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Energy
· We are all familiar with energy labels on food
· We measure energy in joules, however when
we refer to food we talk about Calories
· 1 calorie = 4.2 joules
· How do we release the energy in food?
· Is it exothermic or endothermic?…read more

Slide 3

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Calorimetry
· Uses the changes in the temperature of water
to measure energy released by food or
chemical reactions
· For chemical reactions the reaction is carried
out in an insulated beaker or a bomb
calorimeter (heated with electric wire)
· The energy change for the reaction can be
precisely measured…read more

Slide 4

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Specific Heat Capacity
· Is the amount of energy which is required to
raise the temperature of 1g of the substance
by 1°C
· The specific heat capacity of water is
4.2g-1°C-1…read more

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Specific Heat Capacity
· Some other common specific heat capacity's
· Magnesium 1.02g-1°C-1
· Oxygen 0.918g-1°C-1
· Paraffin Wax 2.5g-1°C-1
· Ethanol 2.44g-1°C-1
· Copper 0.385g-1°C-1
· Concrete 0.88g-1°C-1…read more

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Equation
· Energy change = mass x specific heat capacity
x change in temperature
· Question:
25cm3 of water in a test tube was heated by
burning cheesy wotsits under the tube. The
temperature of the water went up from 19°C to
54°C.
· Using the equation calculate the amount of
energy in the wotsits.…read more

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