How to Calculate Gas Collection
What is Gas Collection?
Gas collection by water displacement; measured gas volume must be corrected for water vapor pressure at temperature.
Step-by-Step Guide
- 1Input measured volume, temperature, atmospheric pressure
- 2Correct for water vapor pressure
- 3Calculate dry gas volume at STP or other condition
Worked Examples
Input
O₂ collected at 25°C, 760 mmHg, wet
Result
Correct for 23.8 mmHg H₂O vapor pressure; V_dry = 0.969 × V_wet
Common Mistakes to Avoid
- ✕Forgetting water vapor pressure correction
- ✕Not converting to STP correctly
Frequently Asked Questions
Why correct for water vapor?
Measured gas is mixture of gas + H₂O vapor; must subtract partial pressure for true gas amount.
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