Question

Why NaOH is not a primary standard.

Answer 1

a primary standard is insoluble solid compound that is very clear, with a consistent formula that does not change on exposure to the atmosphere and has a relatively high molar mass.

in order to be suitable for use as a primary standard:

1) a compound must first be readily available and inexpensive.

2) be very pure

3) have a known formula

4)be an unaltered in air during weighing, that is, the compound must not

a) absorb moisture from the air.

b) absorb carbon dioxide from the air

c) be oxidized by air

d) have a relatively large molar mass to minimise errors during weighing.

$NaOH$ is not suitable for use as a primary standard because they readily absorb moisture, $H_{2}O$, from the atmosphere. They readily absorb carbon dioxide from the atmosphere.