Question

A student heats 100 g of aluminum to 60°C. He places it in 100 g of water at 20°C. Over time, what will most likely happen?

a. The water's temperature will increase slightly, and the metal's temperature will decrease a lot.

b. The water's temperature will increase a lot, and the metal's temperature will decrease slightly.

c. The water's temperature will decrease slightly, and the metal's temperature will increase a lot.

d. The water's temperature will increase by about the same amount as the metal's temperature decreases.

Answer 1

Option A

Explanation:

Given : A student heats 100 g of aluminum to 60°C. He places it in 100 g of water at 20°C.

To find : Over time, what will most likely happen?

Solution :

We know,

Heat will flow out of the warm aluminum and into the cool water.

The final "equilibrium" temperature will be a little less than 40°C (the average of 60° and 20°), because the specific heat of the aluminum is about 8% less than the specific heat of the water.

So when some quantity of heat flows from the aluminum to the water, the temperature of the water rises a little less than the temperature of the aluminum falls.

Therefore, Option A is correct.

The water's temperature will increase slightly, and the metal's temperature will decrease a lot.

Answer 2

What is relevant here is that both water and metal have the same weight - if they had a different weight, one of them would change the temperature more than the other. (the one with more weight would change less).
But in the present case:

d. The water's temperature will increase by about the same amount as the metal's temperature decreases.