__REFERENCE SECTION__: INTRODUCTION - CHEMICAL CALCULATIONS (2)
*Molar Mass* (*M*)
The molar mass (*M*) of a substance has the same numerical value as its
relative atomic or molecular mass, but has the units g mol-¹.

*Masses into Moles*
The conversion of masses into moles requires the use of this equation:
Number of moles (*n*) of substance = Mass (*m*) ÷ Molar mass (*M*)

*Moles into Masses*
The conversion of moles into masses requires the use of this equation:
Mass (*m*) of substance = Number of moles (*n*) × Molar mass (*M*)

*Concentration of a Solution*
The concentration (*C*) of a solution, expressed as mol dm-³, is the
number of moles (*n*) of solute dissolved in a volume (*V*) of one cubic
decimetre of solvent; this quantity is calculated using this equation:
Conc. (*C*) of soln. = No. of moles (*n*) of solute ÷ Vol. (*V*) of solvent

*Density of a Gas*
The density (*D*) of a gas, expressed in g cm-³, is the mass (*m*) of gas
contained in a volume (*V*) of one cubic centimetre. Because experiments
have shown that 1 mole of any gas, at room temperature and pressure
(r.t.p.), occupies a volume of 24000 cm³, the density of a gas can be
calculated using this equation:
Density (*D*) of a gas = Molar mass (*M*) ÷ 24000

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