Moles of Compounds

A properly written compound shows the ratio of atoms in the compound. For example, sodium carbonate (Na2CO3) shows that for every 1 compound there are 2 atoms of Na, 1 atom of C, and 3 atoms of O.

This also works with the mole. For 1 mole of the compound, there are 2 moles of Na, 1 mole of C, and 3 moles of O. This information allows us to calculate the molar mass of the entire compound, often called the formula mass.

2 mols Na 22.9897 g = 45.9794 g Na

1 mol

1 mol C 12.0107 g = 12.0107 g C

1 mol

3 mols O 15.9994 g= 47.9982 g O

1 mol

The total molar mass of Na2CO3 is 105.9883 g.

Once it is known that 1 mol of Na2CO3 = 105.9883 g, conversion factors can be made of this information:

These conversion factors can then be used in other calculations.

105.9883 g Na2CO3or

1 mol

1 mol 105.9883 g Na2CO3

What is the molar mass for potassium oxide (K2O)?

What is the molar mass for potassium oxide (K2O)?

2 mols K =

1 mol O =

What is the molar mass for potassium oxide (K2O)?

2 mols K 39.0983 g =

1 mol

1 mol O 15.9994 g =

1 mol

What is the molar mass for potassium oxide (K2O)?

2 mols K 39.0983 g = 78.1966 g K

1 mol

1 mol O 15.9994 g = 15.9994 g O

1 mol

What is the molar mass for potassium oxide (K2O)?

K2O = 78.1966 g + 15.9994 g = 94.1960 g

2 mols K 39.0983 g = 78.1966 g K

1 mol

1 mol O 15.9994 g = 15.9994 g O

1 mol

If you have 560 grams of K2O, how many moles do you have?

If you have 560 grams of K2O, how many moles do you have?

560.0 g K2O =

If you have 560 grams of K2O, how many moles do you have?

560.0 g K2O 1 mol =

94.196 g

If you have 560 grams of K2O, how many moles do you have?

560 g K2O 1 mol = 5.945 mol K2O94.1960 g

If you have 3.4 moles of K2O, how many grams do you have?

If you have 3.4 moles of K2O, how many grams do you have?

3.4 mols K2O =

If you have 3.4 moles of K2O, how many grams do you have?

3.4 mols K2O 94.1960 g =

1 mol

If you have 3.4 moles of K2O, how many grams do you have?

3.4 mols K2O 94.1960 g = 320 g K2O1 mol