CHAP. 2: STATE BEHAVIOUR [CONTENTS] 43
2.1 Major terms, quantities and symbols
2.1.1 Molar volumeVmand amount-of-substance (or amount) densityc
Definition
Vm=V /n , c= 1/Vm. (2.1)U Main unit: m^3 mol−^1 for molar volume, and mol m−^3 for amount density.
Example
A system containing 10 moles of nitrogen occupies a volume of 5 dm^3. Calculate the molar volume
of nitrogen and its amount density.Solution
According to (2.1), the molar volume of nitrogen is 5 × 10 −^3 /10 = 5× 10 −^4 m^3 mol−^1 , its amount
density is 2 × 103 mol m−^3.2.1.2 Specific volumevand densityρ
Definition
v=V /m , ρ= 1/v , (2.2)
whereV is the volume of a system andmis its mass.
U Main unit: m^3 kg−^1 for specific volume, kg m−^3 for density.
Example
A system containing 500 g of carbon monoxide occupies a volume of 5 dm^3. Calculate the specific
volume and density of carbon monoxide.Solution
According to formula (2.2),v= 5× 10 −^3 / 0 .5 = 10−^2 m^3 kg−^1 , andρ= 1/v= 100kg m−^3.