Question

Johnny is very careless in the lab. He purified two white solids (A and B) by re-crystallization, but forgot to label the vials. Both A and B have a melting point range of 10² - 10⁴ °C, so he is not sure which solid is which. He has a small amount of an authentic sample of pure A available in the lab. What should he do?

Answer 1

The solution are in the explanation below

Step-by-step explanation:

- Find the melting point of authentic sample of pure A.

- Mix sample A into both vials.

- Use melting point depression

- Lower melting component will liquefy first, and melting point will lower/broaden the range. (Determine which vial holds sample B mixed with A)

- Vial with the same sample A melting point range would remain consistent to 102-104˚C.