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 4.00 L, and the air is at standard temperature and pressure, how many gaseous molecules does the flask contain

Answer 1

Answer:
`1.07* 10^(23)` molecules

Step-by-step explanation:

According to the ideal gas equation:

PV=nRT

P = Pressure of the gas = 1 atm ( at STP)

V= Volume of the gas = 4.00 L

T= Temperature of the gas in kelvin = 273 K ( at STP)

R= Gas constant = 0.0821Latm/kmol

n= moles of gas= ?

Putting in the values we get:

`1atm* 4.00L=n* 0.0821Latm/Kmol* 273K`

`n=0.178mol`

Now 1 mole of any substance contains
`6.023* 10^(23)` molecules at STP

Thus 0.178 mole of any substance contains =
`(6.023* 10^(23))/(1)* 0.178=1.07* 10^(23)` molecules at STP

Thus there are
`1.07* 10^(23)` gaseous molecules in the flask.