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Energy – the ability to do work or produce
heat
◦ Kinetic energy – energy of motion
◦ Potential energy – stored energy
 Chemical potential energy – stored energy because of
composition
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Heat – energy process of flowing from a
warmer object to a cooler object
◦ Calorie – the amount of heat required to raise the
temperature one degree Celsius
◦ Joule – SI unit of heat and energy

When your body breaks down sugars and fats
to form carbon dioxide and water, these
exothermic reactions generate heat that can
be measured in Calories
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Specific heat – amount of heat required to
raise the temperature of one gram of that
substance by one degree Celsius
Units - J/g ⁰ C
Large specific heats = Large amount of
energy to change temperature (water)
Small specific heats = Small amounts of
energy to change temperature (gold)
q = m x c x ∆T
q = mc∆T
q (heat)
c (specific heat)
m (mass of sample)
∆T (change in temperature)
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The temperature of a sample of iron with a mass of 10.0g
changed from 50.4⁰C to 25.0 ⁰ C with the release of 114J heat.
What is the specific heat of iron?
q = mc∆T
Heat (q)
◦ 114J

Mass (m)
◦ 10.0g

Specific Heat (c)
◦ X

Change in temperature (∆T)
◦ 50.4⁰C - 25.0 ⁰ C = 25.4 ⁰ C
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114 = 10.0(x)25.4
114 = 254(x)
X=.44881
Final answer 0.449J/g ⁰ C (3 significant figures and units)

Calorimeter – insulated device used for
measuring the amount of heat absorbed or
released during a chemical or physical
process

Thermochemistry is the study of heat
changes that accompany chemical reactions
and phase changes

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Enthalpy (H) is the heat content of a system at
constant pressure
Enthalpy of reaction
◦ ∆Hrxn=Hproducts – Hreactants

Endothermic = absorbs heat giving the ∆Hrxn a positive number

Exothermic = releases heat giving the ∆Hrxn a negative number