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Tracking a Hidden Water Layer in a Cup 4 questions
Tracking a Hidden Water Layer in a Cup
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A museum cup model holds two sealed water compartments separated by a thin wall. Water cannot cross the wall, but heat can. The outer compartment contains 100 g of water at 20 °C. A warm inner compartment contains 100 g of water at 40 °C. No energy goes to the surroundings, and the two water portions have the same specific heat. The walls and cup store negligible energy.
Question 1
Which process can happen through the separating wall?
- Heat transfers from the inner water to the outer water.
- Heat transfers from the outer water to the inner water until both reach 20 °C.
- Water moves from the inner compartment into the outer compartment.
- Both portions lose thermal energy at the same time.
Question 2
Predict the common final temperature if the cup contains only the two compartments described. Use the equal water masses in your reasoning.
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The display adds a sealed pocket of 100 g of water at 20 °C behind the outer compartment. All three portions can exchange heat. The water masses, starting temperatures, and negligible losses for the original two portions are unchanged.
Question 3
Calculate the common final temperature in the three-compartment model. Show how the hidden water changes the energy balance.
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Question 4
A student sees the lower final temperature and concludes that heat escaped from the cup. Explain how the hidden pocket offers another explanation.
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