# How do I find the "H"_3"O"^+ concentration of compounds?

Using the $\text{pH}$ value of the compounds.
The $\text{pH}$ of a compound shows how many ${\text{H"_3"O}}^{+}$ ions it forms in water. The higher that value, the more acidic it is.
An easy way to determine $\text{pH}$ is using universal indicator.