Answer :
Answer:
Ka = 6.02x10⁻⁶
Explanation:
The equilibrium that takes place is:
- HA ⇄ H⁺ + A⁻
- Ka = [H⁺][A⁻]/[HA]
We calculate [H⁺] from the pH:
- pH = -log[H⁺]
- [H⁺] = [tex]10^{-pH}[/tex]
- [H⁺] = 9.12x10⁻⁴ M
Keep in mind that [H⁺]=[A⁻].
As for [HA], we know the acid is 0.66% dissociated, in other words:
- [HA] * 0.66/100 = [H⁺]
We calculate [HA]:
- [HA] = 0.138 M
Finally we calculate the Ka:
- Ka = [tex]\frac{[9.12x10^{-4}]*[9.12x10^{-4}]}{[0.138]}[/tex] = 6.02x10⁻⁶