Question

empirical formula for
Ca 40.078 22.3%
As 74.9216 41.6%
O 15.9994 35.6%
H 1.00794 0.560%

Answer 1

The empirical formula : CaAsO₄H

Further explanation  

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

• Determine the mass ratio of the constituent elements of the compound.  
• Determine the mole ratio by by dividing the percentage by the atomic mass

• Ca

$\tt \dfrac{22.3}{40.078}=0.556$

• As

$\tt \dfrac{41.6}{74.9246}=0.555$

• O

$\tt \dfrac{35.6}{15.9994}=2.225$

• H

$\tt \dfrac{0.56}{1.00794}=0.556$

Divide by the smallest ratio(0.555) :

Ca : As : O : H ⇒

$\tt \dfrac{0.556}{0.555}\div \dfrac{0.555}{0.555}\div \dfrac{2.225}{0.555}\div \dfrac{0.556}{0.555}=1\div 1\div 4\div 1$