## Final 2012

Acidity $K_{a}$
Basicity $K_{b}$
The Conjugate Seesaw $K_{a}\times K_{b}=K_{w}$

Blake_Katsev_2E
Posts: 113
Joined: Wed Sep 21, 2016 2:57 pm

### Final 2012

why in question 8 is there only 3 sig figs?

Jared Faith 4E
Posts: 10
Joined: Wed Sep 21, 2016 2:57 pm

### Re: Final 2012

When finding pH, you apply sig fig rules after the decimal place. For example in question 8, there are 2 sig figs in 0.0037 M solution and in Ka=4.3x10^-7, so there should be 2 sig figs in your answer, that is after the integer value for pH.

So when you find the pH to be around 4 on the pH scale, you would then know to include 2 sig figs after the decimal point and get 4.30 (which looks like 3 sig figs even though the 2 we are interested in are behind the decimal).