Chemistry · May / June 2025 · Paper 42 · Question 3
0620
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This question is about electrolysis.
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3(a)[3]
M1 ionic
M2 molten
M3 in aqueous solution
3(b)(i)[1]
increase
3(b)(ii)[1]
becomes paler blue
or
becomes colourless
3(b)(iii)[1]
bubbles
3(b)(iv)[3]
4OH– → 2H2O + O2 + 4e-
M1 any negatively charged OH species losing electrons
OR
H2O + O2 as only products (other than electrons) on RHS
M2 any negatively charged OH species losing electrons
AND
H2O + O2 as only products (other than electrons) on RHS
M3 correct equation
3(c)(i)[1]
increases
3(c)(ii)[1]
no change
3(d)(i)[1]
bauxite
3(d)(ii)[1]
cryolite
3(d)(iii)[2]
M1 anodes or carbon / graphite react with oxygen / O2
M2 (form) carbon dioxide
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