Question

2.00 moles of a typical gas would occupy how many liters at 1 atm and 0◦c?

Answer 1

Answer:

• V  ≈ 45 liter

Explanation:

You can deal with this question using two different but related approachs.

1) First approach: 1 mole of gas at 1 atm and 0°C occupy 22.4 liter.

With that you can set a proportion:

• 1 mole / 22.4 liter = 2.00 / V

⇒ V = 2.00 mole × 22.4 liter / 1 mole = 44.8 liter.

2) Second approach: use ideal gas equation:

• pV = nRT

⇒ V = nRT / p

• V = 2.00 moles × 0.0821 atm-liter / K-mol × 273.15 K / 1 atm = 44.85 liter ≈ 44.9 liter.

There, the two calculations yield the same result, although the second one is more accurate only if you need to use 3 or more significant digits, which is not correct in this case.

If you measure the presure as 1.0 atm (two significant digits) and the temperature as 0.0 °C (two significant digits), the volume must be resported with two significant digits, which yileds to the same result with both calculations: 45 liter.