UNIT THREE: Matter, Energy, and
Earth
 Chapter 8 Matter and Temperature
 Chapter 9 Heat
 Chapter 10 Properties of Matter
 Chapter 11 Earth’s Atmosphere and
Weather
Chapter Nine: Heat
 9.1 Heat
 9.2 Heat Transfer
Chapter 9.1 Learning Goals
 Describe the relationship between heat,
temperature, and thermal energy.
 Identify and use different units to measure
heat.
 Explain how the specific heat of different
materials can be used to describe changes in
temperature and energy.
Investigation 9A
Temperature and Heat
 Key Question:
How are temperature and heat related?
9.1 What is heat?
 Heat is thermal energy that is
moving.
 Heat flows any time there is a
difference in temperature.
 Because your hand has more
thermal energy than chocolate,
thermal energy flows from your
hand to the chocolate and the
chocolate begins to melt.
9.1 What is heat?
 Heat and temperature are
related, but are not the
same thing.
 The amount of thermal
energy depends on the
temperature but it also
depends on the amount
of matter you have.
9.1 Units of heat and
thermal energy
 The metric unit for
measuring heat is
the joule.
 This is the same
joule used to
measure all forms
of energy, not just
heat.
9.1 Heat and thermal energy
 Thermal energy is often measured in calories.
 One calorie is the amount of energy it takes to
raise the temperature of one milliliter of water by
one degree Celsius.
9.1 Specific heat
 The specific heat is a
property of a
substance that tells
us how much heat is
needed to raise the
temperature of one
kilogram of a material
by one degree
Celsius.
Knowing the specific heat of a material tells you how
quickly the temperature will change as it gains or loses
energy.
9.1 Why is specific heat different for
different materials?
 Temperature measures the average kinetic
energy per particle.
 Energy that is divided between fewer particles
means more energy per particle, and therefore
more temperature change.
 In general, materials made up of heavy atoms or
molecules have low specific heat compared with
materials made up of lighter ones.
Solving Problems
How much heat is needed to raise the
temperature of a 250-liter hot tub from
20°C to 40°C?
Solving Problems
1. Looking for:

…amount of heat in joules
2. Given:



V = 250 L, 1 L of water = 1 kg
Temp changes from 20°C to 40°C
Table specific heat water = 4, 184 J/kg°C
3. Relationships:

E = mCp(T2 – T1)
4. Solution:

E = (250L × 1kg/L) × 4,184 J/kg°C (40°C - 20°C) =
20,920,000
Sig.
fig./Sci.J not. 20,920,000 J = 2.1 x 107 J
Investigation 9C
Specific Heat of a Metal
 Key Question:
How can you use specific
heat to identify an unknown
metal sample??