Chemistry, 10.11.2019 23:31 micahmckay05
To determine the ammonia concentration in a sample of lake water, three samples are prepared. in sample a, 10.0 ml of lake water is mixed with 5 ml of phenol solution and 2 ml of sodium hypochlorite solution, and diluted to 25.0 ml in a volumetric flask. in sample b, 10.0 ml of lake water is mixed with 5 ml of phenol solution, 2 ml of sodium hypochlorite solution, and 2.50 ml of a 5.50×10−4 m ammonia solution, and diluted to 25.0 ml. sample c is a reagent blank. it contains 10.0 ml of distilled water, 5 ml of phenol solution, and 2 ml of sodium hypochlorite solution, diluted to 25.0 ml. the absorbance of the three samples is then measured at 625 nm in a 1.00 cm cuvet. the results are shown in the table. sample absorbance (625 nm)a 0.419b 0.666c 0.045what is the molar absorptivity of the indophenol =m−1cm−1what is the concentration of ammonia in the lake water? [nh3]lake water=m
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