Asolution of a specific vitamin has ? max = 275 nm and a concentration of 2.71 × 10-7 m. the absorbance of the solution at 275 nm is a = 0.150. what is the molar absorptivity of the vitamin at 275 nm? (sample pathlength = 1.00 cm)

Which substances have the lowest melting points: ionic covalent, or metallic

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.