At constant temperature and volume, a #0.2*mol# quantity of helium gas exerts a pressure of #22.7*kPa#. HALF this molar quantity of oxygen gas is injected, what is #P_"Total"#?

#A.# #34.05*kPa;#
#B.# #69.10*kPa;#
#C.# #25.05*kPa;#
#D.# #"Impossible to determine."#

1 Answer
May 29, 2017

Answer:

#"Option A"#

Explanation:

#"Dalton's Law of Partial Pressures"# states that in a gaseous mixture, the partial pressure, #P_1#, exerted by a gaseous component is the same as the pressure it would exert if it ALONE occupied the container. The total pressure, #P_"Total"#, is the sum of the individual partial pressures:

#P_"Total"=P_1+P_2+.............P_n#

Here, #0.2*mol# quantity of helium gas exerts a #22.7*kPa# pressure, so if we inject a #0.1*mol# quantity of dioxygen gas it will exert a proportional pressure, i.e. proportional to its molar quantity, a pressure of #11.35*kPa#. #P_"Total"=(22.7+11.35)*kPa=A#, as required.....

Happy?

Why doesn't the helium gas react with the dioxygen gas? Dioxygen gas is fiercely reactive.