How many moles of CO_2CO2 (g) are in a 5.6 L sample of CO_2CO2 measured at STP?

1 Answer
Jan 30, 2016

"moles"=0.25moles=0.25

Explanation:

Using the ideal gas equation, we can solve for the number of moles:

PV=nRTPV=nRT

where:
P=P=pressure
V=V=volume
n=n=moles
R=R=universal constant (8.314(kPa*L)/(mol*K))(8.314kPaLmolK)
T=T=temperature (Kelvin)

Recall that at STP conditions:

P=101.325P=101.325 kPakPa
T=273.15T=273.15 KK

To solve for the number of moles of carbon dioxide gas, substitute your known values into the ideal gas equation:

PV=nRTPV=nRT

n=(PV)/(RT)n=PVRT

n=((101.325kPa)(5.6L))/((8.314(kPa*L)/(mol*K))(273.15K))n=(101.325kPa)(5.6L)(8.314kPaLmolK)(273.15K)

n=((101.325color(red)cancelcolor(black)(kPa))(5.6color(orange)cancelcolor(black)(L)))/((8.314(color(red)cancelcolor(black)(kPa)*color(orange)cancelcolor(black)(L))/(mol*color(green)cancelcolor(black)(K)))(273.15color(green)cancelcolor(black)(K)))

n=0.2498580892 mol

n=0.25 mol (rounded to 2 significant figures)

:., there are 0.25 mol in 5.6 L of CO_(2(g)) at STP conditions.