Question

Why is NaHCO3 a base?

(I need someone to explain it using the ka values)

H2CO3 <--> HcO3- + H+ ka = 4.3x10^-7
HCO3- <--> CO3^2- + H+ ka = 5.61x10^-11

if I underestand correctly, the kb for the second equation is greater than the ka. Thus the reaction will not proceed forward, but rather produce more HCO3-. This is a basic tendency. Why is it more powerful than the first reaction?

Answer 1

NaHCO3 (sodium bicarbonate) is a base because it can accept a proton from water, forming bicarbonate ion (HCO3-). The second reaction, where HCO3- forms more HCO3- ions, is more basic than the first reaction.

Step-by-step explanation:

NaHCO3 (sodium bicarbonate) is classified as a base because it can accept a proton (H+) from water, forming bicarbonate ion (HCO3-). The dissociation of sodium bicarbonate in water can be represented by the following equations:
H2CO3 <--> HCO3- + H+ (Ka = 4.3x10^-7)
HCO3- <--> CO3^2- + H+ (Ka = 5.61x10^-11)

The ka values indicate the extent of ionization of the acid and the relative strength of the acid. In this case, the second reaction has a smaller Ka value, indicating that it ionizes less and forms more HCO3-. This makes the second reaction more basic compared to the first reaction.

Answer 2

An aqueous solution of sodium bicarbonate would be having a pH value above 7, whatever its concentration. NaHCO3 is a salt of a weak acid, H2CO3, and a strong base, NaOH. Since carbonic acid is a weak acid, it remains undissociated.