Heat: Calculating Calories, Conservation
of Matter and Equilibrium
Investigation 5 “Energy Transfer”
Chemical Interactions
Grade 8
Calorie

Temperature is measured in degrees Celsius
(*C).

Heat is not measured in degrees Celsius.

Heat is measured in calories (cal).

The calorie is the unit of heat in the metric system.
Calculating Heat

The amount of heat needed to
change the temperature if a
mass of water is measured in
calories.
Calorie Equation

The equation for calculating the amount
of heat needed to heat up or cool down
a mass of water is…
cal = m x

T
Calorie Equation Continued

The number of calories needed to
change the temperature of a mass
of water is equal to the mass of
water (in grams) times the
temperature change (in degrees
Celsius).
 Water: 1mL = 1 g = 1*Celsius
Conservation of Energy

The amount of energy in a
system is always the same no energy is ever created,
and no energy is
destroyed.
Energy Transfer

Energy can transfer from one place to
another.

Energy can be transformed from one
kind of energy into another kind of
energy.

i.e. Mixing hot and cold water = warm
water
Equilibrium

Every time a particle with high kinetic
energy from the hot water hit a particle
with low kinetic energy from the cold
water, the kinetic energy of both
particles changed:

The hot water particle slowed down and
the cold water particle sped up.
Final average speed

The final average speed of the particles
was faster than the particles in the the
original cold water, and slower than the
original hot water.
Equilibrium

Energy transfer continues as particles
continue to bang into one another.


But the number of particles graining energy
will be the same as the number of particles
loosing energy.
The temperature will hold steady.
Equilibrium

When a system is in balance,
and there is no net energy
transfer going on, the system is
in equilibrium.

When mixing hot and cold water, the
final temperature was its equilibrium
temperature.
Energy Transfer Vocabulary

Calorie (cal): A unit of heat; the amount
of heat needed to raise the temperature
of 1 g (gram) of water to 1*(*degree)C.

Conduction: The transfer of energy as a
result of contact between particles.
Energy Transfer Vocabulary

Energy Transfer: The movement of
energy from a location with more energy
to a location with less energy.

Equilibrium: The condition of a system
when no observable change is taking
place.
Energy Transfer Vocabulary

Energy Transfer: The movement of
energy from a location with more energy
to a location with less energy.

Equilibrium: The condition of a system
when no observable change is taking
place.
Energy Transfer Vocabulary

Heat: A form of energy related to the
kinetic energy of particles.

Kinetic Energy: The energy due to
motion. The kinetic energy of particles is
heat.
Energy Transfer Vocabulary

Temperature: A measure of the average
kinetic energy of the particles of a
substance.
FOSS Web

FOSS Web Multimedia:

Mixing Hot and Cold Water
Energy Flow

http://www.fossweb.com/
