H2SO4 vs H2CO3

[Joussie Camacho 4I]

If both H2SO4 and H2CO3 are polyprotic acids, why is sulfuric acid a strong acid but carbonic acid is not? Is it because although carbonic acid CAN donate its 2 H+s, it's very unlikely to? Why then does sulfuric readily donate one H+ to make HSO4- ?

[sameeksha_panda_3h]

I'm not completely sure, but HSO4- is probably a more stable conjugate bas than HCO3-! In addition to other factors, the stability of the conjugate can contribute to concentration of H+ in a solution.

[Ahmed Mahmood 4D]

Because HSO4- has sulfur, which has a greater electronegativity than carbon, the anion is more stable (Due to electron delocalization) and thus its acid is stronger.

[Nicole Elhosni 2I]

In class, Dr. Lavelle pointed out though that both SO4 2- and CO3 2- have resonance, which means their electrons are delocalized and the anion will be stable. Doesn't this make the acid a strong acid then?

[Shutong Hou_1F]

H2SO4 is more readily to donate H atoms than H2CO3 because S is more electronegative by having more protons (in 4th period, while C is in 3rd period) and thus have more electron density withdrawing power.