AS & A Level Chemistry - 9701 Paper 1 2010 Summer Zone 2

Which gas closely approaches ideal behaviour at room temperature and pressure?

What could be the proton number of an element that has three unpaired electrons in each of its atoms?

Use of the Data Booklet is relevant to this question.
The elements radon (Rn), francium (Fr) and radium (Ra) have consecutive proton numbers in the Periodic Table.
What is the order of their first ionisation energies?
[Table_1]

Some bond energy values are listed below.

[Table_1]

These bond energy values relate to the following four reactions.

P \( \text{Br}_2 \rightarrow 2\text{Br} \)
Q \( 2\text{Cl} \rightarrow \text{Cl}_2 \)
R \( \text{CH}_3 + \text{Cl} \rightarrow \text{CH}_3\text{Cl} \)
S \( \text{CH}_4 \rightarrow \text{CH}_3 + \text{H} \)

What is the order of enthalpy changes of these reactions from most negative to most positive?

Given the following enthalpy changes,

$$I_2(g) + 3Cl_2(g) \rightarrow 2ICl_3(s) \quad \Delta H^\circ = -214 \text{ kJ mol}^{-1}$$
$$I_2(s) \rightarrow I_2(g) \quad \Delta H^\circ = +38 \text{ kJ mol}^{-1}$$

What is the standard enthalpy change of formation of iodine trichloride, $ICl_3(s)$?

Ammonium nitrate, $\text{NH}_4\text{NO}_3$, can decompose explosively when heated.
$$\text{NH}_4\text{NO}_3 \rightarrow \text{N}_2\text{O} + 2\text{H}_2\text{O}$$
What are the changes in the oxidation numbers of the two nitrogen atoms in $\text{NH}_4\text{NO}_3$ when this reaction proceeds?

Which mass of gas would occupy a volume of 3 dm³ at 25°C and 1 atmosphere pressure? [1 mol of gas occupies 24 dm³ at 25°C and 1 atmosphere pressure.]

Use of the Data Booklet is relevant to this question.
2.920 g of a Group II metal, X, reacts with an excess of chlorine to form 5.287 g of a compound with formula XCl₂.
What is metal X?

The table gives the concentrations and pH values of the aqueous solutions of two compounds, X and Y. Either compound could be an acid or a base.
[Table_1]
Concentration (mol dm^-3)
X: 2
Y: 2
pH
X: 6
Y: 9
Student P concluded that X is a strong acid.
Student Q concluded that the extent of dissociation is lower in X(aq) than in Y(aq).
Which of the students are correct?

The Haber process for the manufacture of ammonia is represented by the following equation.
$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \quad \Delta H = -92 \text{ kJ mol}^{-1}$
Which statement is correct about this reaction when the temperature is increased?

The percentage of ammonia obtainable, if equilibrium were established during the Haber process, is plotted against the operating pressure for two temperatures, 400°C and 500°C. Which diagram correctly represents the two graphs?

Swimming pool water can be kept free of harmful bacteria by adding aqueous sodium chlorate(I), NaOCl. This reacts with water to produce HOCl molecules which kill bacteria.
$$ ext{OCl}^- (aq) + ext{H}_2 ext{O} ightleftharpoons ext{OH}^- (aq) + ext{HOCl} (aq)$$
In bright sunshine, the $ ext{OCl}^-$ ion is broken down by ultra-violet light.
$$ ext{OCl}^- (aq) + ext{uv light} ightarrow ext{Cl}^- (aq) + rac{1}{2} ext{O}_2 (g)$$
Which method would maintain the highest concentration of $ ext{HOCl} (aq)$?

Na₂S₂O₃ reacts with dilute HCl to give a pale yellow precipitate. If 1 cm³ of 0.1 mol dm⁻³ HCl is added to 10 cm³ of 0.02 mol dm⁻³ Na₂S₂O₃, the precipitate forms slowly. If the experiment is repeated with 1 cm³ of 0.1 mol dm⁻³ HCl and 10 cm³ of 0.05 mol dm⁻³ Na₂S₂O₃, the precipitate forms more quickly. Why is this?

How does concentrated sulfuric acid behave when it reacts with sodium chloride?

X is a salt of one of the halogens chlorine, bromine, iodine, or astatine (proton number 85).
The reaction scheme shows a series of reactions using a solution of X as the starting reagent.



What could X be?

Which element of the third period requires the least number of moles of oxygen for the complete combustion of 1 mol of the element?

Two properties of non-metallic elements and their atoms are as follows.

property 1: has an oxide that can form a strong acid in water
property 2: has no paired 3p electrons

Which properties do phosphorus and sulfur have?

