The Nature of Energy
- There are two types of energy: potential and kinetic.
- Potential energy is stored energy. There are 3 different types of potential energy: elastic, chemical, and gravitational.
- Kinetic energy is the energy of motion.
- The law of conservation of energy states that energy can be converted from one form to another but can be neither created nor destroyed. That is, the energy of the universe is constant.
- Work is force acting over a distance.
Temperature and Heat
- Temperature is a measure of the random motions of the components of a substance. That is, the H2O molecules in warm water are moving around more rapidly than the H2O molecules in cold water.
- Heat is a flow of energy due to a temperature difference.
Exothermic and Endothermic Processes
- The system is the part of the universe on which we wish to focus attention; the surroundings include everything else in the universe.
- When a process results in the evolution of heat, it is said to be exothermic ( exo- is a prefix meaning “ out of”); that is, energy flows out of the system. For example, in the combustion of a match, energy flows out of the system as heat.
- Processes that absorb energy from the surroundings are said to be endothermic. When the heat flow moves into a system, the process is endothermic.
Thermodynamics
- The study of energy is called thermodynamics. The law of conservation of energy is often called the first law of thermodynamics: The energy of the universe is constant.
Calculations
Specific heat capacity:
Hess's Law: