Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

1)A student separates a 3.50 g sample of an unknown mixture of benzoic acid, 4-n

ID: 886206 • Letter: 1

Question

1)A student separates a 3.50 g sample of an unknown mixture of benzoic acid, 4-nitroaniline, and benzil using an acid-base extraction procedure. After the separation, the student finds that there is 1.08 g of benzoic acid, 0.900 g of 4-nitroaniline, and 1.62 g of benzil. Calculate the total percent recovery (include three significant figures).

2)What mistakes during the extraction procedure could lead to a percent recovery above 100%? you can pick more than one answer

a)Not all of the drying reagent was filtered out.

b)The samples were left in the oven too long.

C)The student started with too much sample.

d)The samples were not dried enough.

Explanation / Answer

Actual mixture weight is 3.50 grams

recovere weight is 1.08 + 0.9 + 1.62 = 3.6 grams

total % = 3.6 / 3.5 = 1.03 x 100 = 103 %

two possibilities might be

1 Not all of the drying reagent was filtered out.

2 The samples were not dried enough.