7.3 Heat
pp. 176 - 180
Mr. Richter
Agenda
 Warm-Up
 Introduction to Heat
 Check and Review HW
 Notes:
 Business:
 Collect/Return Lab
Notebooks
 Thermal Energy
 Specific Heat Capacity
 Calculating with Specific
Heat Capacity
 Anyone who still owes me a
quiz is taking it today after  Lab Postponed Until
school!
Tomorrow
Objectives: We Will Be Able To…
 Explain the difference between temperature and thermal
energy.
 Define heat.
 Calculate the heat required to raise the temperature of a
material.
Warm-Up:
 Which do you think would be harder to melt: a 1 kg block of
ice or a 1 kg block of iron? Why?
 Discuss at your table. Then write a 1-2 sentence explanation
in your notebook.
Thermal Energy
What is heat?
Thermal Energy
 Any object that has some temperature above absolute zero
has some thermal energy, or energy due to its temperature.
 The little vibrations of the atoms of that object have the ability
to cause change.
 The thermal energy of a hot stove can turn water into steam.
 The thermal energy of the oceans can warm or cool an entire
planet.
Thermal Energy
 Thermal energy is the SUM of all of the
random kinetic energies of the atoms or
molecules of a substance.
 Add up all of the kinetic energies of each
individual atom.
 Temperature is the AVERAGE of the random
kinetic energies.
 Do substances with the same temperature
necessarily have the same thermal energy?
 No! It depends on how much of each
substances there is. More mass means more
thermal energy!
Thermal Energy
 What do we mean when we say “heat”?
 When we say heat, we’re usually talking about
something that
 “feels warm”
 “is hotter” than something else
 We’re actually describing when thermal energy is
flowing from one object to another. Heat flows
naturally from hot objects (higher energy) to
colder objects (lower energy).
 Heat is just describing the transfer of thermal
energy.
Specific Heat Capacity
Specific Heat Capacity
 Does it take the same amount of energy to heat up a block of
is as it does to heat up a block of iron?
 Of course not! Every material has a different molecular
structure.
 This means that each material requires different amounts of
energy to get its molecules or atoms to vibrate faster.
Specific Heat Capacity
 Specific heat capacity is a measure of how much energy is
required to raise the temperature of a substance.
 Specifically (get it?), specific heat capacity is a measure of
how much energy is required to raise the temperature of 1
kg of a substance by 1 °C.
 For example:
J
 the specific heat capacity (C) of water is 4,184 kg oC
 it takes 4,184 J to raise the temperature of 1 kg of water by 1°C.
 this is approximately equivalent to 1 Calorie
Specific Heat Capacity
 Some different specific heat capacities:
 Which material requires more energy
to raise its temperature by 10 °C: oil or
silver?
 Oil: its specific heat capacity is higher,
so it requires more thermal energy to
raise its temperature.
Calculating with Specific Heat
Capacity
Calculating with Specific Heat Capacity
 The amount of energy required to change the temperature of
an object depends on three things:
 the specific heat capacity of the object (what material is it?)
 the mass (how much?)
 the change in temperature
Q = mcΔT
Your Book
MCAS
Calculating with Specific Heat Capacity
 Use the chart on page 179.
1. How much energy is required to raise the temperature of 30
kg of steel from 15 °C to 30 °C?
2. How much energy is required to raise the temperature of
100 kg of water by 40 °C?
Wrap-Up: Did we meet our objectives?
 Explain the difference between temperature and thermal
energy.
 Define heat.
 Calculate the heat required to raise the temperature of a
material.
Homework
 Due Thursday
 p. 179 #a, b
 p. 180 # 1-3