Heat vs. Temperature

Heat and temperature are two concepts that are often confused. They are related to each other because they are both related to the concept of thermal energy, As you may recall, thermal energy is the energy that a substance possesses due to the, kinetic energy, or motion of its molecules. Three factors affect the amount of thermal energy that a substance has:

1) Temperature.

Temperature is a measure of the average kinetic energy of the molecules of a substance. An increase in temperature results in an increase in the kinetic energy of the molecules and an increase in thermal energy. It is fair to say that temperature and thermal energy vary directly, but they are not the same thing.

2) Mass.

Mass is a measure of the amount of matter in a substance. It makes sense that a more massive sample will have more thermal energy than a smaller sample, if all other factors are equal. Imagine the difference in total energy between a spoonful of boiling water and a vat of boiling water.

3) Specific Heat Capacity.

Each material is able to "hold" a certain amount of thermal energy at a given temperature, due to what we call its specific heat. Think of the wide range of temperatures that your feet encounter during a day at the beach. The water may seem cold while the sand feels quite warm. The wood on the boardwalk may feel comfortable, but the blacktop in the parking lot is burning hot. Things will heat up at different rates, due, in part, to their different specific heat values.

So, as you see, temperature is one of the factors that affects the thermal energy of a substance. What is heat? Heat is the transfer of thermal energy from a hotter to a colder object. What we think of as "cold" is really the absence of heat. An object with at a higher temperature can release more heat than the same object at a lower temperature, but temperature is only one of the factors that affect the amount of heat an object can transfer.

The factors that affect the amount of heat are the same as the factors that affect thermal energy, for reasons that should now be clear to you. Thermal energy is only measurable as heat, during heat transfer. The amount of heat transferred can be found according to the following formula:

amount of heat transferred = mass x change in temperature x specific heat

It is important to note that the symbols that are used for the formula will vary from textbook to textbook, but the values that they represent never change. One way to write the heat transfer formula is shown below:

q = m(DT)Cp

Where q = heat transferred, DT = the change in temperature and Cp = the specific heat.