Titration - The Basics

Titration is the quantitative analysis technique of determining the concentration of an unknown acid or base. 

Standard Solutions

PRIMARY STANDARD 

A primary standard for acids are either anhydrous sodium carbonate (Na2CO3) or sodium hydrogen carbonate (NaHCO3) and for bases, potassium hydrogen phthalate (C8H5KO4).

Primary standards MUST be:

• Pure 

• Unaffected by the environment (does not absorb moisture and does not react with the air)

• easily weighed out - that is, have a high molecular weight

They are used to confirm the concentration of the known solution (called our Secondary Standard). The secondary standard needs to be confirmed because it is often impure and affected by the environment. Therefore, we need to quantitatively confirm that the concentration we thought we created is chemically correct (you'll find that you will often be a few decimals below the exacted concentration which can have huge impacts on the maths of your titration).

SECONDARY STANDARD

This is the acid or base of known concentration that we will use to neutralise the unknown. 

Sodium hydroxide needs to be standardised against a primary standard because it contains impurities such as sodium chloride, sodium carbonate and sodium sulphate, and it readily absorbs moisture from the atmosphere. 

The standard solution goes in the burette. 

THE UNKNOWN

A solution of an acid or base with known volume but unknown concentration. 

The unknown solution goes in the conical flask.