Metals above carbon in the reactivity series
4 marks · NormalScandium is a metal above carbon in the reactivity series. It can be extracted from its oxide by heating with calcium. Use your knowledge of the reactivity series to answer the questions.
Explain why calcium can be used to extract scandium from its oxide.
Suggest one reason, other than expense, why this method might not be widely used for large-scale scandium extraction.
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.
Show answer
(a) Calcium is above scandium in the reactivity series, so it is more reactive and can reduce scandium oxide by removing its oxygen.
(b) The reaction might produce impurities, could be dangerous due to highly reactive calcium, or may have a low yield/efficiency.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States calcium is more reactive than scandium / higher in reactivity series.
B2 (a) · 1 mark · States calcium can reduce the oxide by removing oxygen from scandium oxide.
B3 (b) · 1 mark · Gives a valid reason: impurity formation, safety/danger issue, or inefficiency.
B4 (b) · 1 mark · Explanation of why this would limit large-scale use (e.g., unsafe, unreactive, or not practical for industry).
Worked solution
a) Calcium can be used because it is more reactive than scandium and can remove oxygen from scandium oxide, reducing it to scandium metal.
b) The method may create impurities in scandium, could be unsafe because calcium is very reactive, or may not be effective for large-scale production due to low yield.