You have 100 mL of a solution of benzoic acid in water; the amount of benzoic acid in the solution is estimated to be 0.30 g. The distribution coefficient of benzoic acid in diethyl ether and water is approxi- mately 10. Calculate the amount of ben- zoic acid that would be left in the water solution after four 20-mL extractions with ether. Do the same calculation using one 80-mL extraction with ether to determine which method is more efficient.

The extraction with four 20-mL extractions with ether is more efficient.

Explanation:

We are given the following parameters which are going to help in solving this particular Question.

=> The volume of the solution of benzoic acid in water = 100mL, the estimated amount of benzoic acid in the solution = 0.30 g and the distribution coefficient (approximately ) = 10 = 1/ 10 = 0.1

Therefore, the amount of acid that would be left in the water solution after four 20-mL extractions with ether = 0.3( 0.1 × 100 ÷ 10 + 20)^4 = 0.0037 g.

Also, the amount of acid that would be left in the water solution after one 80-mL extractions with ether = 0.3( 0.1 × 100/ 10 + 80)^1 = 0.033 g.

Since 0.033 g > 0.0037 g, the extraction with four 20-mL extractions with ether is more efficient.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.