A student obtained 1.69 g of pure caffeine following recrystallization from a crude sample, which originally weighed 2.51 g. What is the percent recovery of pure caffeine from crude?

The recovery of pure caffeine is 67.3% of the original, crude sample.

Explanation:

Step 1: Data given

Mass of pure caffeine = 1.69 grams

Original mass of sample = 2.51 grams

Step 2: What is the percent recovery of pure caffeine from crude?

Percentage = (mass of recovery / original mass) * 100%

Percentage = (1.69 grams/2.51 grams) * 100%

Percentage = 67.3 %

The recovery of pure caffeine is 67.3% of the original, crude sample.