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CWEA GRADE 1 LAB ANALYST EXAM ACTUAL
EXAM 200 QUESTIONS AND CORRECT
DETAILED ANSWERS WITH RATIONALES
|AGRADE
**Question 1: What is chloride and what effect can it have on
water?**
Answer: Chloride is a major anion found in many natural waters
and can impart a salty taste in H2O.
**Question 2: What increases the concentration of chloride in
wastewater?**
Answer: Chloride in human diet and softeners flushed into
sanitary sewer system.
**Question 3: What are the two most prevalent methods of
measuring chloride?**
Answer: Argentometric and mercuric nitrate.
**Question 4: How does the argentometric method measure
chloride?**
Answer: Titration of sample with standard solution of silver
nitrate (AgNO3); Indicator: Chromate ions (CrO4); End point: reddish silver chromate.
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**Question 5: How does the mercuric nitrate method measure
chloride?**
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.
**Question 6: What substances interfere with the mercuric
nitrate method for measuring chloride?**
Answer: Sulfide, bromide, orthophosphate (over 30 ppm), and
iodide.
**Question 7: Why does color change in water?**
Answer: Presence of decaying vegetable matter, metal ions (ie.
iron) or industrial and domestic pollution.
**Question 8: How is color in water measured?**
Answer: Measured using visual comparison method.
**Question 9: What is the visual comparison method for
measuring color?**
Answer: Sample compared to standards using matched nessler
tubes; Standards prepared with solution containing chlorplatinate and cobaltous chloride.
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**Question 10: What is the standard unit for color in water?**
Answer: One unit = color resulting from 1 mg of platinum/L.
**Question 11: What are the two types of color reporting in
water?**
Answer: True and Apparent.
**Question 12: What is true color in water?**
Answer: Color from dissolved substances, determined using
sample treated to remove turbidity.
**Question 13: What is apparent color in water?**
Answer: Includes dissolved and suspended solids.
**Question 14: What is conductivity in water?**
Answer: H2Os capability to pass electrical flow.
**Question 15: What is the conductivity of pure water?**
Answer: 0
**Question 16: What are the units of conductivity?**
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Answer: micromhos/cm
**Question 17: At what temperature should conductivity be
read?**
Answer: 25 degrees Celsius
**Question 18: How is conductivity affected?**
Answer: Mobility of ions, conductivity is dependent on
viscosity.
**Question 19: What is viscosity?**
Answer: A liquids ability to resist flow, higher the viscosity the
lower the flow.
**Question 20: What is the relationship of temperature and
viscosity?**
Answer: Inverse
**Question 21: What is an acid?**
Answer: A compound which liberates hydrogen ions and has a
pH below 7.