CWEA Grade I Laboratory Analyst exam with 100% Correct answers 2025/2026

CWEA Grade I Laboratory Analyst exam with 100% Correct answers 2025/2026 Chloride - answer-- Major anion found in many natural waters - Can impart salty taste in H2O 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 - 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