Good Day! 11/23/2015 Starter: = 2! Please explain why this is true. Today we will be… First doing a very thourough cleaning of the lab equipment. Learning about the wonderful break through in chemistry, called the mole. Answer: 2 H O 2 = 2 H 2 O The crazy thing is if you take 2 liters of Hydrogen, and 1 liter of Oxygen, they will produce 2 liters of Water Vapor.

Notes on THE MOLE (Not the animal) (Not the internal spy) (something very different)

Avogadro’s Full Name: Lorenzo Romano Amedeo Carlo Avogadro di Quaregna – e - di Cerreto (Amedeo Avogadro) This man is not famous for his striking good looks, he’s famous for solving a problem.

Problem: Individual atoms cannot be weighed or massed, or counted. There was no way to determine if elements reacted by their atoms (Cl) or by a molecule (Cl 2 ).

Assumption: Gaseous elements CAN consist of polyatomic molecules. (Molecules with more than one element like Cl 2 or O 2 )

Amedeo Avogadro Hypothesis: Equal volumes of different gases at the same temperature and pressure contain equal numbers of particles. Amadeo Avogadro H 2 hydrogen CH 4 methane

Another way to say this is that even though Methane is way heavier and bigger (H 2 = 2 protons, CH 4 = 10 protons, & 6 neutrons, so about 8 times as large/heavy.) 1 liter of Hydrogen would have the EXACT same number of particles as 1 liter of Methane! The beauty of this is that it would explain the density issue. (hydrogen balloons float, and methane balloons sink) H 2 hydrogen CH 4 methane The boldness of his hypothesis

Video

This was a huge Breakthrough We could know the quantities that things were combining to make. We could figure out that water was 2 parts hydrogen and 1 part oxygen! From that we could deduce why they would combine like this.

Avogadro’s Number 6.02 x is called “Avogadro’s Number” in honor of the Italian chemist Amedeo Avogadro ( ). Amadeo Avogadro I didn’t discover it. Its just named after me!

The Mole 1 dozen = 1 gross = 1 ream = 1 mole = x If you gather up 6.02 x Carbon 12 atoms it would weigh exactly 12 grams. For this reason we choose the number 6.02 x It makes things easier when you are weighing out materials.

The Names 1 mole = atoms molecules formula units 6.02 x (elements) (nonmetals) (cation-anion) Representative Particles: 6.02 x = 602,000,000,000,000,000,000, ,000,000,000,000 billion. 602,000,000,000 trillion.

2.How many molecules of carbon dioxide are in 2.00 moles of CO 2 ?

2.How many molecules of carbon dioxide are in 2.00 moles of CO 2 ? 1 mole CO 2 = 6.02 x molecules CO 2 Conversion factor: 2.00 mol CO 2 x= molec. CO 2 1 mole = 6.02 x representative particles CO 2 is made of all nonmetals so rep. particles are “molecules” mol CO 2 molec. CO 2

2.How many molecules of carbon dioxide are in 2.00 moles of CO 2 ? 1 mole CO 2 = 6.02 x molecules CO 2 Conversion factor: 2.00 mol CO 2 x= molec. CO 2 mol CO 2 molec. CO x On calculator: 2.00 x (6.02 x ) = x Round to 3 sig. figs x molec. CO 2

Now for Molar Mass The wonderful thing about the mole is that it allows us to use mass when we are working with compounds but the trick is that you need to know how to calculate the mass of an given compound. Link to Molar Mass

Molar Mass The mass in grams of 1 mole of a substance. 1 H mole H = 1.01 g H

Calculating Molar Mass Ammonium Chloride g = g NH 4 Cl g x g x g g g x 1 7 N H Cl 35.45

Calculating Molar Mass Aluminum nitrate g) = = g Al(NO 3 ) g x g x g (14.01 g g x g Al N O 16.00

Alternate method Aluminum nitrate g = g Al(NO 3 ) g x g x g g g x 9 13 Al N O 16.00

1. Convert 3.00 moles of ammonia, NH 3, to grams of ammonia.

1 mole NH 3 = ?? g NH 3 Conversion factor: 3.00 mol NH 3 x= g NH 3 You have to find molar mass. (Use Periodic Table) mol NH 3 g NH 3

17.04 g NH g NH 3 NH g 1.01 g x g g g = x 1 Molar mass of ammonia. 7 N H mole NH 3 = g NH 3

1. Convert 3.00 moles of ammonia, NH 3, to grams of ammonia. 1 mole NH 3 = g NH 3 Conversion factor: 3.00 mol NH 3 x= g NH 3 mol NH 3 g NH 3 NH x 1 x g g = g/mol On calculator: 3.00 x = Round to 3 sig. figs g NH 3

And now for lots and lots of practice

3.How many moles of oxygen are in 44.8 L of oxygen, O 2 ? 1 mole O 2 = 22.4 L O 2 Conversion factor: 44.8 L O 2 x= moles O 2 1 mole = 22.4 L (for any STP) L O 2 mol O On calculator: 44.8 ÷ 22.4 = 2 Show to 3 sig. figs moles O 2

4. How many grams of lithium are in 3.50 moles of lithium? 1 mole Li = g Li Conversion factor: 3.50 mol Li x= g Li mol Li g Li On calculator: 3.50 x 6.94 = Round to 3 sig. figs g Li

5. How many moles of lithium are in 18.2 grams of lithium? 1 mole Li = g Li Conversion factor: 18.2 g Li x= mol Li g Li mol Li On calculator: 18.2 ÷ 6.94 = Round to 3 sig. figs mol Li