Measuring the Melting Points of Compounds and Mixtures Flashcards
objective
- finding melting point of pure benzoic acid and acetanilide
- compare melting point in data table
loading a melting capillary tube
- crush compound
- tap capillary tube in the crude powder
- use tapper on digimelt
- mount capillary tube into the digimelt
melting point
solid state is in equilibrium with the liquid state
melting point range q
temperature range over which crystals first begin to liquefy up until the point at which the entire sample is in liquid form
What does the melting range show? pure or impure?
narrow range- pure
broad range- impure
sweating
shouldn’t be mistaken for melting
at the melting point of a compound what is occurring to the intermolcular forces that hold the molecules together and keep it in its solid state?
the melting point is has acquired energy to break the intermolecular forces changing it to liquid form
WHat are the two ways that melting point can be used to assess the purity of a mixture?
- the purer the material, the higher the melting point
2. the purer the material, the narrower the melting point range
How does the addition of successive amounts of an impurity affect the melting point?
melting point will decrease in proportion to the amount of impurity