Mercury diffusion pumps may be used in the laboratory to produce a high vacuum
CHEMISTRY · Subjective · A Level · Chemistry · Amount of substance · Amount of substance
Problem
Mercury diffusion pumps may be used in the laboratory to produce a high vacuum. Cold traps are generally placed between the pump and the system to be evacuated. These cause condensation of mercury vapours and prevent mercury from diffusing back into the system. The minimum pressure of mercury that can exist in the system is the vapour pressure of mercury at the temperature of cold trap. Calculate the number of mercury atom per unit volume in a cold trap at −120∘C . The vapour pressure of mercury at this temperature is 10−16 torr.