# Electrolysis involving K+ and Li+ ions

Need clarification on Q31a) in the image. Possibly a dumb question but the book's answer might be wrong. The book says lithium ions will be reduced instead of potassium ions. How is this true when K+ ions are stronger oxidants?

Their answer for part d even reiterates that's Li+ will react in preference to K+ so I think I may be wrong...not sure how though

Thanks

• Who says K+ ions are stronger oxidants? It might seem so according to standard electrode potentials, but those only apply to water solutions. – Ivan Neretin Jun 1 '17 at 10:37
• How does a molten electrolyte change this? – Destudent Jun 1 '17 at 11:31
• everything is relative – Fl.pf. Jun 1 '17 at 12:18

$\ce{Li+}$ 's low standard reduction potential value applies to aqueous solutions only.
$\ce{Li+}$ has very high polarising power due to its small size (and in turn a high hydration energy). This is why $\ce{Li+}$ has a very low reduction potential compared to other alkali metals in aqueous solutions.