Question

An oxide of arsenic contains 3.26 g of arsenic and 1.04 g of oxygen. What is the empirical formula for this oxide?

Answer 1

The empirical formula for this oxide : As₂O₃

Further explanation:

Given

mass of Arsenic=3.26 g

mass of Oxygen = 1.04 g

Required

The empirical formula

Analysis

• find mole of elements
• determine the ratio of each element

Solution

mol of Arsenic(MW=74,9216 u) :

$\tt mol=\dfrac{3.26}{74,9216}=0.0435$

mol of Oxygen(MW=15.999 u) :

$\tt mol=\dfrac{1.04}{15.999}=0.065$.

The ratio for each element (divide by smaller mol⇒Arsenic)

Arsenic : Oxygen :

$\tt \dfrac{0.0435}{0.0435}\div \dfrac{0.065}{0.0435}=1\div 1.5\rightarrow 2\div 3$

The empirical formula : As₂O₃