If pH=1.65, what is [H_3O^+]?

1 Answer
Sep 13, 2017

[H^+] or [H_3O^+]=0.0224*mol*L^-1

Explanation:

For the equilibrium,

2H_2O rightleftharpoonsH_3O^+ + HO^-...

alternatively, H_2O rightleftharpoons H^+ + HO^-

K_"eq"=[H_3O^+][HO^-]=10^-14 under standard conditions.....

And we take log_10 of BOTH SIDES, and gets....

log_10[H_3O^+]+log_10[HO^-]=log_10(10^-14)=-14

underbrace(-log_10[H_3O^+])_(pH+)underbrace(-log_10[HO^-])_(pOH)=+14

And so pH+pOH=14, under standard conditions, the which we assume.

And thus for [H]^+/[H_3O^+], we take 10^(-1.65)*mol*L^-1=0.0224*mol*L^-1.

What is [HO^-] for this solution?