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CWEA Grade I Laboratory Analyst Exam 2023
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CWEA Grade I Laboratory Analyst Exam 2023
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CWEA Grade I Laboratory AnalystExam 2023
Chloride - Answer - Major anion found in many natural waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater - Answer Chloride in human
diet and softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride - Answer argentometric and
mercuric nitrate
Argentometric - Answer Titration of sample with standard solution of silver nitrate
(AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
Mercuric Nitrate - Answer Titration with standard mercuric nitrate solution
-pH must be adjusted between 2.3 and 2.8
- Indicator: Diphenyl carbazone
- End point: Change from blue to purple in presence of mercury
Interference of Mercuric Nitrate Method - Answer Sulfide, bromide, orthophosphate
(over 30 ppm), and iodide
Why does color change in water - Answer Presence of decaying vegetable matter,
metal ions (ie. iron) or industrial and domestic pollution
How is color measured - Answer Measured using visual comparison method
Visual comparison method - Answer Sample compared to standards using matched
nessler tubes
- Standards prepared with solution containing cholorplatinate and cobaltous chloride
Standard units for color - Answer One unit= color resulting from 1 mg of platinum/L
2 color reporting - Answer True and Apparent
True color - Answer Color from dissolved substances, determine using sample
treated to remove turbidity
Apparent Color - Answer Includes dissolved and suspended solids
Conductivity - Answer H2Os capability to pass electrical flow
Conductivity of pure water - Answer 0
Units of conductivity - Answer micromhos/cm
Temperature conductivity should be read at - Answer 25 degrees Celcius
, CWEA Grade I Laboratory Analyst
Exam 2023
How is conductivity affected - Answer Mobility of ions, conductivity is dependent on
viscosity
Viscosity - Answer A liquids ability to resist flow, higher the viscosity the lower the
flow
Relationship of temperature and viscosity - Answer Inverse
Acid - Answer A compound which liberates hydrogen ions and has a pH below 7.
Alkalinity: - Answer The measurement of a sample's capacity to neutralize acid.
Alkalinity measures - Answer The carbonate, bicarbonate, and hydroxide ion
concentration found in water
Primary reason for measuring alkalinity - Answer Used in control of many water and
wastewater unit processes
How is alkalinity measured - Answer Titration of a sample with a standard solution of
either sulfuric acid or hydrochloric acid to predetermined pH endpoint
The phenolphthalein alkalinity of a water sample is zero if: - Answer The pH is
greater than 8.3
Atomic Weight: - Answer The sum of the number of protons and the number of
neutrons in the nucleus of an atom.
Atomic weights of elements are found on periodic tables.
Base: - Answer A compound which liberates hydroxide ions and has a pH above 7.
Biochemical Oxygen Demand (BOD): - Answer The quantity of oxygen utilized in the
biochemical oxidation of organic
matter under standard laboratory procedures for five days at 20° Centigrade, usually
expressed as a
concentration (e.g., mg/L). BOD measurements are used to indicate the organic
"strength" of wastewater.
Chain-of-Custody: - Answer A legal record (which may be a series of records) of
each person who had possession of an environmental sample, from the person
releasing the sample, to the person who collected the sample, to
the person who analyzed the sample in the laboratory, to the person who witnessed
the disposal of the
sample.
Chemical Oxygen Demand (COD): - Answer The amount of oxygen (expressed in
mg/L) consumed from the oxidation
of pollutants during a specific test. As such, COD is a measure of the oxygen-
consuming capacity of the
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