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Checking Pressure After Water Condenses 4 questions
Checking Pressure After Water Condenses
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A rigid classroom chamber contains dry air and water vapor. No material enters or leaves. The dry air does not condense. The pressure contributions of dry air and water vapor add, and at fixed volume the pressure of an unchanged amount of either gas is proportional to its Kelvin temperature. The model allows water vapor to condense, but it cannot be taken up by any other process.
| Record | Temperature (K) | Dry-air pressure (kPa) | Water-vapor pressure (kPa) |
|---|---|---|---|
| Before cooling | 320 | 96 | 8.0 |
| After cooling | 300 | Hidden | 3.5 |
Question 1
What dry-air pressure does the model predict after cooling?
- 90 kPa
- 93.5 kPa
- 96 kPa
- 104 kPa
Question 2
Use the predicted dry-air pressure and the measured water-vapor pressure to find the final total pressure. Show the sum.
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Question 3
A student attributes the entire water-vapor pressure decrease to the lower temperature, with no condensation. Use a predicted pressure to evaluate the claim.
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The chamber warms back to 320 K. The model reports that all condensed water evaporates again and no material is lost.
Question 4
Predict the total pressure after the return to 320 K and explain why both contributions return to their original values.
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