Hi, could you help me with this exercise, please?

"The pH of a 0.6 M solution of a weak acid is 4.0. What is the percentage of ionised acid?"

Thanks.

## calculation of ionisation percentage

**Moderators:** expert, ChenBeier, Xen

### calculation of ionisation percentage

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- ChenBeier
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**Posts:**983**Joined:**Wed Sep 27, 2017 7:25 am**Location:**Berlin, Germany

### Re: calculation of ionisation percentage

Calculate the Concentration of H+ of the acid from pH.

This value divide through the Concentration of the whole acid x 100% gives percentage of dissociation.

This value divide through the Concentration of the whole acid x 100% gives percentage of dissociation.

### Re: calculation of ionisation percentage

I did so:

pH= -log_10([H+])= 10^-4

%=((10^-4)/(0,6))*100=0,016

but I do not get the expected result (0.02%)

Should I round up?

pH= -log_10([H+])= 10^-4

%=((10^-4)/(0,6))*100=0,016

but I do not get the expected result (0.02%)

Should I round up?

The mind is like a parachute, it only works if it opens. -A. Einstein

- ChenBeier
- Distinguished Member
**Posts:**983**Joined:**Wed Sep 27, 2017 7:25 am**Location:**Berlin, Germany

### Re: calculation of ionisation percentage

0,0166 % is correct

### Re: calculation of ionisation percentage

thanks

The mind is like a parachute, it only works if it opens. -A. Einstein