Download Heating Curves

Heating Curves
Phase Changes
• A heating curve graphically represents the phase
transitions that a substance undergoes as heat is added
to it.
• The plateaus on the curve mark the phase changes.
• The temperature remains constant during these phase
transitions.
Thermal Energy =
PE + KE
PE or KE?
• When the phase (liquid,
solid or gas) does not
change, the heat being
absorbed is accounted
for as KE and T changes
• When the phase
changes, the heat is
accounted for as PE and
T does not change
Specific Heat Capacity
• Different materials respond differently to
energy (heat) inputs.
• Specific Heat Capacity is a way to measure
mathematically how materials respond to
heat.
Formula for Specific Heat
• Q=cm∆T
– Q=heat added (Joules)
– C =specific heat capacity (Joules/kg*°C)
– M=mass of object (kg)
– ∆T = change in temperature (°C)
<<<<<OR>>>>>
Joules = Joules x (kg) x (°C)
(kg)(°C)
An Example
• Find the change in thermal energy of a 10 kg
container of water that warms from 10°C to
30°C . The specific heat capacity of water is
4184 J/kg°C.
LESS
L = List
•
•
•
•
Q=?
C = 4184 J/kg°C
M = 10 kg
∆T = 30°C -10°C = 20°C
LESS
E = Equation
• Q=cm∆T
LESS
S = Substitution
• Q=cm∆T
Q = (4184)(10)(20)
LESS
S = Solve
Q = (4184)(10)(20)
Q = 836,800 Joules
You try…
Find the change in thermal energy of 20 kg
wooden chair that warms from 5°C to 28°C if the
specific heat capacity of wood is 1,700 J/(kg°C).
You try…
Find the specific heat capacity of an unknown
object if the thermal energy added is 350,000 J
and the mass of the object is 10 kg and the
temperature change is 8.37°C.
Beyond the bend…
• The earth’s surface is 70% water. Why is our
discussion of specific heat capacity important
as it relates to climate change?