IGCSE CHEMISTRY - MID TEST PAPER

MID TEST SEMESTER 2 A.Y. 2022/2023

IGCSE CHEMISTRY

1. MULTIPLE CHOICE QUESTIONS

1. Which of the following statements about chemical equilibrium is correct?

1. Both the forward and backward reactions stop when equilibrium is reached.

2. The rate of forward reaction is equal to the rate of backward reaction at equilibrium

3. The concentrations of reactants and products are equal at equilibrium.

4. The concentrations of reactants and products are still varying at equilibrium.

2. Which of the following statements concerning the effect of catalysts on the reversible reactions is correct?

1. Catalysts increase the yield of products for reversible reactions.

2. Catalysts shorten the time for the reversible reactions to reach equilibrium by increasing both the rates of forward and backward reactions.

3. Catalysts shorten the time for the reversible reactions to reach equilibrium by increasing the rate of forward reaction and decreasing the rate of backward reaction.

4. Catalysts increase either the rate of forward reaction or the rate of backward reaction of reversible reactions.

3. Which of the following is a property of a reaction that has reached equilibrium?

1. The rate of forward reaction is higher than the rate of backward reaction.

2. The rate of forward reaction is equal to the rate of backward reaction.

3. The amount of products is equal to the amount of reactants

4. The amount of products is greater than the amount of reactants.

4. Consider the following system which is in equilibrium at a certain temperature:

2CO(g) + O2(g) <==> 2CO2(g)

If some CO(g) is added to the system, which of the following state is correct

1. there is a change in concentrations for both reactants and products

2. There is a change in concentration for the product only.

3. there is a no change in concentrations for both reactants and products

4. There is a change in concentrations for the reactants only.

5. Consider the following equilibrium reaction:

4HCl(g) + O2(g) <==>  2Cl2(g) + 2H2O(g)       ΔH = +ve

Which of the following changes will cause a shift in the equilibrium position of the above reaction?

(1) Adding Cl2(g)

(2) Removing O2(g)

(3) Adding a catalyst

1. (1) and (2) only

2. (2) and (3) only

3. (1), (2) and (3)

4. (1) and (3) only

6. Which of the following methods are beneficial to the industrial production of nitric acid?

3NO2(g) + H2O(l) <==> 2HNO3(aq) + NO(g)

(1)   Addition of nitrogen dioxide to the equilibrium mixture

(2)  Removal of nitrogen monoxide once it is formed

(3)  Increasing the pressure of the system at constant temperature

1. (1), (2) and (3)

2. (2) and (3) only

3. (1) and (3) only

4. (1) and (2) only

7. Consider the following equilibrium system:

H2(g) + I2(g) <==> 2HI(g)

What will be the change in the equilibrium position if the pressure of the system is increased?

1. The equilibrium position will remain unchanged.

2. The equilibrium position will shift to the left.

3. The change in equilibrium position cannot be determined.

4. The equilibrium position will shift to the right.

8. At high temperature, calcium carbonate decomposes to form calcium oxide and carbon dioxide according to the following equation:

CaCO3(s) <==> CaO(s) + CO2(g)    ΔH = +ve

Which of the following statements is/are correct?

(1) The addition of carbon dioxide at equilibrium will produce more calcium carbonate.

(2) A decrease in temperature will produce more carbon dioxide.

(3) An increase in pressure at equilibrium will produce more calcium carbonate.

1. (1) only

2. (2) only

3. (1) and (3) only

4. (2) and (3) only

9. Which of the following actions will cause the equilibrium position of the reaction to shift to the right?

NH4NO3(s) <==> N2O(g) + 2H2O(g)

1. Decreasing the volume of the container by four times.

2. Increasing the volume of the container by four times.

3. Adding N2O(g) to the equilibrium mixture.

4. Adding H2O(g) to the equilibrium mixture.

10. Consider the following chemical equilibrium:

I2(g) + H2(g)  <==>  2HI(g)   ΔH = - 9.6 kJ/mol

Which of the following changes would shift the equilibrium position of the above reaction to the right?

