Question

What is the empirical formula for a compound containing 28% nitrogen and 72% oxygen?

Answer 1

Answer:

Explanation:

Say you have 72 grams of oxygen   and  28 grams of nitrogen

72 grams of oxygen is    72g / 16 g/mole = 4.5 moles of oxygen

28 grams of nitrogen is   28 g / 14 g/mole = 2 moles of nitrogen

So your formula starts to look like    N2 O4.5    

    but you can't have fractions in the formula ....so multiply both of the subscripts by 2   to get

   N4 O9           Done.