In aqueous solution, sulphuric acid ionizes in two steps:
H2 SO4 is very strong in water largely because of its first ionisation to H3O+ and HSO4–.
H2SO4(aq) +H2O(l)→ H3O+ (aq) + HSO4- (Ka1
HSO4- + H2O(l) → H3O+ +SO4-2 (Ka2
The ionisation of HSO4– to H3O– and SO42– is very small. That is why Ka2 < < Ka1,.