Lab 5: Physical and Chemical Analysis of Water
In this lab we will focus primarily on chemical characterization, examining some of the factors
that impact the quality of water, both for drinking and as a habitat for aquatic organisms.
Additionally, two physical properties, conductivity and specific gravity, will also be measured.
Each student will research, analyze, and compare (using the World Wide Web) eight water
1) Tap water: Tap water is the water that you get directly from your faucet, it may or may
not be suited for drinking purposes.
2) Mineral water: Mineral water is the water that naturally contains minerals. It is obtained
from underground sources, which makes it rich in minerals like calcium, magnesium,
3) Spring water: In some places, rainwater accumulated underground tends to “leak” out at
the surface as a spring, or puddle. Natural springs are not passed through a community
water system and are yet considered suitable for drinking as it comes from under the
4) Well water: When it rains, water trickles down and travels through the inner crevices of
the soil, beneath the ground to form underground lakes. This happens over a period of
time. In rural areas, one of the primary sources of water is what is dug out from deep
wells. Deep wells directly tap groundwater and bring it to the surface from which people
can take their water.
5) Purified water: A purified water is the water which after deriving from its source has
underwent purification treatment in a plant.
6) Distilled water: Distilled water or demineralized water is one where the water has been
subjected to a treatment that removes all its minerals and salt by the process of reverse
osmosis and distillation.
7) Sparkling water: Sparkling water is the water that has undergone carbonation which
makes your water fizzy just like your sodas.
8) Salt water: Seawater, or salt water, is water from a sea or ocean.
Conductivity is an expression of the ability of a water sample to carry electrical current. This
number depends on the total concentration of ionized substances dissolved in water and the
temperature at which the measurement is taken. The mobility of each ion, their charge and their
concentrations with respect to each other also affect conductivity. Ions in water are usually
substances such as salts; therefore the conductivity is also a measure of the salinity (saltiness) of
the water. Conductivity is measured in micro Siemens (S).
2) Specific Gravity
This physical property is a measure of the density of the water sample. Pure water at 25 oC has a
density of 1.000 g/ml (or g/cc); a value different from that suggests the presence of material that
increase the density of the water sample.
Chemical properties (Dissolved Materials)
1. pH: The pH of a material is the measure of its acid or base properties. As you might recall
from last week’s lab, acids are materials with hydrogen ions present that dissolve in the water
and release those H+ ions. Bases produce hydroxide (OH-) ions when dissolved in water. (Note
that acids and bases, by definition, do not exist in any other form except dissolved in water. It is
the presence of H+ or OH- in a water solution that defines the acid or base.) When exposed to
each other acids and bases undergo "neutralization" in which the H+ and OH- combine to make
2. Carbon Dioxide: Carbon dioxide readily dissolves into water producing carbonate and
bicarbonate salts like baking soda (sodium bicarbonate NaHCO3) or calcium carbonate CaCO3,
the material responsible for what we refer to as water hardness.
3. Dissolved oxygen: The quantity of oxygen gas dissolved in water is extremely important, as
it is the main constituent to determine the presence of aquatic life. Underwater life relies on
water to absorb oxygen gas for their use. Too little or too much oxygen interferes with this
To turn in:
Design a data table with the columns for pH measurement, conductivity, specific gravity, CO2
concentration, and dissolved O2 concentration. Record the data for each water sample in the
table. Write a formal lab report [intro, M&M, results, discussion, conclusion, lit cited (4- 6
pages)] comparing the different water samples, interpreting the results in your data table. Are
the results for the different water samples what you expected?
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