what is the purpose of the test standards prepared in this experiment? the test standards are good practice for making solutions that contain different excess reactants. each test standard shows what an excess of each reagent looks like, so they are the standards against which to compare the different samples. each test standards shows how the limiting reactant is left over after the reaction, so they are the standards against which to compare other samples. each test standards shows how the excess reactant is completely consumed in the reaction, so they are the standards against which to compare other samples.