## Heat Capacity Answers

## 1. What are the units for specific heat capacity?

## Joules Per Kelvin

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## 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

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## 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

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## 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

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