What is the volume in liters occupied by 10.0 grams of CO2 gas at STP? (Hint: you must first find the molecular mass of CO2.)  

1 Answer

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thilina-g | College Teacher | (Level 1) Educator

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Molar mass of CO2  = 44 g per mol

The mass of CO2 available = 10 g

Therefore, the number of CO2 moles present can be calculated as,

Number of moles of CO2= mass / molar mass

Number of moles of CO2= 10 g/ 44 g per mol

                                   = 5/22 mol

                                   = 0.227 mol.

Defintion of STP - Standard Temperature & Pressure

This is 0 C and 1 bar according to IUPAC definition. At these conditions, the volume of 1 mol of ideal gas is 22.71 L/mol. We have to assume that CO2 behaves ideally.

Volume of 1 mol of an ideal gas at STP is 22.71 L/mol. But according to Avogadro Law,  volume, V is,

V = kn   Where k is constant and n is the number of moles.

If the volume of 10 g of CO2 is V1, then,

22.71 = k x 1 (for 1 mol of ideal gas)

V1 = k x (5/22)  (since CO2 sample has only 5/22 moles)

V1 = 22.71 x (5/22) = 5.16 L


Therefore, volume of 10 g of the CO2 is 5.16 L.