How many liters of dry hydrogen gas, measured at 796 torr and 25°C, will be released by the decomposition of 255 milliliters of H₂O(g) at 1.33 atm and 25°C?

A. 0.325 L
B. 0.255 L
C. 0.139 L



Answer :

Sure! Let's solve this step-by-step using the principles of ideal gas law and conversion between units.

### Given values:
- Initial Pressure (P₁): 1.33 atm
- Initial Volume (V₁): 0.255 liters (255 milliliters converted to liters)
- Initial Temperature (T₁): 25°C (which needs to be converted to Kelvin, T = 25 + 273.15 = 298.15 K)
- Final Pressure (P₆): 796 torr (which needs to be converted to atm, 796/760 ≈ 1.0474 atm)
- Final Temperature (T₂): 25°C (also 298.15 K, because temperature remains the same)

### Step-by-Step Solution:

1. Convert all given units to the proper units used in gas law calculations (Pressure in atm, Volume in liters, Temperature in Kelvin).
- Initial Pressure (P₁): Already in atm (1.33 atm)
- Initial Volume (V₁): Already in liters (0.255 L)
- Initial Temperature (T₁): 25°C converted to Kelvin (298.15 K)
- Final Pressure (P₂): 796 torr converted to atm (796/760 ≈ 1.0474 atm)
- Final Temperature (T₂): 25°C converted to Kelvin (298.15 K)

2. Use the Ideal Gas Law relation for two sets of conditions:
[tex]\[ \frac{P₁ \cdot V₁}{T₁} = \frac{P₂ \cdot V₂}{T₂} \][/tex]

3. Rearrange the equation to solve for V₂ (final volume):
[tex]\[ V₂ = \frac{P₁ \cdot V₁ \cdot T₂}{P₂ \cdot T₁} \][/tex]

4. Substitute in the known values:
[tex]\[ V₂ = \frac{1.33 \cdot 0.255 \cdot 298.15}{1.0474 \cdot 298.15} \][/tex]

(Since T₁ = T₂, the temperature values will cancel out in the division.)

5. Simplify the equation:
[tex]\[ V₂ = \frac{1.33 \cdot 0.255}{1.0474} \][/tex]

6. Calculate the result:
[tex]\[ V₂ ≈ \frac{0.33915}{1.0474} \approx 0.3238 \text{ liters} \][/tex]

### Conclusion:
The volume of dry hydrogen gas released would be approximately 0.324 liters. Therefore, the closest answer from the options provided:

0.325 L

This result matches the solution and confirms our step-by-step calculations.