Question

There are many different primary standards that could be used in a standardization titration.

1. What are the criteria of a primary standard?

2. What are three other primary standards besides citric acid?

3. Is citric acid a greener standard than these?

    Please explain this to me, I don't understand it.

Answer 1

1) The primary standard is a solution which is used to standarized other solutions and to determine the concentration of other solutions in a titration.

to be a primary standard

a) The composition should remain constant.

b) they should not decompose with time

c) They should have high shelf life

d) they should maintain high purity for a long duration of time

e) they should not absorb moisture from environment , should not be hygroscopic

f) easily availability is also required

2) sodium chloride is a primary standard ( but should be prepared from analytical grade) , benzoic acid is also a primary standard

3) Yes citric acid a green standard as we can obtain it from natural sources , any citrus fruit like lemon.