Question: How to calculate the H3O of a solution with a pOH of 5,3?
1. **State the problem.**
We need to find the hydronium ion concentration, $[H_3O^+]$, for a solution with $pOH = 5.3$.
2. **Use the formula.**
The key relationships are:
$$pH + pOH = 14$$
$$pH = -\log[H_3O^+]$$
First, find $pH$ from $pOH$.
3. **Find $pH$.**
$$pH = 14 - 5.3 = 8.7$$
4. **Convert $pH$ to $[H_3O^+]$.**
$$[H_3O^+] = 10^{-pH}$$
Substitute $pH = 8.7$:
$$[H_3O^+] = 10^{-8.7}$$
5. **Evaluate the concentration.**
$$[H_3O^+] \approx 2.0 \times 10^{-9}$$
6. **Final answer.**
The hydronium ion concentration is $$[H_3O^+] \approx 2.0 \times 10^{-9}$$ mol/L.