The Chemicals in Your Life
Chemistry is the study of matter and the changes that it undergoes.
1. Devise experiments to test
2. Data needs to be collected to prove the hypothesis
1. Well tested, many observations have been made
2. Must be verified by others.
- the earth is round,
- water boils at 100*C (near sea level),
- 90% of the emphysema cases are caused by smoking
Large amounts of data have been accumulated to formulate a law that applies to many similar situations.
The first law of thermodynamics:
D. Theories are tentative, there are some facts to support them, but not enough to make a law.
Energy can be changed from one form to another, but it can not be created nor destroyed.
(Please read page 410, for more information)
The second law of thermodynamics:
Energy flows from a warm object to a cold object.
Law of conservation of mass
Natural processes go towards higher disorder.
Entropy is a measure of disorder in the universe.
The entropy of the universe is increasing.
Energy is needed to combat entropy.
(Please read page 411 for more information)
Lavoisier (A.D. 1700) was a tax official for King Louis XVI.
Matter is neither created nor destroyed during a chemical change.
The mass of starting materials equals the mass of products.
Pictures represent processes that are too small to see.
Models are testable, explanatory and tenative.
Cigarette tar binds to DNA and makes reactive molecules that cut DNA. This DNA damage may lead to cancer.
The amount of uncertainty in measuring data increases from math to biology to the social sciences.
There is more variability in test tubes than with calculations on paper, more variability with cells than test tubes, more variability with rats than cells and more variability with humans than rats.
It is more difficult and more expensive to do experiments with humans, but do the results from rat experiments extrapolate to humans? Can the results of a test tube experiment predict what will happen in humans? The answer is, "sometimes".
II. Matter and Energy
Matter is mass, it is a quantity that does not change regardless of the location.
Weight is a force. Force varies with gravity. You weigh more on land than you do in a swimming pool. You would weigh less on the moon, if you had the opportunity to go to the moon.
A. Physical and chemical changes
- how one substance reacts with another
- gasoline + oxygen produces carbon dioxide and water and energy
- same chemical, different form
- boiling, melting are physical changes
C. States of Matter: Solids, Liquids, Gases
kinetic energy (energy of motion)
- light energy
- heat energy
- mechanical energy
D. Pure substances
- Solids have definate shapes and volumes.
- Liquids change shape according to the container, but have constant volumes.
- Gases change shape and volume, it expands to fill its container.
2. compounds, two or more elements, in fixed proportions
- water, H2O
- salt, NaCl
- sugar, C12H24O11
1. Homogeneous: same throughout
2. Heterogeneous, different
b. sugar water
a. ice water
c. rootbeer float
A. SI units: meter, kg
B. metric prefixes:
1. mega, kilo, centi, milli, micro
C. volume: cm3, mL
E. Temperature: degrees centigrade, degrees Kelvin (SI unit)
1. 9/5C+32 = F
2. 5/9(F - 32) = C
3. C + 273 = K
IV. Central Role of Chemistry
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Copyright © 1996 Koni Stone