Cracking the SAT Physics Subject Test

Notice how little the temperature of the water changed. Water has a very high
specific heat and can absorb large amounts of thermal energy without undergoing
much of a temperature change. We could have used this same experiment to
determine the specific heat of Teflon. Drop a known mass of Teflon at a given
temperature into the water and then measure the temperature of the water once
thermal equilibrium is reached. Knowing this final temperature, we could solve for
cTeflon.

Calorimetry II: Heat Transfer and Phase Changes

Remember that when an object absorbs or loses heat, either its temperature will
change or the phase of the object will start to change, but not both. For example, if
we start heating an ice cube that’s at 0°C, the heat causes the ice cube to melt, but
the temperature remains at 0°C throughout the melting process. Only when the ice
cube has completely melted will any additional heat cause the temperature to rise.

The equation that applies during the melting of the ice cube (or during any

other phase transition) is the following:

Q = mL

where L is the latent heat of transformation.

This equation tells us how much heat must be transferred to cause a sample of mass
m to completely undergo a phase change. In the case of a solid-to-liquid (or vice
versa) phase change, L is called the latent heat of fusion. For a phase change
between liquid and vapor, L is called the latent heat of vaporization.

Plasma

For the sake of being

comprehensive, know that

there’s a fourth state of

matter called plasma. That

said, it won’t be covered

on the SAT Physics exam.