Questions on Heat for J2 and J3

Heat Problems

1. Calculate the heat energy required to heat 200.0 g of water for soup from 10 degree C to boiling point.

2. What amount of heat is needed to heat 50.0 kg of water in a dishwasher from 10 degree C to 70 degree C?

3. You have 2.50 kg of mercury at 22 degree C. You find that it requires 3.20 x 103 J of energy to raise its temperature to 32 degree C. Calculate the specific heat capacity of mercury.

4. To raise the temperature of 400.0 g of gold from 50 degree C to 75 degree C, 1.3 kJ of energy is needed. What is the specific heat capacity of gold?

5. A piece of metal with a mass of 500.0g is put into boiling water until it is the same temperature as the boiling water. It is then transferred very quickly into 200.0g of water, which is 20 degree C. The final temperature of the water and metal is 30 degree C.
a) How many joules of energy did the 200.0 g of water absorb as it was heated?
b) How many joules of energy did the metal release as it cooled?
c) What is the specific heat of the metal?

6. To cool 400. g of a solid having an initial temperature of 85 degree C, you put it into 200.g of water at 15 degree C. If the final temperature of the solid and water is 35 degree C, determine the specific heat capacity of the unknown substance.

7. 3.00 x 104 J of heat energy is added to a 1.00 kg block of aluminum that has an initial temperature of 10 degree C. The specific heat for aluminum is 9.20 x 102 J/kg°C. Calculate the final temperature.

8. An unknown piece of metal that has 0.200 kg mass is heated to 350 degree C. It is quickly placed in 0.250 kg of water at 20 degree C, which is contained in a 225 g aluminum calorimeter. The final temperature of the metal, water, and calorimeter is 38 degree C. What is the specific heat capacity of the unknown metal?

9. A 10.0 kg piece of brass at 71 degree C is placed in 20.0 kg of water that is 10 degree C. What is the final temperature of the brass and water?

Latent Heat Problems
1. Which takes more heat, melting ice or evaporating water?

2. Explain why ice is useful in coolers.

3. How much heat is given off when 3.2 kg of water freeze? Assume the temperature stays constant at 0ºC.

4. How much heat is required to change 2.5 kg of water at 20ºC to steam at 150ºC?

5. How much heat is needed to change 2.0 kg of silver at 20ºC into liquid silver? Silver melts at 961ºC.

6. How much heat is needed to change 0.50kg of ice at –20ºC into steam at 120ºC?

7. How much heat is released when 500g of steam at 250ºC is cooled to ice at –40ºC?