Nitrogen dioxide is a red-brown gas that is responsible for the color of photochemical smog. A sample of nitrogen dioxide has a volume of 28.6 L at 45.3°C and 89.9 kPa. What is its volume at STP?
A)21.8 L
B)27.6 L
C)29.6 L
D)37.6 L
E)153 L

Question

Quizplus · Accepted Answer

According to the ideal gas law,
PV = nRT
where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.
To find the volume at STP (standard temperature and pressure), we need to use the conditions:
P = 101.3 kPa
T = 273 K
R = 8.31 J/mol·K
First, we need to find the number of moles:
PV = nRT
n = PV/RT
n = (89.9 kPa)(28.6 L)/(8.31 J/mol·K)(45.3+273) K
n = 1.29 mol
Now we can use the molar volume of a gas at STP, which is 22.4 L/mol:
V = n(V/mol)
V = (1.29 mol)(22.4 L/mol)
V = 28.9 L
Since the volume at STP is less than the initial volume, the correct answer is A) 21.8 L.

Nitrogen Dioxide Is a Red-Brown Gas That Is Responsible for the Color