Question

Determine the number of moles of oxygen atoms in each of the following.

4.37 mol H2O2

2.30 mol N2O

2.26×10⁻² mol H2CO3

Answer 1

We calculate number of moles oxygen by using mol ratio between given compounds. Once we get moles of O then we can get its number of atoms by using Avogadro’s number.

H2O2 :

Mol ratio between H2O2 : O   is 1:2

Number of moles of O2 = 4.37 mol H2O2 x 2 mol O / 1 mol H2O2 = 8.74 mol O

Number of O atoms = 8.74 mol O x 6.02E23 O atoms/mol O= 5.26 E 23 atoms

N2O ; Here mol ratio between N : O is 1 : 1

Therefor number of moles of O = Number of moles of N2O = 2.30 mol O

Number of O atoms = 2.30 x 6.02 E23 O atom

= 1.38 E24 O atoms.

Mol H2CO3 : mol O is 1 : 3

Number of moles of O = 2.26 E-2 mol H2CO3 x 3 mol O/ 1 mol H2CO3

= 6.78 E-2 mol O

Number of O atom = 6.78 E-2 x 6.02E23 O atoms / 1 mol O

= 4.08 E22 O atoms