Transcript Units of Concentration

Units of Concentration
The analytical
chemist’s
nightmare!
SI Units
Concentration Units
Prefixes
Calculations

The Mole Concept
 The
amount of substance which
contains as many entities as there are
atoms in 12 grams of 12C.

One Mole = 6.023 x 1023

Avogadro’s Number
Calculations

Molar Solutions
 xM
= mass/RMM in 1000ml
Calculations

Molar Solutions to gdm-3
 mass
= xM x RMM in 1000ml
Calculations

Molar Solutions to ppm
 1ppm
= 1mg per kg
 mass
= xM x RMM in 1000ml
 mass
(g) x 1000 = mass (mg)
Calculations

Percentage Concentrations
Mass of Solute
%(w/w) =
x 100
Total Mass of Solution
Volume of Solute
%(v/v) =
x 100
Total Volume of Solution
%(w/v) =
Mass of Solute
x 100
100ml of Solution
Calculations

10% Ethanol in Water
10% (w/v) = 10g per 100ml = 100g in 1000ml
 100g / 46.07 = 2.17M

10% (v/v) =10ml per 100ml = 100ml in 1000ml
 100ml x 0.79 = 79g
79g / 46.07 = 1.71M

10% (w/w) = 10g per 100g = 100g in 1000g
 100g / 0.79 = 126.6ml 126.6 + 900 = 1026.6ml
 100 x 1000/1026.6 = 97.4g
97.4g / 47.06 = 2.11M

Calculations

%Concentration to Molarity
 1%
(w/v) = 1g per 100ml = 10g in 1000ml
 xM
= mass/RMM in 1000ml
Calculations

Titrations
 MAVA =
MBVB