Carbon dioxide and global warming: the greenhouse effect
5 marks · HardA student heats a sample of iron(II) carbonate to investigate the formation of carbon dioxide gas.
Write the balanced chemical equation, including state symbols, for the thermal decomposition of iron(II) carbonate.
State the type of reaction taking place.
Describe one observation the student would make as the reaction occurs.
Name the gas formed in this reaction.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) \ce{FeCO3(s) -> FeO(s) + CO2(g)} · must show Balanced equation: FeCO3(s) -> FeO(s) + CO2(g), State symbols correct
(b) Thermal decomposition · must show Thermal decomposition
(c) The solid changes from pale green to black; or a gas is released; or the solid darkens in colour. · must show Colour change (green to black/grey), Gas evolved (bubbles/fizzing)
(d) Carbon dioxide · must show CO2, Carbon dioxide
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correct formulae and products in the equation
B2 (a) · 1 mark · Correct state symbols for all species
B3 (b) · 1 mark · States 'thermal decomposition' as the type of reaction
B4 (c) · 1 mark · Describes a correct observation (e.g. colour change green to black/grey, or gas given off)
B5 (d) · 1 mark · Names the gas as 'carbon dioxide' or 'CO2'
Worked solution
a) The balanced equation is:
b) The type of reaction is called thermal decomposition.
c) As the iron(II) carbonate is heated, the pale green solid turns black (iron(II) oxide forms), and a gas is released.
d) The gas formed is carbon dioxide (CO2).