Equal volumes of solution of `pH=6and pH=8` are mixed. What will be the pH of resulting mixture?

Answer

To find the pH of the resulting mixture when equal volumes of solutions with pH 6 and pH 8 are mixed, we can follow these steps:

### Step 1: Understand the pH Scale
The pH scale is a logarithmic scale that measures the concentration of hydrogen ions (H⁺) in a solution. The formula to calculate pH is:
\[ \text{pH} = -\log[\text{H}^+] \]

### Step 2: Calculate the H⁺ Concentration for Each Solution
1. For the solution with pH 6:
\[ [\text{H}^+] = 10^{-6} \, \text{M} \]

2. For the solution with pH 8:
\[ [\text{H}^+] = 10^{-8} \, \text{M} \]

### Step 3: Mix the Solutions
When equal volumes of these two solutions are mixed, the total volume doubles, and we can calculate the new concentration of H⁺ ions in the mixture.

- The total concentration of H⁺ ions from both solutions:
\[ \text{Total } [\text{H}^+] = [\text{H}^+]_{pH 6} + [\text{H}^+]_{pH 8} = 10^{-6} + 10^{-8} \]

### Step 4: Calculate the New H⁺ Concentration
Since we are mixing equal volumes, the concentration of H⁺ ions in the resulting mixture will be:
\[ [\text{H}^+]_{\text{mixture}} = \frac{10^{-6} + 10^{-8}}{2} \]
Calculating this gives:
\[ [\text{H}^+]_{\text{mixture}} = \frac{10^{-6} + 0.01 \times 10^{-6}}{2} = \frac{1.01 \times 10^{-6}}{2} = 0.505 \times 10^{-6} = 5.05 \times 10^{-7} \, \text{M} \]

### Step 5: Calculate the pH of the Mixture
Now we can find the pH of the resulting mixture:
\[ \text{pH}_{\text{mixture}} = -\log(5.05 \times 10^{-7}) \]

Using a calculator:
\[ \text{pH}_{\text{mixture}} \approx 6.30 \]

### Final Answer
The pH of the resulting mixture is approximately **6.30**.

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