Melting Point Range
For what two purposes are melting points routinely used?
What two effects do impurities have on the melting-point range of an organic compound?
Mixed Melting Point Techniques
-Determine the MP of the unknown and then compare it to the known table of MPs.
-Make a 50:50 mixture of the unknown and possible known.
If MP of unknown+ known= MP of known, then unknown=known
If MP of unknown + known not equal to MP of known, then unknown is not equal to known.
Rate of heating in melt-temps should be 1-2 degrees Celsius per min.
Three different organic solids A, B, C have the same melting point-->149-150C. A 50:50 mixture of A+B melts 130-139C. A mixture of A+C melts 149-150C.
What is the purpose of the boiling chips in a distillation?
Why is it dangerous to heat a liquid in a distillation apparatus that is closed and tightly at every joint and has no vent to the atmosphere?
Why is it important that the cooling water in the condenser enter from the lower end and exit at the upper and not vice-versa?
Which procedure was more efficient in separating the mixture into its component?
Why should a distillation flask not be filled much more than half-full?
Why is it important to perform a fractional distillation slowly? What happens if fractional distillation is done too quickly by rapidly raising the temperature of the heat source?
Why was the boiling point of the distillate less than 100C?
Why was the distillate cloudy throughout most of the distillation?
What properties are desireable in a recrystallization solvent?
What is the purpose of adding charcoal (activated Carbon) to the hot mixture during recrystallization?
What is the purpose of the washing the recrystallization material with fresh solvent?
Why is the wash solvent in previous question cold, not warm or hot?
What was the purpose of adding 10% NaOH solution to the ether solution in the separatory funnel in part A of the experiment?