√1 mole of any substance contains 6.02 × 1023 particles of that substance. √ The mass of any substance is calculated by multiplying any subscripts in the formula by the average atomic mass, and totaling these sums for all of the elements in the formula. √ Example: 1.0 moles of CH4 would have a mass of 12.01 + 4(1.01) = 16.05g√ To find the mass of 1 molecule of CH4 you would simply divide the molar mass by the number of particles in one mole, 6.02 × 1023. √ 16.05g 1 mole × 1 mole 6.02 X 1023 molecules = 2.67 × 10-23 g/molecule

Your turn! Complete the table below in your notes, and check your answers.

 Find the molar mass of: Mass of one molecule or atom: C2H6 Interactive popup. Assistance may be required. Check Your Answer 30.08g Interactive popup. Assistance may be required. Check Your Answer 5.00 × 10-23 O2 Interactive popup. Assistance may be required. Check Your Answer 16.0g Interactive popup. Assistance may be required. Check Your Answer 2.66 × 10-23 NH3 Interactive popup. Assistance may be required. Check Your Answer 17.03g Interactive popup. Assistance may be required. Check Your Answer 2.83 × 10-23 H2O Interactive popup. Assistance may be required. Check Your Answer 18.0g Interactive popup. Assistance may be required. Check Your Answer 2.99 × 10-23