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Reading a Crystallization Temperature Spike 4 questions

Reading a Crystallization Temperature Spike

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A class models two liquid samples cooling in the same cabinet. Neither has a heater. At minute 4 each sample receives a small crystal seed. Treat the seeds as too small to change the temperatures directly. Crystals then grow in A but do not grow in B.

At 0, 2, 4, 6, 8, 10, and 12 minutes, A is at 32, 28, 25, 31, 28, 26, and 24 °C. B is at 32, 28, 25, 23, 21, 20, and 19 °C.
Temperature readings for samples A and B.
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Question 1

Which observation distinguishes A from B just after minute 4?

  1. A warms while B continues to cool.
  2. Both samples warm by the same amount.
  3. A cools while B warms.
  4. Both samples stay at 25 °C.

Question 2

Explain how the growing crystals can account for A warming without a heater.

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In a simple energy model, the warming of A requires 10 J of thermal energy per degree Celsius. From minute 4 to minute 6 another 20 J leaves A for the cabinet.

Question 3

Estimate the total energy released by crystallization in A during that interval. Include the thermal energy gain and the transfer to the cabinet.

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Question 4

A student estimates the energy release from the temperature rise alone. Explain why that estimate is smaller than the total in this model.

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