Okay, I have some confusion on a lab question for chemistry.

Question

The question was if you were preforming a microscale extraction of a 0.2 g of benzoic acid/fluorenone mixture (About 6 mL of dichloromethane and 2 mL of NaOH were added through out this experiment up until the final steps of heating to the evaporation of flurenone and filtration of the acid) and the recovered mass of the benzoic acid was determined to be .05 grams, what would the approximate mass recovered of the fluorenone be under normal lab conditions?

Our class has never preformed this lab before, but I know percent recovery is mass recovered divided by mass of original sample x 100. So the acid % recovery would be around 28% by that math. But the other I have no idea really. I know a % recovery of over 100% or near 100% is not possible/realistic. So would the mass recovered of the fluorenone be something around .1 g I guess since the acid mass was so small compared to the sample weight making the overall recovery 76% or is that still too low?

Answer 1

If you are looking for percent recovery benzoic acid as a percent of the original sample it is (0.05/0.2)*100 = 25% but that may not be percent recovery of the benzoic acid since you don't know how much benzoic acid was in the sample initially. If you can assume the fluorenone was the rest of it then it is 75% BUT I doubt that assumption is valid. If you have a table showing solubility benzoic acid and fluorenone in the solvents used and at the temperatures used we might be able to do a better job of estimation.