1. Removing hydrogen from the system

2. Adding a catalyst to the system

3. Increasing the pressure

4. Decreasing the temperature

11. Consider the following equilibrium reaction:

2N2O(g) + O2(g) <==> 4NO(g)

Which of the following changes will increase the amount of NO(g) in the equilibrium mixture?

(1) Adding N2O(g)

(2) Removing O2(g)

(3) Decreasing the volume of the container

1. (1) and (3) only

2. (2) and (3) only

3. (2) only

4. (1) only

12. As the temperature of a reaction is increased, the rate of the reaction increases because the..

1. reactant molecules collide less frequently 

2. reactant molecules collide less frequently and with greater energy per collision 

3. activation energy is lowered 

4. reactant molecules collide more frequently and with greater energy per collision 

13. The following reaction is at equilibrium. 

CF2Br2(g)  <==> CF2(g) + 2Br(g)    ΔH= 424 kJ mol–1 

How will the system respond if the temperature is decreased?

1. The reaction will shift to the left.

2. There will be no change to the equilibrium position.

3. The reaction will shift to the right.

4. more products

14. .

15. .

16. .

17. .

18.  At what time the reaction reached equilibrium?

1. t1

2. t2

3. t3

4. t4

19. For the reaction…

SO2 + O2  <=>  SO3

If the concentration of SO2 is increased, the equilibrium position of the reaction will shift __________

1. to the left

2. to the left and right 

3. to the right

4. neither left nor right

20. For the reaction...

N2 (g) +  3 H2 (g) <=> 2 NH3 (g)

If the pressure in the system is increased,  which substance(s) will increase in concentration?

1. N2  (as 2 mol gas  → 4 mol gas)

2. N2 and H2 (as 2 mol gas  → 4 mol gas)

3. H2 (as 2 mol gas  → 4 mol gas)

4. NH3 (as 4 mol gas  → 2 mol gas)

21. Consider the following reaction:

2SO2(g) + O2(g) <=> 2SO3(g):  ΔΗ = - 197 kJ mol -1

Which of the following will NOT shift the equilibrium position to the right?

1. Adding more O2

2. increasing the pressure

3. Adding a catalyst

4. Lowering the temperature

22. What are the two factors to look for when determining if the reaction is at equilibrium?

1. Forward reaction rate is faster than the reverse and concentrations are equal

2. Forward and reverse reaction rates are equal and concentration is equal

3. Forward and reverse reaction rates are equal and concentration is constant

4. Forward reaction rate is faster than the reverse and concentration is equal

23. When a negatively charged ion reaches the positively charged electrode...

1. It can lose an electron to become a neutral atom

2. It gains an electron to become a negative ion

3. It can lose an electron to become a positive ion

4. It gains an electron to become a neutral atom

24. Electrolysis of the following electrolytes (using inert electrodes) give the same product at the cathode except

1. concentrated potassium hydroxide

2. aqueous sodium chloride

3. dilute sulfuric acid

4. aqueous copper (II) sulphate

25. During the electrolysis of a CONCENTRATED CuSO4(aq)  the product at the CATHODE is:

1. H2( g )

2. O2( g )

3. SO2( g )

4. Red brown deposit Cu(s)

26. The diagram shows the electrolysis of a molten compound X.

1. lead(ii)bromide

2. sodium fluoride

3. Sodium chloride

4. Copper (II) Chloride 

27. At cathode occurs....

1. Reduction

2. Oxidation

3. redox

4. nothing happen

28. What is the charge on an anode and the type of element formed at such an electrode?

	Charge on anode	Type of element formed
A.	Negative	Metal
B.	Negative	Non-metal
C.	Positive	Metal
D.	Positive	Non-metal

1. letter C

2. letter D

3. letter A

4. letter B

29. Is the positive electrode

1. cathode

2. anode

3. cation

4. Anion

30. The experiment shown is used to test potassium bromide crystals.

The lamp does not light.

Distilled water is then added to the beaker and the lamp lights.

Which statement explains these results?

1. Oppositely charged ions are free to move in the solution when potassium bromide dissolves.

2. Electrons are free to move in the solution when potassium bromide dissolves.

3. Metal ions are free to move when potassium bromide melts.

4. Metal ions are free to move when potassium reacts with water.

31. Which statement about conduction of electricity is correct?

1. Electricity is conducted in a metal wire by ions.

2. Electricity is conducted in a molten electrolyte by electrons.

3. Electricity is conducted in aqueous solution by electrons.

4. Electricity is conducted in an acid solution by ions.

32. Sodium sulphate solution is electrolysed using carbon electrodes. What is the product formed at the cathode and anode respectively?  

