A container has a volume of #7 L# and holds #2 mol# of gas. If the container is expanded such that its new volume is #15 L#, how many moles of gas must be injected into the container to maintain a constant temperature and pressure?

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Answer 1 · 2017-01-17T13:30:58

Increase the amount of gas to 4.29 mol by injecting another 2.29 mol.

We can use the ideal gas law for this, written in its proportionality form:

#(P_1V_1)/(n_1T_1) = (P_2V_2)/(n_2T_2)#

If temperature and pressure are to be held constant, #P_1=P_2# and #T_1=T_2#, so these terms can be cancelled from the equation:

#V_1/n_1 = V_2/n_2#

#(7L)/(2mol) = (15L)/n_2#

#n_2=(2(15))/7=4.29 mol#