# The pH of a juice drink is 2.8. How do you find the concentration of hydrogen ions in the drink, in simplest form?

$2 \times {10}^{- 3} M$
In the simplest terms, to calculate $\left[{H}^{+}\right]$ from $p H$, you use the equation $\left[{H}^{+}\right] = {10}^{- p H}$; $10$ to the power of the negative of the $p H$. So, $\left[{H}^{+}\right] = {10}^{- 2.8} = 2 \times {10}^{- 3} M$ (appropriate number of significant digits).