Question

It takes 1 kcal to raise the temperature of 1 kg of liquid water by 1 C, but only 0.5 kcal to raise the temperature of 1 kg of ice or water vapor by 1 C.
Also, it takes 80 kcal to melt 1 kg of ice sitting at 0 C, and 540 kcal to evaporate 1 kg of liquid water sitting at 100 C.

1.) How much heat is required to raise the temperature of 5 kg of liquid water by 20 C?
2.) 50 kcal 100 kcal 400 kcal 2700 kcal How much heat is required to melt 5 kg of ice at 0 C?
3.) 50 kcal 100 kcal 400 kcal 2700 kcal How much heat is required to raise the temperature of 5 kg of ice by 20 C?

Answer 1

Answer:

a. 50KCal

b. 400KCal

c. Same as (a) above

Explanation:

Given

To raise the temperature of 1kg of liquid water at 1°C requires 1KCal

To raise the temperature of 1kg of ice or water vapour by 1°C requires 0.5KCal

To melt 1kg of ice at 0°C requires 80KCal

To evaporate 1kg of liquid water sitting at 100°C requires 540KCal

a. How much heat is required to raise the temperature of 5 kg of liquid water by 20 C?

To raise the temperature of 5 kg of ice by 20°C requires:

5 kg * (0.5 kcal / kgC) * 20C

= 50 KCal

b. How much heat is required to melt 5 kg of ice at 0 C?

To melt an ice of 5 kg of ice at 0 C requires:

5 kg * (80 kcal / kg)

= 400 KCal

c. Same as (a) above