The pOH of a 0.0125 mol/L solution of sodium hypochlorite
To find the pOH of a solution, we need to know the concentration of hydroxide ions (OH-).
In the case of sodium hypochlorite (NaClO), it dissociates in water to form sodium ions (Na+) and hypochlorite ions (ClO-). However, sodium hypochlorite is a weak electrolyte, meaning it only partially dissociates in water.
The balanced chemical equation for the dissociation of sodium hypochlorite is:
NaClO(aq) -> Na+(aq) + ClO-(aq)
Since the compound only partially dissociates, the concentration of hydroxide ions (OH-) is not the same as the concentration of sodium hypochlorite. Instead, we need to find the concentration of hydroxide ions using the concept of mass balance.
The molar concentration of hydroxide ions (OH-) can be found by multiplying the molar concentration of sodium hypochlorite (NaClO) by the number of hydroxide ions produced for every one molecule of sodium hypochlorite.
In this case, the concentration of sodium hypochlorite is given as 0.0125 mol/L.
The balanced chemical equation shows that there is one hydroxide ion (OH-) produced for every one hypochlorite ion (ClO-) formed. Therefore, the molar concentration of hydroxide ions (OH-) is also 0.0125 mol/L.
The pOH of a solution can be found using the formula:
pOH = -log10[OH-]
Plugging in the molar concentration of hydroxide ions (OH-), we get:
pOH = -log10(0.0125) = 1.9
Therefore, the pOH of a 0.0125 mol/L solution of sodium hypochlorite is 1.9.