A mixture of helium of neon gases is collected over water at `28.0^(@)C` and 745 mmHg. If the partial pressure of helium is 368 mmHg, what is the partial pressure of neon?

Options

A. 348.7 mmHg
B. 377 mmHg
C. 384.7 mmHg
D. none of these

Explanation

To find the partial pressure of neon in a mixture of helium and neon gases collected over water, we can use Dalton's Law of Partial Pressures, which states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each individual gas in the mixture, including the vapor pressure of water.

### Step-by-Step Solution:

1. **Identify the Given Values**:
- Total pressure (P_total) = 745 mmHg
- Partial pressure of helium (P_He) = 368 mmHg
- Vapor pressure of water at 28.0°C (P_H2O) = 28.3 mmHg (this value is typically looked up in a table)

2. **Apply Dalton's Law of Partial Pressures**:
According to Dalton's Law:
\[ P_{total} = P_{He} + P_{Ne} + P_{H2O} \]
Rearranging the equation to find the partial pressure of neon (P_Ne):
\[ P_{Ne} = P_{total} - P_{He} - P_{H2O} \]

3. **Substitute the Values**:
Substitute the known values into the equation:
\[ P_{Ne} = 745 \, \text{mmHg} - 368 \, \text{mmHg} - 28.3 \, \text{mmHg} \]

4. **Perform the Calculation**:
\[ P_{Ne} = 745 - 368 - 28.3 = 348.7 \, \text{mmHg} \]

5. **Final Result**:
The partial pressure of neon is:
\[ P_{Ne} = 348.7 \, \text{mmHg} \]