Thermodynamics
Introduction
Thermodynamics
Heat
Changes
I am hot vs. I am cold
Measure of the same thing!!!
HEAT . VS. TEMPERATURE
 form of energy  measurement of heat energy
 depends on amount of matter  doesn’t depend on amt. of matter
 total  average
Calorimeter
Measures energy changes
 Joules (J): metric unit of heat E
 H2O: 1g  raise 1°C
How much heat is needed?
4.18J = 1 cal
25°C
26°C
• Aluminum: 1 g  raise 1°C  0.903J
SPECIFIC HEAT CAPACITY (c)
• the amount of heat needed to raise the
temperature of 1g of a substance by 1°C.
J
cwater  4.18J
g C
g C
Heat Calculations
 Law of Conservation of Energy
heat lost = heat gained
 Heat flows from warmer to cooler areas.
E = m ∙ T ∙ c
Change in energy:
heat lost or gained
Specific heat
capacity
Mass (g) of substance Change in temperature:
Tf - Ti
Ex 1: How much heat is lost when an aluminum block
with mass of 4110g cools from 660.0°C to 25.0°C?
m
cAl=0.903 J g C
E = (4110g)(25 - 660°C)(0.903 J g C )
= - 2.36 x 106 J
lost 2360000 J
Ti
Tf
m
Ex 2: If a sample with a mass of 23.10g changes
temperature from 35.0°C to 50.0°C by absorbing
457.0J of energy, what is the specific heat?
E
Ti
E = m ∙ T ∙ c
457.0 J   23.10g  50.0  35.0C  c 
457.0 J
c
 23.10 g  50.0  35.0C 
c  1.32J
g C
Tf