The molar mass of a substance is found by adding the atomic masses of the elements in one mole of that substance, expressed in grams per mole (g/mol). To find the molar mass, follow these steps:

1. Identify each element in the substance's chemical formula.
2. Find the atomic mass of each element from the periodic table (in g/mol).
3. Multiply the atomic mass of each element by the number of atoms of that element in the formula.
4. Add the values from step 3 for all elements to get the total molar mass.

For example, for water (H2O):

• Hydrogen (H) has an atomic mass of approximately 1.01 g/mol; there are 2 hydrogen atoms.
• Oxygen (O) has an atomic mass of approximately 16.00 g/mol; there is 1 oxygen atom.
  Molar mass = (2 × 1.01) + (1 × 16.00) = 18.02 g/mol.

This approach works for elements and compounds, including those with parentheses, where you multiply subscripts outside the parentheses by those inside (like (NH4)2SO4). All molar masses are reported in grams per mole (g/mol).