Question

When is it appropriate to use mol units as opposed to grams ?

Answer 1

diffenent compounds may gave different weights

for example

2H2 + O2 ----------->2 H2O

H2 = 2 g

O2 = 32 g

if we assume moles

1 moles H2 = 6.023 x 10²³  molecules

1 mole O2 = 6.023 x 10²³  molecules.

so in any chemical reaction by looking reaction we can assume mole ratio of reactants rather than mass ratio

A + B ------> C

we can write directly bylooking reaction

1: 1 mole ratio of A and B

but mass ratio we cannot write by looking reaction unless we knoe molar masses.