# What is pH in chemistry?

$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$
$p H$, literally, $\text{pouvoir hydrogeene}$ or $\text{power of hydrogen}$ is a measure of the concentration of hydrogen ion in aqueous solution. In precalculator days, the use of logartihmic tables greatly simplified complex calculation, which is why these scales were developed. There should be 2 logarithmic functions on your calculator, ${\log}_{10}$ and ${\log}_{e}$ or $\ln$.
You should be able to tell me the values of ${\log}_{10} 100$, ${\log}_{10} 1000$, and ${\log}_{10} 0.1$; these are all simple whole numbers.