Heat Energy and Physical Changes
Given: For H2O:
Hfus = 6.02 kJ/mol,
Hvap= 40.7 kJ/mol,
cice= 2.03 J/(g*°C),
csteam= 2.0 J/(g*°C)
1. Determine the number of calories in 36.89J of energy.
2. A glass of 347g of water at 25.0°C is cooled to 13.2°C. Determine the heat exchanged by the water. Is this heat
gained or lost by the water?
3. If 877J of heat is transferred to 347g of water at 13.2°C, what will the water’s new temperature be?
4. Calculate the energy required to melt 15.5g of ice (the ice is at 0°C).
5. Calculate the energy released when 31.252g of water freezes (the water is at 0°C).
6. Calculate the energy required to melt 12.5g of ice at 0°C and then raise the temperature of the water to 25°C.
Hint: This is a 2-part process.
7. Calculate the energy required when to turn 12.5g of ice at -20.0°C to water at 0°C. Hint: This is a 2-part process.
8. Calculate the energy required to vaporize 15.5g of water (the water is at 100°C).
9. Calculate the energy released when 31.252g of steam condenses (the water is at 100°C).
10. How much heat would it take to raise 43.0g of H2O at -15.0°C to 25.0°C. (Hint: This is a 3-part problem!) Draw
the graph first and then solve!
10. How much heat would it take to raise 43.0g of H2O at 75.0°C to 125.0°C. (Hint: This is a 3-part problem!) Draw
the graph first and then solve!