LaMotte ACID RAIN STUDY OUTFIT ARO - Manual (Page 3)

Leaf Margin - The border or edge on a leaf. A leaf margin may take many shapes or
forms such as smooth, saw-like, or tooth-like.
Litmus Paper
- Paper which is soaked in a coloring matter obtained from primitive
plants called lichens. In alkaline solution litmus turns blue; in an acidic solution
litmus turns red.
Mineral Deficiency Disease - A disease in plants which is caused by the lack of one
or more of the important plant nutrients.
Neutral - A substance that is neither acidic nor basic but having a pH of 7.0 on the
pH scale.
Nitrogen Oxides - Gaseous compounds of oxygen and nitrogen which can
contribute to air pollution.
Nutrient, Plant - Any element taken in by a plant which is essential to its growth.
Nutrients are used by the plant to produce food and tissue.
Organic Matter - Animal and plant materials that are decomposed through the
action of micro-organisms.
Oxidation - The process by which oxygen combines with other compounds to
change their chemical state.
pH
- The concentration of hydrogen ions in a substance. A pH scale is used to
indicate whether a substance is acidic, neutral, or basic.
Plankton - Very small plants and animals that live in water.
Pollution - The presence of matter or energy whose nature, location, or quantity
produces undesired environmental effects.
Root Hairs - Very small roots of plants which take up nutrients from the soil
solution.
Run-off - The portion of precipitation or snow melt that runs off the land into
streams or other surface water.
Solution - One or more substances dissolved in a liquid.
Sediments - Soil, sand, and minerals that wash from the land into water and settle
to the bottom of streams and lakes.
Smelter - A facility that melts or fuses ore to separate metals.
Sulfur Dioxide (SO
2
) - A heavy, pungent, colorless and gaseous air pollutant.
Surface Water - All water naturally open to the atmosphere (rivers, lakes, reservoirs,
streams, impoundments, seas, estuaries, etc.); also springs and wells which are
directly influenced by surface water.
Weathering - The disintegrating action of the elements (wind, rain, sleet, snow,
freezing, and thawing) on rocks and soils.
14
pH
The pH of a liquid, soil or other substance indicates whether a substance is acidic,
neutral, or basic. The pH measurement is based on the number of hydrogen ions
(H
+ ) or hydroxyl ions (OH - ) there are in a solution of the substance. If the solution
has more hydrogen ions than hydroxyl ions, the solution is acidic. On the other
hand, if the hydroxyl ions outnumber the hydrogen ions, the solution is basic. When
both the hydrogen ions and hydroxyl ions are present in equal numbers, the solution
is neutral.
THE pH SCALE
The pH scale ranges from 0
(very acid) to 14 (very
alkaline or basic). On this
scale a neutral substance is
7 (the mid-point of the
scale), an acid substance is
lower than 7 on the scale,
and a basic or alkaline
substance is higher than 7
on the scale. (Fig. 1 )
When an acid and a base
react, neutralization occurs.
The result is a solution that
is not as acidic or as basic as
the original substances. It is
important to know that the
pH scale is logarithmic.
Every one-unit change in
pH represents a ten-fold
change in acidity or
alkalinity. In other words,
pH 6 is ten times more
acidic than pH 7; pH 5 is
one hundred times more
acidic than pH 7. Pure
distilled water has a pH of 7
but quickly becomes slightly
acidic when exposed to air.
This is also the case with
rain water in the
atmosphere.
3
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
BASIC
NEUTRAL
ACIDIC
Household Lye
Bleach
Ammonia
Milk of Magnesia
Borax
Baking Soda
Blood
Distilled Water
Milk
Boric Acid
Orange Juice
Vinegar
Battery Acid
Fig. 1 The approximate pH values of some common substances.