Question

An open flask sitting in a lab refrigerator looks empty, but it is actually filled with a mixture of gases called air. If the flask volume is 5.00 L, and the air is at standard temperature and pressure, how many gascous molecules does the flask contain? number of gaseous molecules:

Answer 1

Given:

P = 1.0 atm

V = 5.0 L

T = 273.0 K

find number of moles using:

P * V = n*R*T

1 atm * 5 L = n * 0.08206 atm.L/mol.K * 273 K

n = 0.2232 mol

use:

number of molecules = number of mol * Avogadro’s number

number of molecules = 0.2232 * 6.022*10^23 molecules

number of molecules = 1.344*10^23 molecules

Answer: 1.34*10^23 molecules