Question

If the hydrogen ion concentration of a solution is `10^-10`M is the solution acidic, alkaline, or neutral?

Answer 1

The solution is BASIC............

Explanation:

In water the following equilibrium applies under standard conditions:

`2H_2O(l) rightleftharpoonsH_3O^(+) +HO^(-)`, and also.....

`K_w=[H_3O^+][HO^-]=10^-14` under standard conditions at `298*K`.

We can take `log_10` of both sides...........

`log_10K_w=log_10[H_3O^+]+log_10[HO^-]=log_10(10^-14)=-14`.

And thus on rearrangement,

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

And thus our defining relationship..........

`pH+pOH=14`

And we gots `[H_3O^+]=10^(-10)*mol*L^-1`

And thus `pH=-log_10{10^-10}=-(-10)=10`

`pOH=14-pH=14-10=4`

And thus (finally!)

`[HO^-]=10^-4*mol*L^-1=0.0001*mol*L^-1`.

And since `[HO^-]` is `10^6` times greater than `[H_3O^+]` the solution is BASIC.

Got that? (I didn't realize I could go on for so long!)