A. What is a “mole”? 1) 6.022 x 1023 of ANYTHING is a mole 2) A mole is like a “dozen” 3) One dozen donuts = 12 donuts One mole of donuts = 6.02x1023 donuts 4) One dozen cars = 12 cars One mole of cars = 6.02x1023 cars

A. What is a “mole”? 5) The atomic mass on the periodic table equals the mass of one mole (6.02 x 1023) of atoms of that element—this is called the “molar mass” of the element. Ex: One atom of Si is 28.1 amu. One mole of Si is 28.1 grams 6) The mole of any compound is the sum of each atom’s molar mass. One molecule of CO is 12.0 + 16.0 = 28.0 amu One mole of CO is 12.0 + 16.0 = 28.0 grams

B.What does a formula tell us? H2O Tells us the number of atoms in the molecule: 1 molecule of H2O is made up of 2 atoms of hydrogen and 1 atom of oxygen Also tells us the number of moles of atoms in a mole of molecules: 1 mole of H2O is made up of 2 moles of hydrogen and 1 mole of oxygen

C. Why do we need the mole? Atoms and molecules are VERY SMALL. Atoms and molecules are TOO SMALL TO COUNT. We ARE able to weigh things in the lab. So, instead of COUNTING atoms or molecules we WEIGH them.

D. Count out 50 blocks of Lucite. How many grams do you think this is? _______________ molecules? ______________________________ atoms? _______________________________ Place your sample along with other classmate samples in the large beaker.

The formula for Lucite is C5H8O2. Calculate the molar mass: Calculate how many blocks in the class sample: _____________________________ Mass of class sample ____________

How many molecules in the entire sample?

How many molecules in each Lucite block?