If a jar of honey sits for a long time, sugar may crystallize in the jar. describe two possible cause for this crystallization?

Temperature and humidity

Explanation:

Crystallization occurs in super saturated solution. These are the solutions that have solute to solvent ratio of 2:1 or more. Typical honey is 70% sugar and 20% water (the solute concentration is too high).  

Two things cause honey to crystallize.

If temperature is lowered the rate of crystallization increases. This is because at low temperature the molecules of solvent come closer and the space between them reduces. This causes the additional solute molecules to be pushed up to form crystals.  

Secondly, humidity also plays a key role. If the humidity reduces, the water molecules evaporates from honey into air. This increases the relative concentration of the solute inside the honey, which causes the honey to crystallize.  

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.