Title: Introductory Chemistry: A Foundation, 6th Ed. Introductory Chemistry, 6th Ed. Basic Chemistry, 6th E
1Chapter 10Energy
2What is Ahead?
- To understand the general properties of energy.
- To understand the concepts of temperature and
heat. - To understand the units of energy.
- To consider the energy resources of our world.
3Energy
- Energy Capacity to do work or supply energy.
- 1. Potential Energy stored energy.
- Example a coiled spring have potential energy
waiting to be released. - 2. Kinetic Energy energy of motion.
- Example when the spring uncoil potential energy
is converted to the kinetic energy.
4Figure 10.1 (a) In the initial positions, ball A
has a higher potential energy than ball B. (b)
After A has rolled down the hill, the potential
energy lost by A has been converted to random
motions of the components of the hill
(frictional heating) and to an increase in the
potential energy of B.
5Conservation of Energy
- Just like matter, energy cannot be created or
destroyed but it can converted from one form to
another. - This is the law of conservation of energy.
- There are six forms of energy heat, light,
electrical, mechanical, chemical, and nuclear.
6Forms of Energy
- Kinetic energy
- Potential energy
- Solar energy
- Radiant energy
- Thermal energy
- Nuclear energy
- Electrical energy
- Chemical energy
7Energy Conversion
- Identify the energy conversions in each of the
following - Radioactive uranium vaporizes water to steam.
_________ - Steam drives a turbine. ___________
- A turbine spins and drives an electrical
generator. __________ - Flashlight. ___________
- Solar calculator. ____________
- Lead-acid battery. ___________
- Electrical heater. ____________
8Answers
- Radioactive uranium vaporizes water to steam.
Nuclear to thermal. - Steam drives a turbine. Thermal to mechanical.
- A turbine spins and drives an electrical
generator. Mechanical to electrical. - Flashlight. Chemical to radiant.
- Solar calculator. Radiant to electrical.
- Lead-acid battery. Chemical to electrical
- Electrical heater. Electrical to thermal.
9Temperature and Heat
- Temperature is a measure of the random motion of
the components of a substance. - Heat a flow of energy due to a temperature
difference.
10Figure 10.3 The H2O molecules in hot water have
much greater random motions than the H2O
molecules in cold water.
11Figure 10.4 The water samples have the same
temperature (50. C) and have the same random
motions.
12Units of Energy
- calorie (cal metric system unit) the amount of
energy required to raise the temperature of one
gram of water by one Celsius degree. - Units are
- calorie (cal) and joule (J)
- 1 cal 4.184 J, 1 kcal 4.184 k
- 1000 cal 1 kcal (kilocalorie)
- 1000 J 1 kJ
- Calorie (food calorie 1 Cal 1000 cal)
13Specific Heat
- The specific heat of a substance is the amount of
heat required to bring about a change in
temperature. - The larger the specific heat, the more heat is
required to raise the temperature of the
substance.
14Examples of specific heat
Iron 0.108 cal/g.degree Copper 0.0920
cal/g.degree Water 1.00 cal/g.degree Air 0.241
cal/g.degree
15Food Calories
- Medium size Candy bar contains 240 Calories.
That is 240,000 calories or about 1.0 million
joule. The fact of the matter is, that it takes
1 joule of energy to lift 1 small apple of 1
Newton weight (about 0.25 pound) for a distance
of 1 meter. That concludes, some one should lift
that apple one million times for a distance of 1
meter to be able to burn all the calories
generated from the snack bar.
16- Candy Serving Size Calories
- Chocolate coated peanuts 1oz 155
- Hershey bar 1 (1.5oz) 240
- Hershey kisses 9 (1.5oz) 220
- M M's, plain 1 pkt 230
- M M's, peanut 1 pkt 250
- Skittles 1 pkt (2.8oz) 250
- Snickers bar 1 bar (2.1oz) 280
17Energy and Our World
- Petroleum and natural gas
- Coal
- New energy sources
18Hydrocarbons
19Methane molecule
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21Figure 10.7 Energy sources used in the US.
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23Coal is an important and plentiful fuel in the
United States, currently furnishing approximately
20 of our energy.
Corbis
24Figure 10.8 The function of the earth's
atmosphere.
25Figure 10.9 The atmospheric CO2 concentration
over the past1000 years, based on ice core data
and direct readings (since 1958).