A compound containing sodium, chlorine, and oxygen is 25.42% sodium by mass. A 3.25 g sample gives 4.33×1022 atoms of oxygen. What is the empirical formula?
step one calculate the % of oxygen from avogadro constant 1moles = 6.02 x 10 ^23 atoms what about 4.33 x10^22 atoms = ( 4.33 x 10^ 22 x 1 mole ) / 6.02 10^23= 0.0719 moles mass= 0.0719 x16= 1.1504 g % composition is therefore= ( 1.1504/3.25) x100 = 35.40% step two calculate the % composition of chrorine 100- (25.42 + 35.40)=39.18%
step 3 calculate the moles of each element that is Na = 25.42 /23=1.1052 moles Cl= 39.18 /35.5=1.1037moles O= 35.40/16= 2.2125 moles step 4 find the mole ratio by dividing each mole by 1.1037 moles that is Na = 1.1052/1.1037=1.001 Cl= 1.1037/1.1037= 1 0=2.2125 = 2 therefore the empirical formula= NaClO2
