CWEA Grade I Laboratory Analyst Questions and Answers Graded A

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CWEA Grade I Laboratory Analyst Questions and Answers Graded A Chloride ✔✔- Major anion found in many natural waters - Can impart salty taste in H2O What increases concentration of chloride in wastewater ✔✔Chloride in human diet and softeners flushed into sanitary sewer system 2 most prevalent methods of measuring chloride ✔✔argentometric and mercuric nitrate Argentometric ✔✔Titration of sample with standard solution of silver nitrate (AgNO3) - Indicator: Chromate ions (CrO4) - End point: reddish silver chromate Mercuric Nitrate ✔✔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 ✔✔Sulfide, bromide, orthophosphate (over 30 ppm), and iodide Why does color change in water ✔✔Presence of decaying vegetable matter, metal ions (ie. iron) or industrial and domestic pollution How is color measured ✔✔Measured using visual comparison method Visual comparison method ✔✔Sample compared to standards using matched nessler tubes - Standards prepared with solution containing cholorplatinate and cobaltous chloride Standard units for color ✔✔One unit= color resulting from 1 mg of platinum/L 2 color reporting ✔✔True and Apparent True color ✔✔Color from dissolved substances, determine using sample treated to remove turbidity Apparent Color ✔✔Includes dissolved and suspended solids Conductivity ✔✔H2Os capability to pass electrical flow Conductivity of pure water ✔✔0 Units of conductivity ✔✔micromhos/cm Temperature conductivity should be read at ✔✔25 degrees Celcius How is conductivity affected ✔✔Mobility of ions, conductivity is dependent on viscosity Viscosity ✔✔A liquids ability to resist flow, higher the viscosity the lower the flow Relationship of temperature and viscosity ✔✔Inverse Acid ✔✔A compound which liberates hydrogen ions and has a pH below 7. Alkalinity: ✔✔The measurement of a sample's capacity to neutralize acid. Alkalinity measures ✔✔The carbonate, bicarbonate, and hydroxide ion concentration found in water Primary reason for measuring alkalinity ✔✔Used in control of many water and wastewater unit processes How is alkalinity measured ✔✔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: ✔✔The pH is greater than 8.3 Atomic Weight: ✔✔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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