Question

What are primary standard substance and secondary standard substanse?

Answer 1

Primary standards have some peculiar properties:
They are nonsensitive to
atmospheric oxygen
They have known formula and molecular weight
They are
usually high molecular weight compounds
They have a constant concentration
/uniform composition for a long period of time
They are powerful
reactants

Secondary standards are:
Influenced by
atmosphere/environment
Concentration change over time
Usually powerful
reactants
Usually cheap & easy to use