# A compound is found to consist of 63% manganese and 37% oxygen by mass. What is the empirical formula?

Jul 11, 2017

$M n {O}_{2}$
Procedure:
% per 100wt => gms per 100 wt => moles => mole ratio => normalize (divide by smaller mole value) => adjust fraction* => Empirical Ratio => Empirical Formula

#### Explanation:

%Mn = 63% => 63gms = 63g/(55g/mole) = 1.15 mole Mn
%Oxy = 37% => 37gms = 37g/(16g/mole) = 2.31 mole Oxy

Mn:Oxy => $\left(1.15 : 2.31\right)$ => $\frac{1.15}{1.15}$:$\frac{2.31}{1.15}$ => 1:2 Empirical Ratio

=> Empirical Formula => $M n {O}_{2}$

__
* If normalized ratio is in fractions of 0.25 or 0.75 adjust by multiplying by 4, or if fraction is 0.50, multiply by 2 => smallest whole number ratio => Empirical Ratio => Empirical Formula.