# Chemistry Chapter 6 Notes Essay

7179 WordsJun 21, 201329 Pages
06.01 Thermochemistry Temperature and Thermal Energy Temperature is a measure of the average kinetic energy of the particles in a sample of matter. The greater the average kinetic energy of the particles in a sample of matter, the higher the temperature of that matter. To assign a numerical value to temperature, scientists use defined temperature scales (Fahrenheit, Celsius, and Kelvin). Temperature is a measure of average kinetic energy, but thermal energy is the measure of the total kinetic energy in a sample. Both involve the kinetic energy of the particles in a substance, so what exactly is the difference between the two? To understand the difference, let’s compare a bathtub of warm water to a coffee cup of boiling water. Heat Heat can be described as the transfer of thermal energy from one substance to another due to the temperature difference between the two substances. A sample of matter can have a certain amount of thermal energy, but the matter does not have heat. Heat is the movement, or flow, of thermal energy. Heat always flows spontaneously from matter at a higher temperature to matter at a lower temperature. In the experiment that you did at the beginning of this lesson, you experienced the flow of thermal energy in two different directions. Your hand that felt cold felt that way because heat was flowing from your hand to the water because the water was at a lower temperature than your hand. Your other hand felt warm in the water because heat was flowing to your hand from the water, because that hand was at a lower temperature than the water. Energy flow depends on temperature difference, not on the difference in total thermal energy of the two substances. This flow of thermal energy will continue until both substances are at the same temperature. Heat and thermal energy are both measured in units of energy. The SI unit for energy that is