Question

what is the ph of the 0.00125 m naoh solution? remember that naoh is a strong base. a) ph = -0.00125 b) ph = poh -14 = 2.9 - 14 = -11.1 c) ph = 0.00125 d) ph = 14 - poh = 14 - 2.9 = 11.1

Explanation:

Step1: Find $[\text{OH}^-]$ concentration

Since NaOH is a strong base, it dissociates completely: $\text{NaOH}
ightarrow \text{Na}^+ + \text{OH}^-$, so $[\text{OH}^-] = 0.00125\ \text{M}$.

Step2: Calculate pOH from $[\text{OH}^-]$

$\text{pOH} = -\log_{10}[\text{OH}^-] = -\log_{10}(0.00125) \approx 2.9$

Step3: Calculate pH from pOH

Use the relation $\text{pH} + \text{pOH} = 14$, so rearrange to $\text{pH} = 14 - \text{pOH}$.
$\text{pH} = 14 - 2.9 = 11.1$

Answer:

d) $\text{pH} = 14 - \text{pOH} = 14 - 2.9 = 11.1$