# The Mole - HONORS CHEMISTRY The Mole Unit 7: Stoichiometry Part I Mrs. Callender Lesson Essential Questions What is a mole? What is a mole used for? Atoms are really, really small We can not work with individual atoms or AMUs in the lab. Atomic Mass Unit WHY

Because we ? cant see things that small! We as scientists work with portions of matter large enough for us to SEE and MASS on a balance using units of GRA Click icon to

add picture Copper (II) Sulfate This presents a problem.. A pile of atoms So how large enough would we for us to see keep track contains ofbillions

that of atoms. many atoms? Chemists came up with a new unit. e h T M E L O Equivalents or Conversion Factors

1 dozen eggs = 12 eggs 1 ream of paper = 500 pieces of paper 1 rooster = two legs Equivalents or Conversion Factors 1 mole = 6.02 x 1023 There are EXACTLY 12 grams of Carbon-12 in 1 mole of Carbon-12. I did not discover the number. It was just named after me.

Avogadros Number 6.02 x 10 Named in honor of Amadeo Avogadro. 1776 - 1856 23 He studied gases and discovered that no matter what the gas, there were the same number of molecules present. Units for Avogadros Number

For instance: 1 mole = 6.02 x 1023 (many different units) 1 mole of pennies = 6.02 x 1023 pennies. This amount is equivalent to 7 stacks of pennies from the Earth to the moon. Units for Avogadros Number HOFBrINCl Remember:

1 mole Mg= 6.02 x 1023 atoms. 1 mole NaCl= 6.02 x 1023 molecules. 1 mole Cl2 = 6.02 x 1023 molecules. 1 mole SO4-2 = 6.02 x 1023 ions. Calculating Formula Mass Calculate the formula mass of NaCl. 6 17 Na Cl 22.98

97 35.45 3 22.99 g + 35.45 g = 58.44 g1 mole of NaCl (6.02 Therefore, x 1023 molecules) has a mass of 58.44 g Calculating Formula Mass Calculate the formula mass of K2O. 19 6 K

O 39.09 83 15.99 94 2(39.10) g + 16.00 g = 94.2 g 1 mole of K2O (6.02 x Therefore, 1023 molecules) has a mass of 94.2 g Calculating Formula Mass Calculate the formula mass of (NH4)2SO4. 7 1

16 6 N H S O 14.00 67 1.007 94 32.06 6

15.99 94 2(14.01) g + 8(1.01) g + (32.01) + 4(16.00) g = 132.11 g Therefore, 1 mole of (NH4)2SO4 (6.02 x 1023 molecules) has a mass of 132.11 g Calculating Formula Calculate theMass formula mass of . This type of formula

is called a hydrate. CuSO 5H 4 2O. 29 16 1 It is a salt with water 6 physically attached to it. Cu S O H Example: A salt container with rice

63.54 32.06 15.99 1.007 intermixed. 6 water6 is physically 94 94 Since the attached how 63.55 g it+be 32.01g + 4(16.00) g + could removed? 5[2(1.01)+16.00] = 249.56 g .

Therefore, 1 mole of CuSO4 5 By heating. When the 23 water is removed H O (6.02 x 10 molecules) 2 the remaining salt is called anhydrous. has