1. Hydrogen,  Sulphur dioxide

2. Oxygen, Hydrogen

3. Hydrogen,  Oxygen

4. Sodium,  Oxygen

33. In the experiment shown in the diagram, the bulb lights and a gas is produced at each electrode.

What is X?

1. ethanol

2. aqueous copper(II) sulfate

3. concentrated aqueous sodium chloride

4. molten lead bromide

34. The diagram shows the electrolysis of a concentrated aqueous solution containing both copper(II) ions and sodium ions. 

Which metal is deposited at the negative electrode and why?

1. sodium, because copper is less reactive than hydrogen

2. copper, because copper is more reactive than hydrogen

3. sodium, because copper is more reactive than sodium

4. copper, because copper is less reactive than sodium

35. The apparatus shown below was set up to copper plate the metal spoon.

The experiment did not work.

What was the mistake in the apparatus?

1. The copper electrode should all be in the solution.

2. Dilute sulphuric acid should be used as the electrolyte.

3. A variable resistor should be included in the electrical circuit.

4. The spoon should be the negative electrode.

36. Which of the following does NOT contain free ions?

1. Aqueous ammonia

2. Aqueous hydrogen chloride

3. Solid potassium nitrate

4. Molten potassium chloride

37. What are the ions present in water?

1. H and OH

2. H+ and OH-

3. H2 and O

4. H2O

38. .

39.  .

40. .

41. Ammonia is manufactured by reacting hydrogen with nitrogen in the Haber process. Which row describes the sources of hydrogen and nitrogen and the conditions used in the manufacture of ammonia in the Haber process?

42. Limestone is an important material with many uses. Limestone is heated to produce ......1...... and carbon dioxide. This reaction is called ......2...... . Which words correctly complete gaps 1 and 2?

43. Ammonia is manufactured by the Haber Process. N2(g) + 3H2(g) < == > 2NH3(g) The forward reaction is exothermic. Which conditions maximise the yield of ammonia?

44. Which row shows the conditions used in the Contact process?

B . STRUCTURED QUESTIONS

1. Chromium is a silver-coloured metal.

The diagram shows how a copper spoon can be electroplated with chromium.

(a) How to construct this electroplating? complete the following:

      (i) what is made as the negative electrode?

      (ii) what is made as the positive electrode?

      (iii) what is made as the electrolyte?

                                                                                                              [3]

(b) Give one observation that is made during the electroplating process.  [1]

(c) Suggest one reason why metal objects are electroplated. [1]

(d) write the ionic equation at each electrode

     (i) cathode:

     (ii) anode:

                                                                                                   [2]

[Total: 7]

2. Dilute sulfuric acid can be electrolysed using the apparatus shown.

(a) State the products of this electrolysis at:

      the positive electrode (anode) :

      the negative electrode (cathode):                                                          [2]

(b) What observation is made at the electrodes?                                         [1]

(c) Suggest one reason why graphite is used for the electrodes rather than magnesium.  [1]

                                                                                                                           [Total: 4]

3. Ethanoic acid is manufactured by the reaction of methanol with carbon monoxide.

An equilibrium mixture is produced.

CH3OH(g) + CO(g) ⇌ CH3COOH(g)

(a) State two characteristics of an equilibrium.

1 ......................................................................................................................................

2 ...................................................................................................................................... [2]

The purpose of the industrial process is to produce a high yield of ethanoic acid at a high rate of reaction.

The manufacture is carried out at a temperature of 300 °C.

The forward reaction is exothermic.

Use this information to state why the manufacture is not carried out at temperatures:

(b)

• below 300 °C

...........................................................................................................................................

• above 300 °C

........................................................................................................................................... [2]

(c) Suggest which of the following metals is a suitable catalyst for the reaction. Give a reason for

your answer. 

aluminium calcium cobalt magnesium potassium

suitable catalyst ..............................................................................................................

reason ............................................................................................................................. [2]