1. A block of lead at 100°C is put into an equal mass of cold water at 0°C in an insulated container. The system is allowed to come to equilibrium.
a) Which has greater magnitude, the heat energy transferred out of the lead, or the heat energy transferred into the water? Explain your reasoning.
b) Which undergoes a temperature change of greater magnitude, the lead or the water? Explain your reasoning.
c) Is the final equilibrium temperature greater than, less than or equal to 50°C? Explain.
2. Suppose you heated 1 kg of each of the substances listed below until they were at their melting temperature, and then continued to heat substance at a constant rate. Rank the order of the substances from the shortest (1) to the longest time to melt (6). Use table 17.3, page 564, in your textbook to help you answer this question.
____ aluminum ____ iron ____ silver____ copper ____ lead ____ water Explain your reasoning.
3. When you put water at 25°C into an ice tray and freeze it in a refrigerator, is more heat energy transferred in bringing the water to the freezing temperature or during the process of freezing? Or are equal amounts of heat transferred? Explain your reasoning.
during the process of freezing
4. When you stir the hot coffee in a cup, the energy you input with the spoon
a) moves the cup back and forth.
b) cancels out if you stir both back and forth.
c) cools the coffee by decreasing the kinetic energy of its molecules.
d) increases the kinetic energy of the molecules of the coffee.
e) You can't input energy to coffee by stirring it.
Explain your choice.
5. A cook put two large saucepans of potatoes on a gas stove to boil. When they were both boiling, she turned the gas under one down to low so that the water was just kept boiling. She left the other on high. Which will cook more quickly, the potatoes on high, the potatoes on low, or will they cook at the same rate? Explain your reasoning.