CWEA Grade I Laboratory Analyst with complete solution
Question : What is chloride?
Correct answer: Major anion found in many natural waters -
Can impart salty taste in H2O
Question : What increases the concentration of chloride in
wastewater?
Correct answer: Chloride in human diet and softeners flushed
into sanitary sewer system
Question : 2 most prevalent methods of measuring chloride?
Correct answer: argentometric and mercuric nitrate
Question : What is the Argentometric method?
Correct answer: Titration of the sample with a standard
solution of silver nitrate (AgNO3) - Indicator: Chromate ions
(CrO4) - End point: reddish silver chromate
Question : What is the Mercuric Nitrate method?
Correct 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 the presence of mercury
Question : Which of the following can be an Interference of
the Mercuric Nitrate Method?
Correct answer: Sulfide, bromide, orthophosphate (over 30
ppm), and iodide
Question : Why does the color change in water?a. Presence of
decaying vegetable matterb. metal ions (ie. iron)c. industrial and domestic pollutiond. All of the above
Correct answer: d
Question : How is color measured
Correct answer: Measured using visual comparison method
Question : What is the visual comparison method
Correct answer: Sample compared to standards using
matching nessler tubes - Standards prepared with solution containing chloroplatinate and cobaltous chlorid
Question : What is the standard unit for color?
Correct answer: One unit= color resulting from 1 mg of
platinum/L
Question : What is 2-color reporting?
Correct answer: True and Apparent
Question : Define True color
Correct answer: Color from suspended solids, determine
using sample treated to remove turbidity
Question : What is Apparent Color?
Correct answer: Color from both dissolved and suspended
solids
Question : What is Conductivity?
Correct answer: H2O capability to pass electrical flow
Question : What is the conductivity of pure water?
Correct answer: 0
Question : What are the Units of conductivity?
Correct answer: µS/cm (micromhos/cm)
Question : What Temperature should conductivity be read at?
Correct answer: 25 degrees Celcius
Question : How is conductivity affected?
Correct answer: Mobility of ions, conductivity is dependent
on viscosity