Density:
The state or quality of being dense; compactness; closely set or
crowded condition. Mass per unit volume. The mass- that is, the
amount of matter- in a unit volume of any substance. Density is obtained by
dividing the mass of an object by its volume.
Example: Density = mass/volume, or d = m/v
*Excercises
pertaining to Density
Specific gravity:
The ratio of the density of any substance to the density of some other substance
taken as standard, water being the standard for liquids and solids, and hydrogen
or air being the standard for gases.
Vapor pressure:
The pressure exerted by the molecules of a vapor, especially that part of the
total pressure exerted by vapor in a mixture of gases, as by water vapor in
air. The vapor in equilibrium with a liquid, like any gas, exerts a pressure.
A special name is given to the characteristic pressure exerted by this vapor;
it is called the vapor pressure. Magnitudes of vapor pressures, like so many
other properties, vary widely. Liquids with high vapor pressures are said to
be volatile. Those with very low vapor pressures are nonvolatile. Water at ordinary
temperatures is a moderately volatile liquid, at 25°C its vapor pressure
is 23.8 mmHg. Gasoline is a mixture of hydrocarbons, most of which are somewhat
more volatile than water. Whether a liquid is volatile or nonvolatile at a given
temperature is determined primarily by intermolecular forces. As an excellent
first approximation, the vapor pressure of a liquid depends only on its temperature.
*Excercises
pertaining to Vapor Pressure
Partial pressure:
The pressure that a gas in a mixture of gases would exert if it occupied the
same volume as the mixture at the same temperature. John Dalton considered that
in a mixture of gases each gas expands to fill the container and exerts a partial
pressure that is independent of the pressure of other gases. The sum of these
partial pressures is equal to the total pressure of the mixture.
*Calculations
pertaining to Partial Pressure
Capillary action:
A manifestation of surface tension by which the portion of the surface of a
liquid coming in contact with a solid is elevated or depressed, depending on
the adhesive or cohesive properties of the liquid. (Refers to the rise of a
liquid in the pores of thin capillary tubes, a phenomenon related to adhesive
and cohesive forces.)
Adhesion:
The act or state of adhering. The molecular force of attraction in the
area of contact between unlike bodies that acts to hold them together.
Gas Law
P1V1 = P2V2
:
------- ------
T1
T2
Boyle's Law: Found that the volume of a fixed amount of gas maintained at a constant temperature is inversely proportional to the gas pressure. The law that the product of the pressure and the volume of one gram molecule of an ideal gas is equal to the product of the absolute temperature of the gas and the universal gas constant.
Coefficient of expansion:
The fractional change in length, area, or volume per unit change in temperature
of a solid, liquid or gas at a given constant pressure.
Suspension velocity:
The amount of time it takes for the solid particles, which are large enough
to be seen, to settle out on standing, or the velocity the water must have to
suspend a particle.
Settling velocity:
The rate of downward movement of particles through water. This gravitational
settling removes particles naturally and is used also in pollution control devices.
Also used to lower velocity until the particles settle.
Mass/surface area:
Weight/surface area and Mass/surface area are synonomous terms
that show the effects of suspension between a BB and a razor blade. Of
course the razor blade suspends quicker. Also see D.O.
Viscosity:
The property of a fluid that resists the force tending to cause the fluid to
flow. The measure of the extent to which a fluid possesses this property.
(A cup with a hole in it will measure this at a certain temperature.)
% Moisture:
Drying the sample and then weighing gives the dry weight.
Biochemical Oxygen Demand (BOD):
The oxygen required by aerobic organisms, as those in sewage, for metabolism.
The biochemical oxygen demand is a measure of the quantity of dissolved oxygen
consumed in the biological processes associated with the degradation of organic
matter in water. This determination must be carried out according to standardized
procedures. For example, a sample of water is injected with microorganisms and
the mass of dissolved oxygen consumed as organic substances are degraded is
determined after a 5 day period. The higher the BOD, the more polluted a water
sample is considered to be. For one thing, the more oxygen consumed by microorganisms
in degrading organic matter, the less dissolved oxygen is available to support
fish life.
