Response:
a. The return of the process fluid after it has been cooled, condensed, or heated in a distillation column or packing.
b. should remain stable at elevated temperatures
should not generate additional by-products
should be chemically inert
c. expressed as a range
d. determined by conducting a series of measurements
e. impurities cause substances to melt at lower temperatures.
Explanation:
a. In a reflux system, the condensate is returned to the initial flask or boiler. This keeps the process fluid at a constant temperature without needing more fuel while increasing the molar fraction of the distillate (which enhances product purity).
b. A solvent needs to be stable and should not participate in side reactions that produce unwanted by-products, ideally remaining inert at elevated temperatures.
c. It is advisable to report melting points as a range since various factors influence the melting point in experimental setups.
d. Melting points can be ascertained through a series of graphical measurements.
e. Impurities reduce the melting point of substances.
: To find the mass of a single washer, divide the total measured mass by the number of washers 
. Step 
: Convert kilograms to milligrams knowing 
; thus 
resulting in the final answer 
.