Heat Capacity Answers
1. What are the units for specific heat capacity?
Joules Per Kelvin
2. Iron has a specific heat capacity of 460 J/kg/°C. How much energy would be needed to increase the temperature of 1 kg iron by 1°C?
mass x heat capacity x (start temperature - finish temperature)
1 x 460 x 1
= 460 J
3. How hot does a 3.5 kg brick get if it’s heated from 20°C by 20,000 J (20 kJ)?
26.8°C
4. What happens to the molecules in a liquid as it gets hotter?
As the temperature of the liquid increases, the molecules will begin to speed up
5. What happens to the molecules in a solid as it gets hotter?
As the temperature of the liquid increases, the molecules will begin to vibrate faster
6. How much energy will it take to raise 3 kg of water by 5°C? (water has a specific heat capacity of 4,200 J/kg°C)
mass x heat capacity x (start temperature - finish temperature)
3 x 4,200 x 5
63,000 J
7. How much energy will a 30 W heater provide in 5 minutes?
9,000 J
8. How much thermal energy does a 2 kg steel block (c = 450 J/kg°C) lose when it cools from 300°C to 20°C?
mass x heat capacity x (start temperature - finish temperature)
2 x 450 x (300 - 20)
= 252,000 J
9. The specific heat capacity of copper is 390 J/kg/°C. How much energy would it take to raise the temperature of 3.5 kg copper by 12°C?
mass x heat capacity x (start temperature - finish temperature)
3.5 x 390 x 12
= 16,380 J
10. The specific heat capacity of copper is 390 J/kg/°C. How much energy would it take to raise the temperature of 42 kg copper by 71°C?
mass x heat capacity x (start temperature - finish temperature)
42 x 390 x 71
1,162,980