ph of a solution is 4 .if 50 ml of the solution is diluted with water to get 100ml. what is the ph of new solution

To determine the pH of the new solution after dilution, we need to understand how dilution affects the concentration of hydrogen ions in a solution. The pH scale measures the acidity or basicity of a solution, and it is defined as the negative logarithm of the hydrogen ion concentration. Let's break this down step by step.

Initial Conditions

The initial solution has a pH of 4. This means that the concentration of hydrogen ions \([H^+]\) can be calculated using the formula:

[H⁺] = 10^-pH

Substituting the pH value:

[H⁺] = 10^-4 = 0.0001 M

Volume and Dilution

You have 50 mL of this solution, which you will dilute to a total volume of 100 mL. When you dilute a solution, the number of moles of solute remains the same, but the volume increases, which decreases the concentration.

Calculating Moles of Hydrogen Ions

First, we calculate the number of moles of hydrogen ions in the original 50 mL solution:

Moles of H⁺ = Concentration × Volume

Moles of H⁺ = 0.0001 M × 0.050 L = 0.000005 moles

New Concentration After Dilution

After dilution, the total volume is now 100 mL (or 0.1 L). The concentration of hydrogen ions in the new solution can be calculated as follows:

New [H⁺] = Moles of H⁺ / New Volume

New [H⁺] = 0.000005 moles / 0.1 L = 0.00005 M

Finding the New pH

Now that we have the new concentration of hydrogen ions, we can find the new pH:

New pH = -log([H⁺])

New pH = -log(0.00005)

Calculating this gives:

New pH ≈ 4.3

Summary

After diluting the original solution with water, the pH of the new solution is approximately 4.3. This increase in pH indicates that the solution has become less acidic due to the dilution effect, which is a common outcome when mixing an acidic solution with water.