Empirical Formulas and Molar Mass: Part 2-Mass, Atoms, Moles 1

Objectives -Be able to use atomic mass to relate grams, moles and atom number -Determine the number of atoms, moles, and grams of different substances 2

Mass, Atoms, Moles KC 4 H 5 O 6 is the empirical formula for cream of tartar How many atoms of oxygen are in 1 formula unit of cream of tartar? 6 atoms O 3

Mass, Atoms, Moles KC 4 H 5 O 6 How many atoms are in 1 formula unit of cream of tartar? 16 atoms 1 potassium 4 carbon 5 hydrogen 6 oxygen 4

Mass, Atoms, Moles KC 4 H 5 O 6 How many formula units are in 1 mole of cream of tartar? 6.02 x formula units 5

Mass, Atoms, Moles KC 4 H 5 O 6 How many atoms of oxygen are in (PER) 1 mole of cream of tartar? ? atoms O/mole KC 4 H 5 O 6 = 6 atoms O x 6.02 x10 23 formula unit KC 4 H 5 O 6 1 formula unit KC 4 H 5 O 6 1 mole KC 4 H 5 O 6 =3.61 x atoms O/mole KC 4 H 5 O 6 6

Mass, Atoms, Moles KC 4 H 5 O 6 How many moles of oxygen atoms are in 1 mole of cream of tartar? Let’s put this in perspective………. 7

How many wheels are in a dozen bicycles? 1 bicycle = 2 wheels 1 dozen bicycles = 2 dozen wheels 1 mole bicycles = 2 mole wheels 8

How many dozen hydrogen atoms are in 1 dozen water molecules? 1 water = 2 hydrogen 1 dozen water = 2 dozen hydrogen 1 mole water = 2 mole hydrogen H2OH2O 9

Mass, Atoms, Moles So……… KC 4 H 5 O 6 How many moles of oxygen atoms are in 1 mole of cream of tartar? 6 moles O 10

Mass, Atoms, Moles KC 4 H 5 O 6 What is the mass of the oxygen atoms in (PER) 1 mole of cream of tartar? ? g O/ mole KC 4 H 5 O g O x 6 moles O x = 96.0 g O 1 mole O 1 mole KC 4 H 5 O 6 mole KC 4 H 5 O 6 11

Let’s Do It!!! How many atoms in one formula unit? Magnesium Acetate: Mg(C 2 H 3 O 2 ) 2 1-Mg 4-C 6-H 4-O 15 total atoms 12

Let’s Do It!!! How many formula units in one mole of Magnesium Acetate: Mg(C 2 H 3 O 2 ) x formula units 13

Let’s Do It!!!! How many oxygen atoms are in one formula unit? Magnesium Acetate: Mg(C 2 H 3 O 2 ) 2 4 oxygen atoms 14

Let’s Do It!!! How many oxygen atoms are in one mole of this substance? Magnesium Acetate: Mg(C 2 H 3 O 2 ) 2 ? O atoms = mole Mg(C 2 H 3 O 2 ) 2 (4 O atoms) x (6.02 x units Mg(C 2 H 3 O 2 ) 2 ) = unit Mg(C 2 H 3 O 2 ) 2 mole Mg(C 2 H 3 O 2 ) 2 = 2.41 x atoms O mole Mg(C 2 H 3 O 2 ) 2 15

Let’s Do It!!! How many moles of oxygen atoms are in one mole of this substance? Magnesium Acetate: Mg(C 2 H 3 O 2 ) 2 4 moles of Oxygen 16

Let’s Do It!!! What is the mass of oxygen atoms in one mole of this substance? Magnesium Acetate: Mg(C 2 H 3 O 2 ) 2 ? g O = 1 mole Mg(C 2 H 3 O 2 ) g O x 4 moles O 1 mole O 1 mole Mg(C 2 H 3 O 2 ) 2 = 64.0 g O/ 1 mole Mg(C 2 H 3 O 2 ) 2 17

Objectives -Be able to use atomic mass to relate grams, moles and atom number -Determine the number of atoms, moles, and grams of different substances 18