Question

Be specific when answering the questions, Do NOT state that "it will be affected” or that “it will be higher OR lower" 1. A couple of drops of water were accidentally placed on the folded filter paper and the mass was obtained before filtration. However, after air-drying for a week, the filter paper and precipitate were dry and the mass was obtained. As a result of this sloppy technique, how will the calculated mass of the limiting reactant be affected? 2. Due to an error in ordering lab supplies, a filter paper with a larger pore size was used and some of the precipitate passed through the filter paper. How will the calculated percent of the limiting reactant in the salt mixture be affected? 3. In a hurry to complete the experiment, Anna withdrew some liquid (and quite possibly some solid) from the reaction mixture before the filtration to determine the limiting reactant. As a result, what dilemma might she have encountered in testing for the limiting reactant?

Answer 1

1) After air drying the precipitate in the filter paper when the mass of the filter paper plus precipitate is obtained then the mass of the water drops were not obtained. So the calculated mass of the precipitate will be lower than the actual mass.

2) When some of the precipitates passed through the filter paper then the amount of precipitate that we will observe will be lesser than actual so the percentage of reactant in the limiting salt mixture will be observed to the lower than the actual percentage.

3) When Anna drew some liquid with some solids from the reaction mixture to determine the limiting reactant the percentage composition of the reactant will be unaffected as the reaction mixture is homogeneous so there should be a fixed composition of reactants and products present in the reaction mixture and she will observe that fixed percentage composition only. So the percentage of limiting reactant in the reaction mixture will not be affected.