CWEA GRADE 1 LAB ANALYST TEST 2 REAL EXAM
QUESTIONS WITH VERIFIED SOLUTIONS GRADED
A+ TESTED AND APPROVED!!! 2025/2026 NEW
UPDATE
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
Page 1 of 32
,- 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
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.
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,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 oxygenconsuming capacity of
the pollutants present in wastewater. The results of the COD test are not
necessarily related to the BOD, because the chemical oxidant responsible for
utilizing the oxygen may react with substances which bacteria do not stabilize.
Chloride ---- ANSWER----- Major anion found in many natural waters -
Can impart salty taste in H2O
Page 3 of 32
, 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
Page 4 of 32
QUESTIONS WITH VERIFIED SOLUTIONS GRADED
A+ TESTED AND APPROVED!!! 2025/2026 NEW
UPDATE
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
Page 1 of 32
,- 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
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.
Page 2 of 32
,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 oxygenconsuming capacity of
the pollutants present in wastewater. The results of the COD test are not
necessarily related to the BOD, because the chemical oxidant responsible for
utilizing the oxygen may react with substances which bacteria do not stabilize.
Chloride ---- ANSWER----- Major anion found in many natural waters -
Can impart salty taste in H2O
Page 3 of 32
, 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
Page 4 of 32
