H12_4-12-10

# H12_4-12-10 - You may use other materials in the room such...

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H12: Rate of cooling, conservation of energy, Emmy Noether Materials: two small Styrofoam cups, each containing 200 mL of hot water, temperature probes Initial Instructions and questions: Design an experiment to test your ability to maintain the temperature of a sample of hot water or to make it cool rapidly. You will start with two small Styrofoam cups, each containing 200 mL of hot water, with one temperature probe in each. Set up your experiment to take data for 30 minutes. Start your experiment when both probes have come to equilibrium with the hot water. Your goal is to keep the water hot in one cup and to cool the water in the other cup as quickly as possible. The experiment is over when the temperatures in the two cups differ by at least 30 °C. The shortest time wins.
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Unformatted text preview: You may use other materials in the room such as hot water, cold water, cups, pieces of Styrofoam but nothing but the probe may be put into either of the small cups. The hotplates or other heaters may not be used. Guide to notes in your lab notebook: 1. What were the final temperatures of the water in the two cups? How long did it take to reach the 30 °C difference? 2. What method did you use to speed up and slow down the cooling? 3. What would you change in order to reduce your time? Practice problems: 1. 100 g of Liquid 1 (c 1 = 0.60 cal/g•°C) at 80 °C is mixed with 100 g of Liquid 2 (c 2 = 0.80 cal/g•°C) at 40 °C. What is the final temperature of the mixture? 2. How much heat is required to change 20 g of ice at -10 °C into 20 g of steam at +110 °C?...
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