CWEA LAB ANALYST COMPLETE SET Questions and Correct Solutions 2024/2025

CWEA LAB ANALYST COMPLETE SET Questions and Correct Solutions 2024 An amperometric titration is often used when measuring - Answer -Residual chlorine The most important reason for chlorinating effluent is - Answer -Disinfection Chlorination serves primarily to destroy or deactivate disease-producing microorganisms When wastewater samples are chlorinated and the pH is lowered - Answer -HCLO is formed Hypochlorous acid Which of the following constituents is the best disinfecting agent? - Answer -HClO What is most likely to interfere with the DPD test? - Answer -Oxidized manganese How is N, N-diethyl-p-phenylenediamine more commonly represented? - Answer -DPD The chlorine residual may be determined using the reagent - Answer -DPD The quantity of chlorine that is converted to inert or less active forms of chlorine by substances in wastewater - Answer -Total combined chlorine Before you perform an amperometric titration for total residual chlornie, what two solutions should be added to the sample? - Answer -Kl and acetate buffer (Potassium iodide) When performing an amperometric titration for chlorine, how many milliliters of sample should be analyzed? - Answer -200 mL When using a spectrophotometer to measure chlorine, what wave length of light should be used? - Answer -515 nm An effluent with a high level of ammonia nitrogen has chlorine residual that is mostly - Answer - Combined chlorine The mercuric nitrate titration technique for measuring chloride is falling into disuse in the laboratory because the: - Answer -technique is lengthy and requires highly skilled instrument technicians to accurately analyze the samples.Standard phenylarsine oxide solution (PAO): - Answer -should be handled with caution because it is a severe poison. Sample Protocol for chloride includes - Answer -glass or plastic container with no preservative Flow proportional sample. If total sample volume is 1 liter - Answer -100ml The incubator for the BOD determination should be monitored and recorded daily. The incubator temperature should be: - Answer -20 degrees +/-1 degree C Laboratory data mistakes may be corrected by: - Answer -lining out the mistake with pen and writing the correct answer to the side of the first with analyst initials and date The sample receiving log must record time and date sampled: - Answer -sample collector, nature of sample, analyses to be performed, preservatives, condition of sample and sample recipient. Hood flow should be monitored and documented at: - Answer -100 linear feet per minute During an acid base titration, the titrant is added to the sample with a: - Answer -Buret Separatory funnels are designed to facilitate liquid-liquid extractions. Liquid-liquid extraction can be used to separate - Answer -organic analytes from the water by partitioning them into an organic solvent At a given temperature the intensity of the acidic or basic character of a solution is indicated by - Answer -pH or Hydrogen ion activity A solution with a pH of 5 has a concentration of hydrogen ions that is how many times higher than a solution with a pH if 7? - Answer -100 times higher A pH measurement requires the following: - Answer -a voltmeter, glass pH electrode, reference electrode, and temperature compensating device Conductance measurements are temperature compensated to: - Answer -25.0 C The conductivity meter is calibrated with: - Answer -.0100 N potassium chloride standard Alkalinity is reported as: - Answer -alkalinity, mg CaCO3/L The hardness determination by EDTA titration measures: - Answer -Calcium and Magnesium The indicator for the hardness determination is: - Answer -eriochrome Black T EPA acceptable primary standards for the turbidity determination include: - Answer -formazine only COD - Answer -((Blank-Sample) x M x 8000))/ml SampleThe Biochemical Oxygen Demand determination is an empirical test in which standardized laboratory procedures are used to: - Answer -determine the relative oxygen requirements of wastewaters, effluents and polluted waters. Sample pretreatment for the BOD determination includes - Answer -assuring that the samples are neutralized to a pH range between 6.5 and 7.5 and that any residual chlorine has been dechlorinated The process designed to kill most microorganisms in wastewater, including essentially all pathogen