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Checking Boiling With Two Heater Settings 4 questions
Checking Boiling With Two Heater Settings
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A classroom model heats equal amounts of pure water from the same starting temperature. The chamber fixes the pressure above each sample. A sustained plateau during boiling gives the temperature at which the water vapor pressure matches the chamber pressure. The table gives rounded model temperatures.
| Test | Chamber pressure (kPa) | Heater power (W) | Time when boiling starts (min) | Boiling plateau (°C) |
|---|---|---|---|---|
| P | 80 | 20 | 8 | 94 |
| Q | 80 | 40 | 4 | 94 |
| R | 100 | 40 | 5 | 100 |
Question 1
Which pair isolates the effect of heater power at the same chamber pressure?
- P and Q
- P and R
- Q and R
- No pair uses the same pressure.
Question 2
Use P and Q to evaluate the claim that increasing heater power raises the boiling temperature at fixed pressure.
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The class prepares a fourth sample at 100 kPa with a 20 W heater. The water and its starting temperature match the other samples.
Question 3
Predict the fourth sample’s plateau temperature. Explain whether P or R supplies the more relevant comparison for that prediction.
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Question 4
Explain how the fourth sample and R can be used to check whether heater power changes the time to reach the same plateau.
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