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 halogens and halogen compounds.
(a) Deduce the number of electrons, neutrons and protons in one atom of the isotope of chlorine shown.[3]
\(_{17}^{37}\textrm{Cl }\)
number of electrons
number of neutrons
number of protons
(b) State why chlorine is used in water treatment.[1]
(c) Aqueous chlorine reacts with aqueous potassium iodide.
(i) Complete the chemical equation for this reaction. [2]
Cl2 + …..KI → …..KCl + I2
(ii) Explain in terms of the reactivity of the halogens why aqueous iodine does not react with aqueous potassium chloride.[1]
(d) The table shows some properties of four halogens.
(i) Complete the table by predicting:
-
- the boiling point of fluorine
- the density of liquid chlorine at its boiling point. [2]
(ii) Predict the physical state of chlorine at –105°C.
Give a reason for your answer.[2] [Total: 11]
Answer/Explanation
Ans:
(a) electrons: 17 (1)
neutrons: 20 (1)
protons: 17 (1)
(b) to kill bacteria (1)
(c)(i) 2 (KI) (1)
2 (KCl) (1)
(c)(ii) chlorine is more reactive than iodine / iodine is less reactive than chlorine
(d)(i) boiling point of fluorine:
values between – 40 and – 210 (inclusive of these values) (1)
density of chlorine:
values between 1.6 and 3.0 (inclusive of these values) (1)
(d)(ii) solid (1)
–105 °C is lower than the melting point / the melting point is above –105 °C (1)
Question
This question is about metals.
(a) State three general physical properties common to most metals.[3]
1
2
3
(b) Metals are often used in the form of alloys.
(i) State the meaning of the term alloy.[1]
(ii) Explain in terms of their properties why alloys are used instead of pure metals.[1]
(iii) Stainless steel is an alloy.
Give one use of stainless steel.[1]
(c) Place these metals in order of their reactivity with oxygen.
copper
magnesium
potassium
zinc
Put the least reactive metal first.[2]
(d) When 4.8g of magnesium reacts with excess oxygen, 8.0g of magnesium oxide is formed.
Calculate the minimum mass of magnesium needed to produce 24.0g of magnesium oxide.
minimum mass = g [1] [Total: 9]
Answer/Explanation
Ans:
a) 1 mark each for any three of:
-
- conduct electricity / conduct heat
- malleable
- ductile
- shiny / lustrous
- sonorous / rings when hit
(b)(i) mixture of metal with another element
(b)(ii) (alloy is) hard(er) / (more) resistant to corrosion / strong(er)
(b)(iii) cutlery / chemical plant / surgical equipment
(c) copper , zinc , magnesium , potassium (2)
if 2 marks not scored: 1 mark for one consecutive pair reversed
(d) 14.4 (g)