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CH3041
STANDARDISATION
Secondary standard: a liquid
or solid reagent is weighed out and made up in solution,
this must then be titrated against
a primary standard solution to ascertain the precise concentration of the 2o standard.
a primary standard solution to ascertain the precise concentration of the 2o standard.
• eg. NaOH is
contaminated with Na2CO3 from reaction with atmospheric water (which
contains small amounts of carbonic acid).
contains small amounts of carbonic acid).
Standardised NaOH must be made as a secondary
standard and then standardised using potassium hydrogen phthalate as the primary
standard.
