Metals below carbon in the reactivity series
3 marks · NormalExplain why metals below carbon in the reactivity series, such as zinc and iron, are extracted by reduction with carbon, but metals above carbon are not.
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Must show: comparison of positions in the reactivity series, reference to ability of carbon to reduce their oxides, reason carbon cannot reduce oxides of more reactive metals
Also accept: Reference to energy requirements or need for electrolysis as part of explanation.
Common mistakes: Saying only 'carbon is cheaper'; Omitting reference to reactivity or position in series
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Marking points
B1 · 1 mark · Identifies that zinc and iron are below carbon in the reactivity series.
B2 · 1 mark · Explains carbon can reduce their oxides to the metal.
B3 · 1 mark · States metals above carbon are too reactive for carbon to reduce their oxides; electrolysis required.
Worked solution
Metals such as zinc and iron are below carbon in the reactivity series, so carbon is more reactive and can reduce their oxides by removing oxygen. Metals above carbon in the reactivity series form much more stable oxides, and carbon is not reactive enough to remove the oxygen. These metals must be extracted using electrolysis.