Question #a9643
1 Answer
Explanation:
The idea here is that you need to use the vapor density of ammonia,
At this point, you need to use the definition of NTP (Normal Temperature and Pressure) and the ideal gas law equation to find the volume of the gas.
So, the vapor density of a gas is calculated by comparing the density of the gas with that of hydrogen gas,
In essence, the vapor density of a gas tells you the ratio that exists between a mass of the gas and the mass of hydrogen gas that occupies the same volume as the mass of the gas.
You can thus say that
#color(blue)(|bar(ul(color(white)(a/a)"vapor density" = "molar mass of the gas"/"molar mass of H"_2color(white)(a/a)|)))#
If you take the molar mass of hydrogen gas to be equal to
#M_ ("M NH"_ 3) = "vapor density" xx M_ ("M H"_2)#
#M_("M NH"_3) = 8.5 xx "2 g mol"^(-1) = "17 g mol"^(-1)#
Now, use the molar mass of ammonia to find how many moles you have in
#85 color(red)(cancel(color(black)("g"))) * "1 mole NH"_3/(17color(red)(cancel(color(black)("g")))) = "5 moles NH"_3#
The ideal gas law equation looks like this
#color(blue)(|bar(ul(color(white)(a/a)PV = nRTcolor(white)(a/a)|)))" "# , where
NTP conditions are defined as a pressure of
Rearrange the equation to solve for
#PV = nRT implies V = (nRT)/P#
#V_(NH_3) = (5 color(red)(cancel(color(black)("moles"))) * 0.0821(color(red)(cancel(color(black)("atm"))) * "L")/(color(red)(cancel(color(black)("mol"))) * color(red)(cancel(color(black)("K")))) * 293.15color(red)(cancel(color(black)("K"))))/(1color(red)(cancel(color(black)("atm"))))#
#V_(NH_3) = color(green)(|bar(ul(color(white)(a/a)"120 L"color(white)(a/a)|)))#
The answer is rounded to two sig figs.