Question

What is the simplest formula for a compound containing 0.50 mol na, 0.50 mol s, and 0.75 mol o?

Answer 1

We need to get the mole ratio between the elements. To do this, we will divide by the the smallest number of moles given as follows:
0.5 mole of Na / 0.5 = 1
0.5 mole of S / 0.5 = 1
0.75 mole of O / 0.5 = 3/2

Now, we need to get rid of the fractions. To do this, we will multiply all the ratios by 2:
Na = 1 x 2 = 2
S = 1 x 2 = 2
O = 3/2 x 2 = 3

So, in the simplest formula, the ratio Na:S:O is 2:2:3
This can be written as: Na2S2O3 which is known as sodium thiosulphate.