Question

In the following acid–base reaction, classify each substance as the stronger acid, weaker acid, stronger base, or weaker base. HCN +HCO3- ---> <--- CN- + H2CO3. Which direction does equilibrium favor? a) to the left b) both directions c) to the right

Answer 1

lets compare the acid

H2CO3 and HCN are acting as acid

when H2CO3 loses H+, negative charge comes on Oxygen

when HCN loses H+, negative charge comes on Nitrogen

Since negative charge is more stable on Oxygen than Nitrogen due to electronegativity of Oxygen, H2CO3 will be more acidic

So,

H2CO3 is stronger acid. Its conjugate base HCO3- is weaker base

HCN is weaker acid. Its conjugate base CN- is stronger base

The equilibrium is shifted to weaker side always which is left

stronger acid: H2CO3

weaker acid: HCN

stronger base: CN-

weaker base: HCO3-

to the left