Matter 1.1 & 1.2

MOLARITY, M
⚫The number of moles of solute per cubic
decimetre (dm3) or litre (L) of solution.

molarity, M = moles of solute (mol)
volume of solution (dm3 )

Unit : mol dm-3 or mol L-1 or Molar(M)

Note: 51
1 dm3 = 1000 cm3
1 L = 1000 mL

MATTER

B.MOMLoAlLaITliYty, m(m)

⚫Molality is the number of moles of solute dissolved
in 1 kg of solvent

molality, m = moles of solute (mol)
mass of solvent (kg)

Unit : mol kg-1 or molal or m

MATTER 52

MOLE FRACTION (X)

⚫Mole fraction is the ratio of the number of moles of
one component to the total number of moles of all
component present.

Mole fraction (X)
mole of solute

=
mole of solute + mole of solvent

No unit
Mole % = mole fraction x 100
Total mole fraction = XA + XB + XC = 1

PERCENTAGE BY MASS (MASS %)

Sometimes written as % (w/w)
Percentage by mass is defined as the
percentage of the mass of solute per mass of
solution.

Mass % = mass of solute x 100

mass of solution

Mass = mass + mass
Solution solute solvent

PERCENTAGE BY VOLUME (VOLUME %)

Defined as the percentage of volume of solute
in milliliter per volume of solution in
milliliter.

volume of solute x 100
Volume % =
volume of solution

Common symbol: % (v/v) 55
Most often used for liquids and gas

MATTER