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

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Answer 1 · 2017-06-12T17:50:04

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

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!)