Dissolved silica in river water can be determined by the formation of a green-yellow silicmolybdate complex and the comparison of its absorbance against a reference standard. In such an analysis, 50.0mLs of river water is treated by adding 1.0mL of concentrated hydrochloric acid, 2.0mLs of ammonium molybdate solution, and 1.5mLs of oxalic acid solution. After 2 minutes, the solution gave an absorbance of 0.366 measured at 410nm. When a silica standard containing 0.80mg/L was treated in the same manner, it gave an absorbance reading of 0.279 measured at the same wavelength.
A) Calculate the silica concentration in the river water in mg/L. Assume that Beer-Lambert Law holds exactly for this determination.
B) What would have been the absorbance reading of the river water sample if the standard solution had been added to it?