Consecutive elements X, Y, Z are in the third period of the Periodic Table. Element Y has the highest first ionisation energy and the lowest melting point. What could be the identities of X, Y and Z?

Which property of Group II elements (beryllium to barium) decreases with increasing atomic number?

When gaseous chemicals are transported by road or by rail they are classified as follows.
flamable           non-flammable           poisonous
Which commonly transported gas is non-flammable?

What will react differently with the two isomeric alcohols, $(CH_{3})_{3}CCH_{2}OH$ and $(CH_{3})_{2}CHCH_{2}CH_{2}OH$?

Which reagent will give similar results with both butanone and butanal?

What is formed when propanone is refluxed with a solution of NaBH$_4$?

Which compound is a product of the hydrolysis of $CH_3CO_2C_3H_7$ by boiling aqueous sodium hydroxide?

When heated with chlorine, the hydrocarbon 2,2-dimethylbutane undergoes free radical substitution. In a propagation step the free radical X· is formed.

How many different forms of X· are possible?

When an isomer Y of molecular formula C_4H_9Br undergoes hydrolysis in aqueous alkali to form an alcohol C_4H_9OH, the rate of reaction is found to be unaffected by changes in the concentration of OH^- ions present.
Which is the most likely molecular structure of Y?

Which isomer of $C_4H_{10}O$ forms three alkenes on dehydration?

Which compound exhibits both $\textit{cis-trans}$ and optical isomerism?

In many countries plastic waste is collected separately and sorted. Some of this is incinerated to provide heat for power stations.
Why is pvc, polyvinylchloride, removed from any waste that is to be incinerated?

Polymerisation of 1,1-dichloroethene produces a dense, high melting point substance that does not allow gases to pass through. It is used as cling wrapping.
Which sequence appears in a short length of the polymer chain?

Sodium hydrogensulfide, NaSH, is used to remove hair from animal hides. Which statements about the SH^- ion are correct?
1. It contains 18 electrons.
2. Three lone pairs of electrons surround the sulfur atom.
3. Sulfur has an oxidation state of +2.

Which diagrams represent part of a giant molecular structure?

Which reactions are redox reactions?
1. $\text{CaBr}_2 + 2\text{H}_2\text{SO}_4 \rightarrow \text{CaSO}_4 + \text{Br}_2 + \text{SO}_2 + 2\text{H}_2\text{O}$
2. $\text{CaBr}_2 + 2\text{H}_3\text{PO}_4 \rightarrow \text{Ca(H}_2\text{PO}_4)_2 + 2\text{HBr}$
3. $\text{CaBr}_2 + 2\text{AgNO}_3 \rightarrow \text{Ca(NO}_3)_2 + 2\text{AgBr}$

When organic refuse decomposes in water carboxylic acids are formed. The water becomes acidic and aquatic life is destroyed.
Which additives are suitable to remove this acid pollution?

In a car engine, non-metallic element X forms a pollutant oxide Y. Further oxidation of Y to Z occurs in the atmosphere. In this further oxidation, 1 mol of Y reacts with \( \frac{1}{2} \) mol of gaseous oxygen. What can X be?

Sulfur dioxide and sulfites are used in food preservation.
Why are they used for this purpose?
1. They are reducing agents so retard the oxidation of food.
2. They inhibit the growth of aerobic bacteria.
3. They react with NO₂(g) converting it to NO(g).

Which reactions are examples of nucleophilic substitution?
1. $\text{CH}_3\text{CH}_2\text{Br} + \text{OH}^- \rightarrow \text{CH}_3\text{CH}_2\text{OH} + \text{Br}^-$
2. $\text{CH}_3\text{I} + \text{H}_2\text{O} \xrightarrow{\text{H}^+} \text{CH}_3\text{OH} + \text{HI}$
3. $\text{CH}_3\text{CH}_2\text{CH}_2\text{Cl} + \text{NH}_3 \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2 + \text{HCl}$

Propanoic acid occurs naturally as a result of the bacterial fermentation of milk, and is partly responsible for the flavour of Swiss cheese.

Which starting materials could be used to synthesise propanoic acid?

Which structural formulae represent 2,2-dimethylpentane?
1. $(\text{CH}_3)_2\text{CHCH}_2\text{CH(CH}_3)_2$
2. $(\text{CH}_3)_3\text{CCH}_2\text{CH}_2\text{CH}_3$
3. $\text{CH}_3\text{CH}_2\text{CH}_2\text{C(CH}_3)_3$

The diagram shows some laboratory apparatus.

Which preparations could this apparatus be used for?
1. bromoethane, from ethanol, sodium bromide and concentrated sulfuric acid
2. ethanol, from ethanol, sodium dichromate(VI) and sulfuric acid
3. 1,2-dibromoethane, from bromine and ethene