Question

You have a 50.0-g sample of water at 20C. To it, you add a 50g sample of water at 80C. The final temperature of the water should be

A. Between 50C and 80C
B. Above 80C
C. Between 20C and 50C
D. 50C

Answer 1

The final temperature of a mixture of equal masses of water at 20°C and 80°C will be 50°C, which is the weighted average of the two initial temperatures.

Step-by-step explanation:

When mixing two samples of water at different temperatures, the final temperature of the mixture will be a weighted average of the two initial temperatures, assuming no heat loss to the environment. In the case of a 50.0-g sample of water at 20°C mixed with a 50g sample of water at 80°C, the final temperature would be exactly in the middle of the two starting temperatures, because the masses of the two water samples are equal and water has a specific heat capacity that would not change based on temperature within this range. Therefore, the final temperature of the mixture should be D. 50°C.