Suspended solids:
Solids which are not in true solution and which can be removed by filtration.
Such suspended solids usually contribute directly to turbidity. Defined
in waste management, these are small particles of solid pollutants that resist
separation by conventional methods. Suspended solids (along with BOD)
is a measurement of water quality and an idicator of treatment plant efficiency.
Alkalinity:
Alkaline condition. The quality that constitutes an alkali. The most striking
feature of bases (alkalis) is their ability to neutralize the characteristic
properties of acids.
Conductivity:
The property or power of conducting heat, electricity, or sound. The quality
of living matter responsible for the transmission of and progressive reaction
to stimuli.
Vanderwaals forces:
Weak, nonspecific forces between molecules. (An equation of state relating
the pressure, volume, and absolute temperature of a gas, taking into account
the finite size of the molecules and the attractive force between them.) Van
der Waals forces is a term used to describe, collectively, intermolecular forces
of the London type and interactions between permanent dipoles.
*Vanderwaals
forces explained further
Ionic bonding:
The electrostatic bond between two ions formed through the transfer of one or
more electrons.
Sulfuric acid:
A clear, colorless to brownish, dense, oily, corrosive, water-miscible liquid,
usually produced from sulfur dioxide. Used chiefly in the manufacture
of fertilizers, chemicals, explosives and dyestuffs and in petroleum refining.
(H2SO4) The use of sulfuric acid in the United States
is so widespread that the vitality of the economy as a whole can be gauged by
the quantity of sulfuric acid consumed. Sulfuric acid production has been termed
a "barometer" of the American economy. Sulfuric acid ranks first among
all manufactured chemicals, with an annual production typically exceeding 40
milltion tons. Principal uses include the manufacture of fertilizers (60%) and
other chemicals (12%), the refining of petroleum (6%) and metals (5%), and the
production of paints and pigments (3%) and rayon and cellulose film (3%).
Hydrochloric acid:
A colorless or faintly yellow, corrosive, fuming liquid, used chiefly
in chemical and industrial processes. (HCl) Also see Muriatic acid.
Alcohol:
A colorless, limpid, volatile, flammable, water-miscible liquid, having an etherlike
odor and pungent, burning taste, used chiefly as a solvent in the extractions
of specific substances.
Sodium hydroxide:
A white, deliquescent, water-soluble solid, usually in the form of lumps, sticks,
chips or pellets that upon solution in water generates heat, produced by the
electrolysis of aqueous sodium chloride. Used chiefly in the manufacture
of organic chemicals, inorganic chemicals, rayon, film, soap, textiles, plastics,
as a laboratory reagent, and in medicine as a caustic, or a base. The annual
U.S. consumption of this substance is about 12 million tons.
Absorption:
The act of absorbing. A taking in or reception by molecular or chemical
action, as of gases or liquids. (The removal of energy or particles from
a beam by the medium through which the beam propagates.)
Reflection:
The return of light, heat, sound, etc. after striking a surface.
Wavelength:
The distance, measured in the direction of propagation of a wave, between two
successive points in the wave that are characterized by the same phase of oscilation.
*Diagram
of a wavelength
Boiling point:
The temperature at which the vapor pressure of a liquid is equal to the pressure
of the atmosphere on the liquid, equal to 212°F (100°C) for water at
sea level.
*Boiling
Point explained further
Freezing point:
The temperature at which a liquid freezes. The freezing point of water
is 32°F, 0°C. Freezing is the conversion of a liquid to a solid. Freezing
of a liquid occurs at the same temperature as melting of the corresponding solid.
Crystalline:
Has a tendancy to form crystals such as salt.
Amorphous:
Lacking definite form; having no specific shape; formless.
