A tank containing liquid butane and one containing liquid propaneare sitting adjacent to one another. Each tank is equipped with a regulator with a pressure gauge. Classify these statements as true or false.

(a) The pressure reading for the butane tank is higher than that for the propane tank.

(b) The pressure readings will change when more liquid is added tothe tanks.

(c) If the tanks are placed outside and the sun warms each tank to 46C, the pressure readings will be higher than theywere initially.

(d) If an equal number of moles of gas is allowed to escape rapidly from each tank, the temperature of the butane tank will be lower than that of the propane tank.

a). False

b). False

c). True

d). True

Explanation:

a). False

Because liquid propane is more volatile than liquid butane, since the molar mass of propane is less than that of butane. Therefore, The pressure reading for the propane tank will be higher than that of butane.

b). False

Because the vapour pressure of a liquid does not depend on mass, therefore the pressure will not change when more liquid is added to the tanks. It is an intensive property.

c). True

According to Gay Lussac's law, when volume remaining constant, the pressure increases with increase in temperature. Thus vapour pressure increases when the tank is placed outside as temperature ins increased.

d). True

Since liquid butane is less volatile than liquid propane, therefore more heat will be required to vapourised to liquid butane. Thus when same number of gas is escaped rapidly from the tanks, the temperature will be lower in the butane tank than the temperature of the propane tank.