Experiment 1 Assay of Alum Questions 1. What is gravimetric method? Gravimetric analysis describes a set of methods in analytical chemistry for the quantitative determination of an analyte based on the mass of a solid. 2. Give the reason/s for the following a. use of ashless filter paper – This is to prevent the addition of mass to the analyte. b. addition of ammonium chloride – This is to minimize the coprecipitation of divalent cations. c. use of methyl orange – It is used as the indicator in the analysis 3.