Counting Atoms in Formulas Practice

3H2O The coefficient tells you the number of molecules. H2O + H2O + H2O The subscript tells you how many atoms of that element in each molecule.

2H2O 1 Add your 1s 2 Molecules = H = O = Total = 4 2 6

H2O 1 1 Add your 1s 1 Molecules = H = O = Total = 2 1 3

4CO2 Add your 1s 1 4 Molecules = C = O = Total = 4 8 12

H2O2 1 1 Molecule = H = O = Total = 2 2 4

C6H12O6 1 1 Molecule = C = H = O = Total = 6 12 6 24

NH3 1 1 1 Molecule = N = H = Total = 1 3 4

2N2 2 Molecules = N = Total = 4 4

CH4 1 1 1 Molecules = C = H = Total = 1 4 5

2HCl 1 1 2 Molecule = H = Cl = Total = 2 2 4

3CaCO3 1 1 3 Molecules = Ca = C = O = Total = 3 3 9 15