Not crystalline. Having structural components that are not clearly differentiated,
as the nucleus material in certain bacteria.
pH:
The symbol for the logarithm of the reciprocal of hydrogen ion concentration
in gram atoms per liter, used to express the acidity or alkalinity of a solution
on a scale of 0 to 14, where less than 7 represents acidity, 7 neutrality, and
more than 7 alkalinity.
*pH
explained further and excercises
Temperature:
A measure of the warmth or coldness of an object or substance with reference
to some standard value. A degree of hotness or coldness measured on a
definate scale.
*Temperature
explained further
Turbidity:
Not clear or transparent because of stirred-up sediment or the like; clouded.
Dissolved oxygen (DO):
The amount of free (not chemically combined) oxygen dissolved in water, wastewater,
or other liquid, usually expressed in milligrams per liter (mg/L), parts per
million (ppm), or percent of saturation. Adequate concentration of dissolved
oxygen are necessary for the life of fish and other aquatic organisms and the
prevention of offensive odors. Dissolved oxygen levels are considered
the most important and commonly employed measurement of water quality and indicator
of a water body's ability to support desirable aquatic life. The ideal
dissolved oxygen level for fish is between 7 and 9 mg/L; most fish cannot
survive at levels below 3 mg/L of dissolved oxygen. Secondary and advanced
wastewater treatment techniques are generally designed to ensure adequate dissolved
oxygen in waste-receiving waters.
Free Oxygen:
Oxygen in a non-combined state. Only combined with itself.
Aerobic:
Requiring the presence of air or free oxygen for life.
Anaerobic:
Living in the absence of air or free oxygen. Scrounging for oxygen in
compounds.
Skin tension:
The tendancy of a liquid to form a relatively tough "skin" or film on its surface.
Surface tension is caused by the attraction between the molecules of the liquid,
and it is surface tension that causes water molecules to stick together and
form drops. Surface tension makes it possible to float a razor blade on
the surface of a glass of water even though the blade is much heavier than the
water.
Super saturated:
To cause (a chemical solution) to be more highly concentrated than is normally
possible under given conditions of temperature and pressure. To cause
(a vapor) to exceed the normal saturation vapor pressure at a given temperature.
Volatile acid:
Evaporates or vaporizes rapidly at room temperature.
Base:
A compound that reacts with an acid to form a salt, as ammonia, calcium hydroxide,
or certain nitrogen-containing organic compounds. The hydroxide of a metal
or of an electropositive element or group.
Molal:
Noting or pertaining to a solution containing one mole or solute per kilogram
of solvent.
Dissolved solids:
The dissolved mineral constituents or chemical compounds in water or solution;
they form the residue that remains after evaporation and drying. Excessive
amounts of dissolved solids make water unfit to drink or use in industrial processes.
Total solids:
A measure of the amount of material that is either dissolved or suspended in
a water sample, obtained by allowing a known volume to evaporate and then weighing
the remaining residue. Total solids equals the sum of the measurements
of Total Dissolved Solids and Total Suspended Solids.
Assay:
To examine or analyze; to know the correct value of a chemical.
Interference:
Something that interferes. Causes false readings.
Covalent bonding:
The bond formed by the sharing of a pair of electrons by two atoms.
Carbonic acid:
The acid formed when carbon dioxide dissolves in water, known in the form of
its salts and esters, the carbonates. (H2CO3)
Nitric acid:
A colorless or yellowish, fuming, suffocating, caustic, corrosive, water-soluble
liquid, HNO3, having powerful oxidizing properties, usually obtained
from ammonia or from Chile saltpeter. Used chiefly in the manufacture
of explosives and fertilizers and in organic synthesis.
Acetone:
A colorless, volatile, water-soluble, flammable liquid, C3H6O,
usually derived by oxidation of isopropyl alcohol or by bacterial fermentation
of carbohydrates. Used chiefly in paints and varnishes as a general solvent,
and in organic synthesis.
Calibration chart:
Calibration involves adjusting a measuring device, such as a pH meter, to a
known value or standard to increase the accuracy of measurements. A calibration
chart is the graphical representation of the measured or observed values of
the instrument opposed to the established or set values of the standard.
