1. Counting Atoms Chapter 9

4. MOLE??

5. Moles of Particles In one mole of a substance, there are 6 x 10 23 particles

6. Calculating the number of moles from the number of particles TB P147 1. Calculate the number of moles of particles in a.2.4 x 10 23 atoms of hydrogen, H b.4.2 x 10 24 molecules of carbon dioxide, CO 2 c.3 x 10 22 copper ions, Cu 2+ Number of moles = Number of particles 6 × 10 23

7. Calculating the number of moles from the number of particles TB P147 2. Calculate the number of particles in a.3 moles of carbon atoms, C b.0.75 moles of ammonia molecules, NH 3 c.25 moles of sodium chloride, NaCl Extension Question! How many atoms are there in 0.75 moles of ammonia molecules? Number of moles = Number of particles 6 × 10 23

8. Molar Mass The mass of one mole of any substance is called the molar mass. The molar mass is the relative atomic mass of the element in grams. For Substances Consisting of Atoms The molar mass is the relative molecular mass of the substance in grams. For Substances Consisting of Molecules The molar mass is the relative formula mass of the substance in grams. For Substances Consisting of Ions

9. Calculating the number of moles from the molar mass Number of moles = Mass (in g) Molar mass (in g) TB P150 1. (a) How many moles of atoms are contained in 32 g of oxygen atoms? 4. (c) Calculate the mass of 4 mol of oxygen molecules, O 2 ?