Question

A compound is heated to produce a gas whose molecular weight is to be determined. The gas is collected by displacing water in a water-filled flask inverted in a trough of water. Which of the following is necessary to calculate the molecular weight of the gas, but does NOT need to be measured during the experiment?

A). Mass of the compound used in the experiment
B). Temperature of the water in the trough
C). Vapor pressure of the water
D). Barometric pressure
E). Volume of water displaced from the flask

Answer 1

To calculate the molecular weight of the gas, you need to know the mass of the compound, temperature of the water, barometric pressure, and volume of water displaced. The vapor pressure of the water does not need to be measured.

Step-by-step explanation:

In order to calculate the molecular weight of the gas, you need to know the mass of the compound used in the experiment, the temperature of the water in the trough, the barometric pressure, and the volume of water displaced from the flask. However, the vapor pressure of the water does not need to be measured during the experiment to calculate the molecular weight of the gas.