Chemistry      Physical Science        Mr. Seegers


Chemistry
- Deals with the composition and structure of matter (anything with mass)
and the reactions by which substances are changed into other substances.

Matter - anything that has mass

2 types of matter
Pure Substance and Mixture

Pure Substance
- matter with fixed composition and properties

Elements
- substance in which all the atoms have the same
number of protons (same atomic number)
Compound
-substance composed of 2 or more elements chemically
combined in definite fixed ratio by mass

Mixture
- Type of matter composed of varying proportions of two or more
substances that are just physically mixed, not chemically combined

Homogeneous Mixture
- uniform throughout

Heterogeneous Mixture
- non uniform

Solvents
- substance present in the larger amount
ex. water in kool-aid

Solute
- substance present in the smaller amount
ex. the kool-aid powder

Aqueous Solution
- solution in which water is the solvent
ex. tea
- can be Unsaturated or Saturated
Unsaturated
- if more solute can be dissolved in solution
Saturated
- the maximum amount of solute is dissolved
Super Saturated
- more than maximum of solute present
- results in undissolved solute

A neutral solution:
Has a pH of exactly 7.
Contains equal amounts of hydronium ions and hydroxide ions.
Pure Water is neutral

An acid solution:
Has a pH lower than 7.
Contains more hydronium ions than hydroxide ions.
The farther from 7, the stronger the acid.

A basic solution:
Has a ph higher than 7.
Contains more hydroxide ions than hydronium ions.
The farther from 7, the stronger the base.

Indicators:
Compounds that show a color change in an acid or base.
Most indicators are weak organic acids or bases that react with ions in solution.
It is this chemical reaction that produces the color change.
Indicators are used to determine the approximate pH of a substance.

Most common indicator is:
Litmus -
Acids turn blue litmus red.
Bases turn red litmus blue.

pH Meter: A device used to measure the exact pH of a solution.

Living Matter:
All living matter is comprised of

65% oxygen
18% carbon
10% hydrogen
3% nitrogen
4 % traces of the other elements

Occurrence of Elements in earth’s crust

Oxygen 47%
Silicon 27%
Aluminum 8%
Iron 5%
Calcium 3.5%
Sodium 3%
Potassium 2.5%
Magnesium 2%

Environmental Chemistry

Acid rain
- caused by the burning of coal

- burning produces gases (sulfur and nitrate impurities)

- sulfur impurity chemically combines with oxygen to form sulfur dioxide and sulfur trioxide

-gases can cause breathing difficulties if allowed to accumulate in the atmosphere.

-Lung ailments such as emphysema can result as these gases settle in the lungs

-gases remain in the atmosphere until they are "leached" out by coming into contact
with rain that dissolves the gases forming Sulfurious and Sulfuric acid droplets.

-collect in the water table beneath the surface or runoff into streams finally
collecting in lakes and eventually making their way to the oceans.

-acid rain drastically alters the pH of lakes which can adversely affect the ecological
balance of aquatic life

-many species of marine life cannot thrive outside of a pH range. In addition, increasing
the acidity of the waterways can cause certain marine life to thrive which eventually
results in threatening other aquatic forms of life both plant and animal.

-can be corrected by scrubbing coal which removes the sulfur impurities

Other Effects

Acid rain also seems to have a negative effect on architectural buildings and works
of art that are constructed of Calcium Carbonate (marble).

Calcium Carbonate reacts upon contact with the acid droplets to produce Carbonic acid

Carbonic acid - a weak and unstable acid that will further decompose to Carbon Dioxide and Water.
-The carbon dioxide will diffuse into the atmosphere.

Carbon Dioxide in the atmosphere?
-not all Carbon Dioxide is bad and should be curtailed
-Carbon Dioxide is essential to life itself and forms a part of the natural cycle
called the Carbon cycle.

Carbon Dioxide is an essential ingredient in the photosynthetic process of plants
       CO2 + H2O + sunlight -----> glucose (sugar) + Oxygen

In order for nature to supply this carbon dioxide it must be produced by respiration
which both plants and animals undergo:
              glucose + Oxygen ------> CO2 + H2O

-if normal balance is maintained no problems occur

-industrialization and deforestation have contributed to an imbalance resulting in a
gradual increase of the total Carbon Dioxide in the atmosphere.

Other Concerns
-incomplete combustion (occurs when combustible fuels do not receive enough Oxygen gas)
Carbon Monoxide which is toxic.

With the presence of Carbon Monoxide, Oxygen is blocked from forming the hemoglobin complex.
This prevents the Oxygen from reaching the body's cells resulting in oxygen depletion.
-at higher concentrations the brain cells have Oxygen depletion and loss of consciousness,
coma, and eventually (if not corrected) death.

- only reversal to this condition is to reach the victim in time and to administer large
doses of Oxygen rich air into the victim's lungs

What effect does increased CO2 have?

-our sea levels and our weather patterns and could ironically introduce a new ice age prematurely.
Called the greenhouse effect.

- CO2 increase in the atmosphere will result in more radiation remaining on the earth.

- increase in Infrared energy will have a warming effect on the earth's surface over a period of time.

- although gradual it does not take a large increase in temperature of the earth to cause the
ice caps to begin melting at a faster rate.

This will result in at least four problems:

1. significantly increase the sea levels on the coastal regions thereby flooding all coastal regions and changing
the land mass area

2. could decrease the ice caps thereby reducing the ability of the ice caps to reflect further
radiation out into space.

3. could increase the water surface area and the amount of liquid water which will absorb more
energy causing a counteractive "cooling" trend (ie: ice age phenomenon)

4. could alter the weather patterns thus changing the weather zones. The tropic zone will
move north. Would result in a further reduction in the polar ice caps.

How to reverse the Greenhouse Effect?
- increase in the number of trees (reducing the carbon dioxide and replenishing the Oxygen supply)
reduce burning of fossil fuels.