We’re being asked to determine the molecular weight of the unknown gas.
Recall that molecular weight is in grams per 1 mole of a substance.
First, we have to calculate the amount of gas in moles using the ideal gas equation.
P = pressure, atm
V = volume, L
n = moles, mol
R = gas constant = 0.08206 (L·atm)/(mol·K)
T = temperature, K
Isolate n (number of moles of gas):
An unknown gas contained in a 1.85 L flask is weighed and found to have a mass of 15.87 g at a pressure of 2.45 atm and a temperature of 18.6°C. What is the molecular weight of the gas?
a. 5.35 g/mol
b. 83.8 g/mol
c. 1.14 g/mol
d. 155 g/mol
e. 77.1 g/mol
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