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/