The Mole

What is a mole? A mole is a QUANTITY of whatever you are measuring… 1 mole = 6.02 x of whatever you are measuring Just like 1 dozen = 12 of whatever you are measuring Or a couple of things = 2 things

What is a mole? In chemistry a mole measures the number of atoms or molecules 1 mole = 6.02 x atoms or molecules Why? 6.02 x is the number of carbon atoms in grams of Carbon 6.02 x is also known as AVAGADRO’S NUMBER

How Big Is a Mole? The volume occupied by one mole of softballs would be about the size of the Earth.

How many… dollars would you have if you have 2 moles of dollars? We would find this out by converting from moles to dollars using Avogadro's number We do this by doing a unit conversion

Unit Conversion Set Up 1.Write down your starting amount 2.Write down your conversion factor (__ starting amount = ___ ending amount) make sure that your units cancel out 3.Complete the multiplication or division problem to find the end amount

Converting from moles  things # of moles x 6.02 x things = # of things 1 mole How many dollars would you have if you have 2 moles of dollars? 2 moles x 6.02 x dollars = 1.2 x dollars 1 mole

More Examples How many atoms of water would you have if you have 3 moles of water? How many atoms of Helium would you have if you have 5 moles of Helium?

Converting from things  moles # of things x _____1 mole ___ = # of moles 6.02 x things It would take 2,103,674,750 pennies to circle the earth, how many moles is this? 2,103,674,750 pennies x ___1 mole _ = 3.49 × moles 6.02 x pennies

More Examples If you have 9,000,000 atoms of water how many moles of water would you have? If you have 7,500,000 atoms of Helium how many moles of Helium would you have?

SIMPLE GRAM – MOLE CONVERSIONS

Review 1 mole = 6.02 x “things” In chemistry those “things” are particles like atoms and molecules When converting between atoms and moles it doesn’t matter what the type of molecules or atoms are. The conversion is the same whether you are converting Water, Sodium, or any other element/molecule

Today We are going to learn two more conversions: Grams to moles Moles to grams When converting between grams and moles you need to look at WHAT you are converting. The atomic mass of the element is your conversion factor The atomic mass of an element is the number of grams of that element in 1 mole

Converting between grams and moles Grams to moles: DIVIDE by mass of element # of grams x ___1 mole ___ = # of moles atomic mass Moles to grams: MULTIPLY by mass of element # of moles x atomic mass = # of grams 1 mole Where do you find the atomic mass of an element?

Grams  Moles Examples You have 20 grams of Helium, how many moles do you have? 20 grams x ___1 mole ___ = 5 moles of Helium 4.00 grams You have 50 grams of Oxygen, how many moles do you have?

Moles  Grams Examples You have 3 moles of Chlorine, how many grams of chlorine do you have? 3 moles x grams = grams 1 mole You have 4 moles of Lithium, how many grams do you have?

ADVANCED GRAM – MOLE CONVERSIONS

Molar Mass When you are converting between grams and moles for a molecule (example – H 2 O) you need to use the molar mass to convert The molar mass is the atomic mass of each element in the molecule added up

Calculating Molar Mass Calculating Molar Mass of H 2 O: H: x 2There are 2 Hydrogen’s so you = 2.016have to multiply the weight of Hydrogen by 2 O: = grams

Another example… Calculate the molar mass of KMnO 4 (#1 on WS) K = Mn = O =

Calculating Molar Mass with Parenthesis What is the molar mass of Ca(NO 3 ) 2 ?(#4 on WS) Number outside the () gets multiplied to everything inside the () Ca = N = O =