Question

Preparas una solución 0.25 m de NaOH, si tomas una muestra de 30 ml de esta solución y lo llevas a un aforo de 500 ml ¿cuál será su pH y su pOH final?

Answer 1

Answer:

pOH = 1.82

pH = 12.18

Explanation:

pH is defined as - log [H⁺] while pOH is defined as - log [OH⁻]

When you take 30mL of a solution 0.25M of NaOH and complete to 500mL the concentration of NaOH is:

0.25M of NaOH ₓ (30mL / 500mL) = 0.015M of NaOH. As NaOH is a strong base and dissociates completely, the concentration of OH⁻, [OH⁻] is  0.015M. Thus, pOH is:

pOH = - log [0.015M] = 1.82

As 14 = pOH + pH, pH of the solution is:

pH = 14 - 1.82

pH = 12.18