Question

Three grams of a gas at 0°C are placed in a sealed, 10-L flask and maintained at the same temperature. The molar mass of the gas is 20 g/mol. State (true or false) whether each of the following would probably occur if the valve to the flask is opened, and explain your answers.

a. The gas and air will remain separate and will not mix.

b. The gas and air will mix and the gas will react with oxygen in the air.

c. The gas will rush out of the bottle.

d. At 0°C, the three grams of gas will still occupy 10 L.

e. Air will rush into the bottle.

Answer 1

moles of gas = mass/molar mass= 3/20=0.15 moles, T= 0 deg.c= 0+273=273K, V= 10L

R= gas constant =0.0821L.atm/mole.K, P= pressure of gas= nRT/V= 0.15*0.0821*273/10=0.34 atm

when the gas is opened, since the pressure inside the gas is less than the atmopspheric pressure, since flow takes place from high pressure to low pressure, air rushes into the bottle.

statement 1 is false since the concentration of air in the flask is less and more in the atmosphere, where as the concentration of gas in the gas in the air is less while in the flask it is more, both gases mix

statement 2 is false, since it is not known what is the gas

statement 3 is also false since the preessure in the flask is less, air will rush from atmosphere into the flask

True since the air from atmosphere leaks from air into the flask, the gas remains at 3 gm and 0 deg.c and 10L.