determine the pH of 1.0 mol/L solution of aqueous sodium hypochlorite
To determine the pH of a solution of sodium hypochlorite (NaOCl), we need to calculate the concentration of hydroxide ions (OH-) in the solution.
The chemical formula for sodium hypochlorite is NaOCl. When it dissolves in water, it dissociates into sodium ions (Na+) and hypochlorite ions (OCl-). The water can also undergo autoprotolysis, where some water molecules act as both acid and base and produce hydronium ions (H3O+) and hydroxide ions (OH-).
The balanced equation for these reactions is:
NaOCl + H2O ⇌ Na+ + OCl- + H3O+
From the reaction, we can see that the reaction produces one hydroxide ion (OH-) for every hypochlorite ion (OCl-) formed.
Given that the concentration of sodium hypochlorite is 1.0 mol/L, the concentration of hydroxide ions will also be 1.0 mol/L. Therefore, the pH of the solution can be calculated using the formula:
pOH = -log10[OH-]
pOH = -log10(1.0) = -log10(1) = 0
Since pH + pOH = 14 (at 25°C), we can determine the pH using this relationship:
pH = 14 - pOH = 14 - 0 = 14
Therefore, the pH of a 1.0 mol/L solution of aqueous sodium hypochlorite is 14.