h2so4 forms two series of salts why
Answers
Sulphuric acid is a dibasic acid that dissociates in 2 stages.
H2SO4 <=> H+ and (HSO4)- — (Ka1)
HSO4- <=> H+ and (SO4)2- —(Ka2)
Ka2 is slightly lower than Ka1, so under the right conditions, you may get (HSO4)- salts.
An reaction between 1 mole of H2SO4 and 1 mole of NaOH will look like this. Both H2SO4 and NaOH are strong acid and bases respectively, so the reaction will go to completion, not hang around at (HSO4)-, since Ka2 is still quite high.
0.5H2SO4 and NaOH →0.5Na2SO4 and H2O
The excess 0.5 moles of H2SO4 will exist as an equilibrium of (HSO4)- and (SO4)2-.
How can I get more (HSO4)- instead of (SO4)2-? The one solution I can think of is a bit ironic: increase the concentration of (SO4)2-. This will shift the equilibrium to the left for the Ka2 reaction.