The pH of a solution formed by dissolving 10^-5 moles of KOH in 100 litres solution is

a)6

b)6.7

c)7.3

d)8

To determine the pH of a solution formed by dissolving 10^-5 moles of KOH in 100 liters of water, we first need to understand how KOH behaves in solution. KOH is a strong base, meaning it completely dissociates in water to produce hydroxide ions (OH⁻). Let's break down the steps to find the pH.

Step 1: Calculate the concentration of KOH

We start by calculating the concentration of KOH in the solution. The formula for concentration (C) is:

C = n/V

• n = number of moles of solute (KOH) = 10^-5 moles
• V = volume of solution in liters = 100 L

Plugging in the values:

C = 10^-5 moles / 100 L = 10^-7 moles/L

Step 2: Determine the concentration of hydroxide ions

Since KOH completely dissociates, the concentration of hydroxide ions (OH⁻) will also be 10^-7 moles/L. This is crucial because the pOH of the solution can be calculated from the concentration of OH⁻.

Step 3: Calculate the pOH

The pOH is calculated using the formula:

pOH = -log[OH⁻]

Substituting the concentration of OH⁻:

pOH = -log(10^-7) = 7

Step 4: Relate pOH to pH

We know that pH and pOH are related through the equation:

pH + pOH = 14

Now, substituting the pOH we calculated:

pH + 7 = 14

Solving for pH gives:

pH = 14 - 7 = 7

Final Result

The pH of the solution formed by dissolving 10^-5 moles of KOH in 100 liters of water is 7. This indicates that the solution is neutral, which is consistent with the very low concentration of the base. Therefore, the correct answer is:

c) 7