Question

Is the hydrogen ion concentration of a ph 3.8 solution higher or lower than the solution with a ph of 6.2

Answer 1

You can work out the concentration of H+ ions (denoted as [H+]) easily on a calculator if you know the pH, which you do. The easiest way to work out [H+] is to do $10^{-pH}$. In your case, the maths here would be $10^{-3.8}$, which gets you an answer of 1.58x$10^{-4}$, or 0.000158. For 6.2 it would be $10^{-6.2}$, which gives you 6.31x$10^{7}$, or 0.00000063. As you can see, the concentration of H+ ions is greater in pH 3.8.

To put it simply, the [H+] decreases the higher up the pH scale you go, and increases as you go lower, but now you know the maths to work it out for yourself too.