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 gaseous molecules does the flask contain?

Answer 1

Answer:

There are 1.34x10²³ molecules in the flask.

Explanation:

The flask volume is 5.00 L and the air is at standard temperature and pressure.

We must use the Ideal Gas Law to solve this.

Standard temperature and Pressure are 273.15 K and 1 atm.

P . V = n . R . T

1 atm . 5 L = n . 0.082 L.atm/mol.K . 273.15K

(1atm . 5L) / (0.082 mol.K/L.atm .273.15K) = n

0.223 mol = n

This is the quantity of air in the flask. You should know by Avogadro that 1 mol has 6.02x10²³ molecules so, let's make the rule of three:

1 mol ____ 6.02x10²³ molecules

0.223 moles ______ (0.223 . 6.02x10²³) = 1.34x10²³ molecules