DEPARTMENT FOR CURRICULUM, LIFELONG LEARNING AND EMPLOYABILITY Directorate for Learning and Assessment Programmes Track 2 Educational Assessment Unit

Annual Examinations for Secondary Schools 2021

YEAR 11 CHEMISTRY TIME: 2 hours

Name: ______Class: ______

Useful Atomic numbers and relative atomic masses are shown in the periodic table printed below. Data One mole of any gas occupies 22.4 dm3 at standard temperature (0 °C / 273 K) and pressure (1 atm. / 760 mmHg / 101.3 kPa). Faraday constant = 96500 C mol-1 Q = I t

PERIODIC TABLE

Marks Grid [For Examiner’s use only]

Question Section A Section B No. 1 2 3 4 5 6 7 8 9 10 11 12 Max. Theory 6 6 6 6 6 6 6 6 12 20 20 20 Mark Total Actual Mark

Chemistry – Year 11 – Track 2 – 2021 Page 1 of 12 Section A: Answer ALL questions in the spaces provided. This section carries 60 marks.

1) Chlorine is an element. It has two isotopes, chlorine-35 and chlorine-37. a) What do the following words mean? i) Element

______(1)

ii) Isotopes

______(1)

b) Draw a labelled diagram of the atomic structure of the chlorine-37 isotope. Indicate the number of protons and neutrons in the nucleus.

(2)

c) Given that the percentage abundance of chlorine-35 is 75% while that of chlorine-37 is 25%, show how the relative atomic mass of chlorine is 35.5.

______

______

______(1)

d) Chlorine exists as a gas in nature. Write the chemical formula of chlorine gas.

______(1)

2) By referring to the Periodic Table provided: a) Name the group of elements found between groups 2 and 3.

______(1)

b) How does the atomic size of the elements change when going down a group of elements? Explain your answer in terms of electron configuration.

______

______(2)

Page 2 of 12 Chemistry – Year 11 – Track 2 – 2021 c) How does the valency of elements change when going from left to right in period 3 of the Periodic Table? ______

______(2)

d) Silicon and germanium are metalloid elements. Explain what the word metalloid means. ______(1)

3) Seawater contains many dissolved salts as well as dissolved covalent compounds. a) Sodium chloride is by far the most abundant salt found in seawater. Draw a dot-cross diagram of sodium chloride showing all electron shells.

(3)

b) Water is the main component of seawater. Draw a dot-cross diagram of water showing outer shell electrons only.

(3)

4) Nitrogen dioxide can be produced in a laboratory by heating lead(II) nitrate. a) Write a balanced chemical equation for the above decomposition reaction. ______(2)

b) State a safety precaution related to this particular experiment. ______(1)

c) Write a balanced chemical equation to represent what happens when nitrogen dioxide reacts with water. ______(2)

d) Mention one negative effect caused by the presence of nitrogen dioxide in air. ______(1)

Chemistry – Year 11 – Track 2 – 2021 Page 3 of 12 5) This question is about acids, bases and salts. a) Distinguish between a base and an alkali. ______

______(1)

b) Give one example of an insoluble base and one example of an alkali. ______(2)

c) State one property of acids. ______(1)

d) In a reaction between sulfuric acid and potassium hydroxide, an acid salt may be produced. Write a balanced chemical equation to represent this reaction. ______(2)

6) Iron is a transition metal. a) Mention one property that is common to transition metals. ______(1)

b) Identify the iron compound produced when iron reacts with: i) hydrochloric acid. ______(1)

ii) chlorine. ______(1)

c) State what happens to the compound mentioned in part b) i) when it is allowed to stand in air. ______(1)

d) Describe a test including the expected results that is used to distinguish between the two forms of iron compounds mentioned in part b). ______

______

______(2)

7) A concentrated solution of potassium chloride is electrolysed using inert electrodes. a) Draw a simple labelled diagram of the laboratory apparatus used in this experiment.

(2)

Page 4 of 12 Chemistry – Year 11 – Track 2 – 2021 b) State the ion that is selectively discharged at: i) the cathode. ______(1)

ii) the anode. ______(1)

c) Write the ionic half equation that occurs at the anode. ______(2)

8) Tests were performed on two substances, A and B. a) When a flame test was performed on a solid sample of substance A, a blue- green flame was produced. On adding sodium hydroxide solution to a solution of substance A, a blue precipitate insoluble in excess formed. On adding drops of acidified silver nitrate solution to a solution of substance A, a white precipitate formed that turned violet when exposed to direct sunlight. Substance A is: ______(2)

b) Substance B is a white solid which is insoluble in water. Substance B decomposes on strong heating to produce a white solid C and a gas that turns limewater milky. Substance C reacts with water to produce an alkaline solution. A flame test on a sample of the alkaline solution produced a brick red flame. Substance B is: ______(2)

c) Write an ionic equation, omitting spectator ions, for the reaction between a solution of substance A and sodium hydroxide solution. ______(2)

9) Natural gas and crude oil are mixtures of hydrocarbons that are found in natural underground deposits. a) What is the difference between natural gas and crude oil? ______

______(1)

b) Name the process that is used in industry to separate the various components of crude oil. ______(1)

c) Describe briefly how the various hydrocarbons in crude oil are separated from each other in the process mentioned in part b). ______

______

______

______

______

______(3)

Chemistry – Year 11 – Track 2 – 2021 Page 5 of 12 d) Draw the structural formula for the following hydrocarbons: i) pentane

(1)

ii) ethene

(1)

iii) propyne

(1)

e) Write the general formula for alkynes.

