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Checking Where Bubbles Come From in Water 4 questions
Checking Where Bubbles Come From in Water
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A classroom model warms equal amounts of water at 1 atm. Sample P contains dissolved air. Sample Q has very little dissolved air. Both start at the same temperature. In the model, warming can release dissolved air while the water remains below its boiling temperature.
| Observation | Sample P | Sample Q |
|---|---|---|
| Wall bubbles at 60 °C | Many | Few |
| Sustained bubbling at 100 °C | Yes | Yes |
| Temperature during sustained bubbling | 100 °C | 100 °C |
Question 1
Which comparison supports the idea that some early bubbles come from dissolved air?
- The samples start at the same temperature.
- At 60 °C P shows many wall bubbles while Q shows few.
- Both samples show sustained bubbles at 100 °C.
- Both temperatures remain at 100 °C during sustained bubbling.
Question 2
Compare the 60 °C and 100 °C observations. Explain how the amount of dissolved air changes the early record while both samples show the same evidence of boiling later.
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The model collects some gas from each stage and cools it. Water vapor can condense in the collector. The gases in air remain gases there.
Question 3
What observation in the collector would show that water vapor was present? Explain.
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Question 4
A student says water molecules must split before entering a boiling bubble. Evaluate the claim using a particle model of boiling.
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