Final answer:
To determine the pH of a solution that is 3.85% KOH by mass, we need to calculate the concentration of KOH in the solution. The concentration of KOH is 0.0987 mol/L, which gives a pH of 1.01.
Step-by-step explanation:
To determine the pH of a solution that is 3.85% KOH by mass, we need to calculate the concentration of KOH in the solution. First, we can convert the mass percent to grams of KOH by assuming we have 100 grams of the solution. This gives us 3.85 grams of KOH. Since the density of the solution is 1.01 g/mL, the volume of the solution is 3.85 mL (3.85 grams / 1.01 g/mL).
Next, we need to convert the volume of the solution to liters to find the concentration of KOH in mol/L. Since there are 39.1 grams of KOH in a mole, we can convert 3.85 grams to 0.0987 moles (3.85 grams / 39.1 g/mol). Dividing this by the volume of the solution in liters gives us a concentration of 0.0987 mol/L.
The pH of a solution can be calculated using the equation pH = -log[H+]. Since KOH is a strong base, it completely dissociates in water to give OH- ions. The concentration of OH- ions is the same as the concentration of KOH, which is 0.0987 mol/L. Taking the negative logarithm of this concentration gives us a pH of 1.01.