AQA A Level chemistry tests

How would using a metal carbonate or Mg with SO2(aq) produce slower effervescence and with SO3(aq) faster effervescence please?
And with universal indicator why would SO2 be orange red and SO3 just red?

Reply 1

TypicalNerd

Original post by anon25x

SO2 (aq) is H2SO3 - a weak acid
SO3 (aq) is H2SO4 - a strong acid

As H2SO3 is a weak acid, there are few H^+ ions in the solution at any given time, so the frequency of successful collisions per unit time is low and the rate isn’t enormous.

As H2SO4 is a strong acid, there are many H^+ ions in the solution (initially), so the frequency of successful collisions per unit time is sizeable and the rate (at least initially) will be noticeably very rapid.