Question
(a) Sulfur dioxide is a pollutant in the air.
(i) State one source of sulfur dioxide in the air………………………………………………………………………………………………………………………. [1]
(ii) Sulfur dioxide is oxidised to sulfur trioxide in the air.
Oxides of nitrogen act as catalysts for this reaction.
What is meant by the term catalyst?…………………………………………… [1]
(iii) Sulfur trioxide dissolves in rainwater to form acid rain.
Which one of the following pH values could be the pH of acid rain?
Draw a circle around the correct answer.[1]
pH 4 pH 7 pH 9 pH 13
(iv) State one adverse effect of acid rain on buildings.
……………………………………………………………………………………………………………………… [1]
(b) Sulfur dioxide melts at –73 °C and boils at –10 °C.
What is the physical state of sulfur dioxide at –20 °C?
Explain your answer…………………………………………………………………………………………………………………………….. [2]
(c) Excess sulfuric acid reacts with ammonia to make a salt which can be used as a fertiliser.
State the name of the salt formed when excess sulfuric acid reacts with ammonia…………………………………………………………………………………………………………………………….. [1]
(d) The table shows some observations about the reactivity of four metals with dilute sulfuric acid.
Use the information in the table to put the four metals in order of their reactivity. Put the least reactive metal first.
▶️Answer/Explanation
Ans:
(a)(i) burning fossil fuels / volcanoes / heating (sulfide) ores
(a)(ii) substance which speeds up a reaction / substance which increases the rate of reaction
(a)(iii) pH4
(a)(iv) erodes buildings (made of carbonate rocks) / wears away buildings (made of carbonate rocks) / reacts with mortar / corrodes iron
work / corrodes metal
(b) liquid (1)
–20 °C is between the melting and boiling point / –20 °C is above melting point but lower than boiling point (1)
(c) ammonium sulfate
(d) tungsten < nickel < iron < magnesium (2)
if 2 marks not scored 1 mark for one consecutive pair reversed
Question
This question is about acids, bases and salts.
(a) Sodium hydroxide is a base.
(i) Name the products formed when sodium hydroxide reacts with dilute nitric acid.[2]
(ii) Describe the effect of sodium hydroxide on a named indicator.[2]
(iii) Complete the word equation for the reaction of sodium hydroxide with ammonium chloride.
(b) Describe how to prepare pure, dry crystals of the salt zinc sulfate from an aqueous solution of zinc sulfate.[2]
(c) The rate of reaction of zinc powder with dilute sulfuric acid is found by measuring the increase in volume of hydrogen gas produced as time increases.
Describe the effect, if any, of each of the following on the rate of this reaction.
-
- The reaction is carried out with large pieces of zinc instead of zinc powder.
All other conditions stay the same.
-
- The reaction is carried out using a catalyst.
All other conditions stay the same.
-
- The reaction is carried out with dilute sulfuric acid of a lower concentration.
All other conditions stay the same. [3] [Total: 11]
Answer/Explanation
Ans:
(a)(i) sodium nitrate (1)
(and) water (1)
(a)(ii) named suitable indicator e.g. methyl orange / litmus (1)
correct colour in alkali e.g. blue (for litmus) / yellow (for methyl orange) (1)
(a)(iii) ammonia (1)
sodium chloride (1)
(b) 1 mark each for any two of:
-
- evaporate to point of crystallisation / heat to point of crystallisation / evaporate some of the water and leave (1)
- filter crystals / pick out crystals (1)
- dry with filter paper / dry in drying oven
(c) large pieces: (rate) decreases / (reaction gets) slower (1)
catalyst: (rate) increases / (reaction gets) faster (1)
lower concentration: (rate) decreases / (reaction gets) slower (1)
Question
This question is about zinc and compounds of zinc.
(a) Zinc is a metal.
Give three physical properties of metals.[3]
1
2
3
(b) Zinc reacts with phosphorus to form zinc phosphide, Zn3P2.
Complete the equation for this reaction.[2]
Zn + P → Zn3P2
(c) Molten zinc chloride is electrolyzed.
The incomplete apparatus is shown.
(i) Complete the diagram by:[2]
completing the circuit to show the wires and power pack
labelling the anode.
(ii) Name the products formed at each electrode.[2]
positive electrode
negative electrode
(d) Zinc chloride reacts with water as shown. The solution formed is acidic.
\(ZnCl_{2}+2H_{2}O\rightleftharpoons Zn\left ( OH \right )_{2}+2HCl\)
(i) State the meaning \(\rightleftharpoons\) of the symbol .[1]
(ii) Choose the pH value which is acidic.
Draw a circle around your chosen answer.[1]
pH 3 pH 7 pH 9 pH 14
(e) A compound of zinc has the formula ZnC4H10.
Complete the table to calculate the relative molecular mass of ZnC4H10.
relative molecular mass = [2] [Total: 13]
Answer/Explanation
Ans:
(a) 1 mark each for any three of:
-
- conduct electricity OR conduct heat (1)
- malleable (1)
- ductile (1)
- shiny / lustrous (1)
(b) 3 (Zn) (1)
2 (P) (1)
(c)(i) wires leading from each side of power pack or battery to the electrodes (1)
positive electrode labelled anode (1)
(c)(ii) positive electrode: chlorine (1)
negative electrode: zinc (1)
d)(i) reversible reaction
(d)(ii) pH 3
(e) 123 (2)
if two marks not scored, allow 1 mark for C = 4 x 12 / 48 OR H = 1 x 10 / 10