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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