Question

which option correctly shows the concentration of h₃o⁺ ions in pure water (ph 7)? (1 point)
7 mol/l
1.0×10⁻¹⁴ mol/l
1.0×10⁻⁷ mol/l
14 mol/l

Explanation:

Step1: Recall pH formula

The formula for pH is $pH = -\log_{10}[H_3O^+]$, where $[H_3O^+]$ is the concentration of hydronium ions.

Step2: Rearrange formula for $[H_3O^+]$

We can rewrite the formula as $[H_3O^+]=10^{-pH}$.

Step3: Substitute pH value

Given $pH = 7$, substituting into the formula gives $[H_3O^+]=10^{-7}\ mol/L = 1.0\times10^{-7}\ mol/L$.

Answer:

$1.0\times10^{-7}\ mol/L$ (corresponds to the third - option from the list in the question)