______(1)

f) Which of the hydrocarbons mentioned in part d) undergo substitution reactions only?

______(1)

g) The reaction of bromine with hydrocarbons is used to distinguish between saturated and unsaturated hydrocarbons. i) Write the structural formula of the product between bromine and ethene.

______(1)

ii) Describe what is observed during this reaction which confirms that ethene is unsaturated.

______(1)

Page 6 of 12 Chemistry – Year 11 – Track 2 – 2021 Section B: Answer any TWO questions only in the spaces provided. This section carries 40 marks.

10) You are asked to carry out an experiment to determine the order of reactivity of the following metals: copper, iron and magnesium. You are provided with the following list of materials: copper turnings, iron filings, magnesium turnings, copper(II) nitrate, iron(III) nitrate and magnesium nitrate. a) Describe an experiment that shows the order of reactivity of these metals. Your answer should include:

i) A method.

______

______

______

______

______(2)

ii) Fill in the following table to indicate whether a reaction takes place or not.

Solution of Solution of Solution of

copper(II) ions iron(III) ions magnesium ions Copper No reaction Iron

Magnesium (4)

iii) Any TWO ionic equations including state symbols.

______

______

______

______(6)

iv) A conclusion regarding the order of reactivity of the metals.

______

______

______(2)

Chemistry – Year 11 – Track 2 – 2021 Page 7 of 12 b) Consider the following equation for the reaction between iron and chlorine gas:

2Fe(s) + 3Cl2(g) → 2FeCl3(s)

For the reaction above: i) Which substance was oxidised and which was reduced?

Substance oxidised: ______(1)

Substance reduced: ______(1)

ii) State the change in oxidation number of chlorine during the reaction.

______(2)

iii) Write a balanced ionic half equation for iron.

______(2)

11) An experiment was performed to investigate the rate of a chemical reaction. The reagents used were a few calcium carbonate chips and excess dilute hydrochloric acid. The table below shows the data collected during the experiment.

Mass of flask and contents / grams Time / minutes 102.8 0 101.2 1 100.2 2 99.7 3 99.3 4 99.2 5 99.1 6 99.0 7 99.0 8 99.0 9

a) Place numbers in the spaces provided to show the order in which the steps below were performed. As the stopwatch is switched on, the calcium carbonate chips are transferred

to the conical flask so that the reaction starts. The mass of the whole setup is recorded every minute until three readings

have the same value. This is followed by placing the glass wool at the neck of the conical flask to

avoid acid from escaping the flask. Pour an excess amount of dilute hydrochloric acid into a conical flask. Place the conical flask filled with acid, a few calcium carbonate chips and a

piece of glass wool on a weighing balance to determine the initial mass. (5)

Page 8 of 12 Chemistry – Year 11 – Track 2 – 2021

Chemistry – Year 11 – Track 2 – 2021 Page 9 of 12 b) Fill in the labels of the diagram below.

(3)

c) Plot a graph using the data provided in the table. Place the mass of flask and contents on the y-axis and time on the x-axis. (5)

d) On your graph, sketch and label with an asterisk (*) a line to show what would happen if the same amount of calcium carbonate consisted of smaller chips. (3)

e) At which point in time did the reaction come to an end?

______(1)

f) Write a balanced chemical equation including state symbols to represent the reaction between calcium carbonate and hydrochloric acid.

______(3)

12) The annual global production of sulfuric acid is estimated at more than 270 million tonnes. Sulfuric acid is used heavily in the chemical industry to produce other substances.

a) Describe how sulfuric acid is produced from sulfur in the Contact Process which involves four steps. Your descriptions must include a balanced chemical equation for each step and any conditions required for Step 2.

i) Step 1: Production of sulfur dioxide.

______

______

______(3)

Page 10 of 12 Chemistry – Year 11 – Track 2 – 2021 ii) Step 2: Production of sulfur trioxide.

______

______

______

______(5)

iii) Step 3: Production of oleum. (Explain why this step is required.)

______

______

______

______(4)

iv) Step 4: Production of sulfuric acid.

______

______

______(3)

b) State what would be the effect of the following changes on the position of the equilibrium in Step 2 of the Contact Process.

i) Increase in pressure.

______(1)

ii) Use of the catalyst.

______(1)

c) Write a balanced chemical equation including state symbols to represent the reaction between ammonium hydroxide and sulfuric acid to produce ammonium sulfate.

______(3)

Chemistry – Year 11 – Track 2 – 2021 Page 11 of 12

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Page 12 of 12 Chemistry – Year 11 – Track 2 – 2021