1 cc of 0:1 N HCI is added to 999 cc solution of NaCl. The pH of the resulting solution will be

Options

A. 7
B. 4
C. 2
D. 1

Answer

To find the pH of the resulting solution when 1 cc of 0.1 N HCl is added to 999 cc of NaCl solution, we can follow these steps:

### Step 1: Calculate the moles of HCl added
Given:
- Volume of HCl = 1 cc = 0.001 L
- Normality of HCl = 0.1 N

Moles of HCl = Normality × Volume (in L)
\[ \text{Moles of HCl} = 0.1 \, \text{N} \times 0.001 \, \text{L} = 0.0001 \, \text{moles} \]

**Hint:** Remember that normality is equivalent to molarity for strong acids like HCl since they completely dissociate.

### Step 2: Calculate the total volume of the solution
The total volume after adding HCl to NaCl solution:
\[ \text{Total Volume} = 999 \, \text{cc} + 1 \, \text{cc} = 1000 \, \text{cc} = 1 \, \text{L} \]

**Hint:** Always convert volumes to the same unit (liters) when performing calculations.

### Step 3: Calculate the concentration of HCl in the final solution
Concentration of HCl in the total solution:
\[ \text{Concentration of HCl} = \frac{\text{Moles of HCl}}{\text{Total Volume in L}} = \frac{0.0001 \, \text{moles}}{1 \, \text{L}} = 0.0001 \, \text{M} \]

**Hint:** Concentration is calculated by dividing the number of moles by the volume of the solution in liters.

### Step 4: Calculate the pH of the solution
Since HCl is a strong acid, it completely dissociates in solution:
\[ \text{[H}^+\text{]} = 0.0001 \, \text{M} \]
Now, we can calculate the pH:
\[ \text{pH} = -\log[\text{H}^+] = -\log(0.0001) = 4 \]

**Hint:** The pH scale is logarithmic, and the formula for calculating pH is based on the concentration of hydrogen ions in the solution.

### Final Answer:
The pH of the resulting solution will be **4**.