CHEM 238 FINAL PAPER SOLVED QUESTIONS WITH FULL PRACTICE SOLUTION

CHEM 238 FINAL PAPER SOLVED
QUESTIONS WITH FULL PRACTICE
SOLUTION

●● What do the colors in NFPA represent?
Answer: - (top) red= flammability
- (left) blue= health
- (right) yellow= reactivity
- (bottom) white- special hazards


●● What is an SDS?
Answer: A detailed document that provides safety, handling, storage, and
hazard information for a chemical.


●● What does a rotovap do?
Answer: removes excess organic solvent


●● What do you use to remove traces of water
Answer: magnesium sulfate


●● How do you know when you have used enough magnesium sulfate
Answer: However much you need to get the snow globe effect.

, ●● What is the snowglobe effect? (2)
Answer: - the magnesium sulfate stops sticking together and starts
swirling freely like "snow."
- aka flocculation


●● How do you measure liquid reagents
Answer: graduated cylinder


●● How do you measure dry reagents
Answer: weigh boat on a scale.


●● Which is more polar: benzoic acid or a nonpolar compound
Answer: benzoic acid (carboxyl group)


●● Does benzoic acid have a higher or lower Rf value than a nonpolar
compound?
Answer: polar (benzoic acid)= lower rf value


●● What is the purpose of vacuum filtration
Answer: to separate precipitate (solid) from a solution (liquid)


●● Purest compound melting point?