past papers

Question 1

before electrolysis the mass of each electrode is determined, what should be done to the electrodes before their masses are determined?

Answer 1

An explanation linking
• (electrodes) cleaned (using emery paper) (or similar) (1)
• to remove {surface oxide / grease / impurities} (1)

Question 2

explain the meaning of the term weak acid.

Answer 2

An explanation linking
• partially {dissociated / ionised} (1)
• {concentration of H+ ions lower / fewer H+ ions}
than expected (1)