Question #bd6c1
1 Answer
I usually don't follow this rule, although I admit I should, but pH and pOH values should take into account the number of sig figs given for the concentration of
However, there's a little trick to remember. For pH and pOH values, only the digits after the decimal count as being significant.
In your example, you have
You would be tempted to say that, rounded to three sig figs, the answer should be
You need to take 3 sig figs after the decimal, so the answer becomes
Another example. If you have
But again, you'd be wrong because you actually need to have 1 dig fig after the decimal, like this
This is just a result of how sig figs are calculated for logs and antilogs. Read more about that here (towards the bottom of the page)
http://web.campbell.edu/faculty/fetterman/Significant%20Figures.htm
and here