A calibration chart is used for determining data when an instrument consistently
reads different from the standard values.
Ammonia:
A colorless, pungent, suffocating, highly water-soluble, gaseous compound, NH3,
usually produced by the direct combination of nitrogen and hydrogen gases.
Used chiefly for refrigeration and in the manufacture of commercial chemicals
and laboratory reagents.
Refraction:
The change of direction of a ray of light, sound, heat, or the like, in passing
obliquely from one medium into another in which its wave velocity is different.
Transmission:
The act or process of transmitting; a sending across.
Visible light:
Spectrum between 450 and 900 nm; visible to the eye.
Ozone:
A form of oxygen, O3, with a peculiar odor suggesting that of weak
chlorine, produced when an electric spark or ultraviolet light is passed through
air or oxygen. It is found in the atmosphere in minute quantities, especially
after a thunderstorm, is a powerful oxidizing agent, and thus biologically corrosive.
In the upper atmosphere it absorbs ultraviolet rays, thereby preventing them
from reaching the surface of the earth. It is used for bleaching, sterilizing
water, etc.
Formaldehyde:
A colorless, toxic, potentially carcinogenic, water-soluble gas, CH2O,
have a suffocating odor, usually derived from methyl alcohol by oxidation.
Used chiefly in aqueous solution, as a disinfectant and preservative, and in
the manufacture of various resins and plastics.
Risk:
Exposure to the chance of injury or loss; a hazard or dangerous chance.
Number damaged
Risk % = ------------------------
x 100
Total # exposed
Settling:
To become fixed, resolved, or established.
Seeding:
A source of development for growth.
Precipitation:
When moist air has risen high enough, water vapor condenses into (Rain, Snow,
and Hail).
Precision:
The accuracy with which a number can be represented. Refers to the degree of
reproducibility of a measured quantity, that is, the closeness of agreement
among the values obtained when the same quantity is measured several times.
Feasibility:
Capable of being used or dealt with successfully.
Coliforms:
Relating to, resembling, or being the colon bacillus.
Velocity:
The rate at which a body moves in space in a given direction. Defined as the
distance traveled per unit of time. An automobile that travels a distance of
60 km in exactly one hour has a velocity of 16.7 m/s.
Stability:
The property of a body that causes it when disturbed from a condition of equilibrium
or steady motion to develop forces or moments that restore the original condition.
Gravity:
The gravitational attraction of the mass of the earth, the moon, or a planet
for bodies at or near its surface.
Bedding:
Substance used to support, filter or cushion foreign objects from entering the
earth's soil.
Turbulence:
Irregular atmospheric motion especially when characterized by up-and-down currents.
Inertia:
The process of making an object that is not moving continue motionless unless
some force puts it into motion.
Volume:
The amount of space an object occupies. Volume is an important property, but
it is not as fundamental as mass because volume varies with temperature and
pressure, whereas mass does not. Volume has the unit (length)3. The basic unit
of volume in the metric system is the cubic meter. Another commonly used unit
is the cubic centimeter and still another is the liter.
Erosion:
The action or process of eroding
Energy:
Defined as the capacity to do work, but there are further ways of categorizing
energy beyond this simple statement. For example, an object in motion has the
immediate capacity to do work, and its energy is called kinetic energy. An object
at rest may also have the capacity to do work by changing its position. The
energy it possesses, which can be transformed to actual work, is called potential
energy. As a ball rolls down a hill, some of its potential energy is converted
to kinetic energy. The kinetic energy of an object is given by one-half the
product of its mass and the square of its velocity. (KE = 1/2 mv2).
Mathematical expressions for potential energy are also possible, but their exact
forms depend on the manner in which this energy is "stored".
Infiltration:
The effect of reducing the capacity of the sewer for conveying the waste flows
for which it was designed.
Pressure:
Force per unit area.
Example: At sea level the atmospheric pressure
is 14.7 pounds per square inch, this decreases with altitude because of less
air pressing from above.