0.16 Bis2a 04.0 energy and thermodynamics v1.2  (Page 7/21)

Art connection

If no activation energy were required to break down sucrose (table sugar), would you be able to store it in a sugar bowl?

Lowering the activation energy:

1. makes the reaction happen faster
2. lowers the energy level of the transition state
3. is accomplished by adding a catalyst to the reaction
4. always causes more product to be produced
5. only reduces the transition state energy level in one direction, from reactants to products
6. a, b and c
7. b and c
8. all of the above are true

g

Conservation of energy

Though energy can be converted from one form to another, energy cannot be created or destroyed. This principle is called the "law of conservation of energy." For example, in a motorcycle, the chemical potential energy of the fuel changes to kinetic energy. In a radio, electricity is converted into kinetic energy and wave energy (sound).

Machines can be used to convert energy from one form to another. Though ideal machines conserve the mechanical energy of a system, some of the energy always turns into heat when using a machine. For example, heat generated by friction is hard to collect and transform into another form of energy. In this situation, heat energy is usually considered unusable or lost.

Energy sources

The source of energy for many processes occurring on the earth's surface comes from the sun. Radiating solar energy heats the earth unevenly, creating air movements in the atmosphere. Therefore, the sun drives the winds, ocean currents and the water cycle. Sunlight energy is used by plants to create chemical energy through a process called photosynthesis, and this supports the life and growth of plants. In addition, dead plant material decays, and over millions of years is converted into fossil fuels (oil, coal, etc.).

Today, we make use of various sources of energy found on earth to produce electricity. Using machines, we convert the energies of wind, biomass, fossil fuels, water, heat trapped in the earth (geothermal), nuclear and solar energy into usable electricity. The above sources of energy differ in amount, availability, time required for their formation and usefulness. For example, the energy released by one gram of uranium during nuclear fission is much larger than that produced during the combustion of an equal mass of coal.

For this class, it is important for you to be able to identify the energy source for living cells. Whether we are discussing organisms such as trees or dogs, or individual cells, such as muscle or brain cells, or free living cells, such as bacteria or yeast, all cells need an energy source. Being able to identifying the cellular energy source will be one of the goals of this class. In addition most metabolic reactions require an energy source as well. Identifying and applying these concepts will be a major focus of this course.

US ENERGY PRODUCTION (Quadrillion BTU)