Equal volumes of two solutions with pH=4 and pH = 10 are mixed. The pH of resulting solution will be

Options

A. 3.5
B. 6.1
C. 7
D. 14

Explanation

To find the pH of the resulting solution when equal volumes of two solutions with pH 4 and pH 10 are mixed, we can follow these steps:

### Step 1: Determine the concentration of H⁺ ions in the solution with pH 4.
The pH of a solution is given by the formula:
\[ \text{pH} = -\log[H^+] \]
For a solution with pH 4:
\[ [H^+] = 10^{-4} \, \text{M} \]

### Step 2: Determine the concentration of OH⁻ ions in the solution with pH 10.
Using the relationship between pH and pOH:
\[ \text{pH} + \text{pOH} = 14 \]
For a solution with pH 10:
\[ \text{pOH} = 14 - 10 = 4 \]
Now, calculate the concentration of OH⁻ ions:
\[ [OH^-] = 10^{-4} \, \text{M} \]

### Step 3: Analyze the neutralization reaction.
When we mix equal volumes of the two solutions, the H⁺ ions from the acidic solution (pH 4) will react with the OH⁻ ions from the basic solution (pH 10):
\[ H^+ + OH^- \rightarrow H_2O \]

Since both the concentrations of H⁺ and OH⁻ are equal at \( 10^{-4} \, \text{M} \), they will completely neutralize each other.

### Step 4: Determine the resulting pH.
After neutralization, the resulting solution will be neutral. The pH of a neutral solution at 25°C is 7. Therefore, the pH of the resulting solution after mixing the two solutions will be:
\[ \text{pH} = 7 \]

### Final Answer:
The pH of the resulting solution is **7**.

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