bromide or iodide, acts as a reducing agent when its sodium salt reacts with concentrated sulfuric acid?

In a car engine, non-metallic element X forms a pollutant oxide Y. Further oxidation of Y to Z occurs spontaneously in the atmosphere. In this further oxidation, 1 mol of Y reacts with 0.5 mol of gaseous oxygen.
Which statements about X, Y and Z are correct?
1. X forms a basic hydride.
2. Y is a diatomic molecule.
3. Z is a polar molecule.

Disaccharides, $C_{12}H_{22}O_{11}$, are important in the human diet. For example, sucrose is found in pastries and lactose occurs in milk products. Both of these compounds can be hydrolysed.

$$\text{sucrose + H}_2\text{O} \rightarrow \text{CH}_2\text{OH(CHOH)}_4\text{CHO} + \text{CH}_2\text{OH(CHOH)}_3\text{COCH}_2\text{OH}$$
glucose fructose

$$\text{lactose + H}_2\text{O} \rightarrow \text{CH}_2\text{OH(CHOH)}_4\text{CHO} + \text{CH}_2\text{OH(CHOH)}_4\text{CHO}$$
glucose galactose

Which statements about these hydrolysis products are correct?

1. Glucose and fructose have structural isomers.
2. Glucose and galactose are optical isomers.
3. Glucose and galactose are ketones.

Which observations would be made when testing this substance?

1. Hydrogen is produced when sodium is added.
2. A coloured precipitate is produced when 2,4-dinitrophenylhydrazine reagent is added.
3. A silver precipitate is produced when Tollens’ reagent is added.

[DHA image]
$$\text{HOCH}_2\text{CCH}_2\text{OH}$$
DHA is a colourless liquid which reacts with protein in skin to cause it to darken. It has the structure shown.

On acid hydrolysis, which compounds produce propanoic acid?
1. CH$_3$CH$_2$CO$_2$CH$_3$
2. CH$_3$CH$_2$CH$_2$CN
3. CH$_3$CH$_2$CH$_2$Cl

X is an organic compound. X gives a precipitate with aqueous silver nitrate. Some or all of this precipitate remains undissolved when an excess of dilute aqueous ammonia is added. What could be the identity of X?