CHEMISTRY COMMUNITY

In high school, I was taught to add a sig fig when you take the -log to calculate the pH; however, there have been different things said about sig figs for this class regarding this topic. What is the expected rule for sig figs when taking the log that I should follow?

Based on my understanding it's roughly the same as what the problem gives. So if the concentration was 4.20 x 10^-6 mol then the pH would be 5.38.

Sig figs for pH are only calculated after the decimal. For example, a ph of 4.52 would have 2 sig figs.

I personally just round off to sig figs at the very end of the problem.

I posted a photo further specifying significant figures for logs. But as it states on dr Lavelles PDF of “More on Significant figures” how ever many significant figures in the number your calculating is how ever many significant figures you have after the calculation.