Answer: 78.125%
Step-by-step explanation:
From the question, we are informed that a student obtained 2.00g of pure caffeine following recrystallization from a crude sample, which originally weighed 2.56g.
The percent recovery of pure caffeine from crude will be calculated as:
= Mass of pure caffeine / Mass of crude sample × 100
= 2.00 / 2.56 × 100
= 78.125%