Volumetric Analysis

Chapter 8

Solution

is a homogeneous mixture of a solute and solvent

Concentration

of a solution is the amount of solute dissolved in a given volume of the solution

%(w/w)

Stands for weight per weight. The volume of each chemical is disregarded and only the weight is used.

%(w/v)

This unit is mass per unit volume. This is used when a solid chemical is dissolved in a liquid.

%(v/v)

This stands for volume per volume. Used when both chemical in a solution are liquid

Part per Million (ppm)

This unit is very diluted solutions. Means the concentration in mg/L. This calculated by multiplying the in g/L by 1000. 1000mg =1g.

Unit for Molarity

mol/L = M

Standard solution

is one whose concentration is accurately known

Primary standard

is a substance that can be directly weighted and used to make a standard solution

Solution must have:

• Be available in a pure and stable solid state

• Be soluble in water

• Have a high molecular mass

• Be anhydrous (no water of crystallisation)

Examples of a Primary Standards Solutions

• Na₂CO₃

• NaCl

Examples of a Non-primary Standards Solutions

• HCL - It absorbs moisture from air

• I₂ - It sublimes

• H₂SO₄ -It absorbs moisture from air

• NaOH -It absorbs CO₂ & moisture from air

• KMnO₄ - It’s reduced by sunlight