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Molar , Moles, and Avogadro’s Number • Bell schedule:

Period 1 - 8:00 - 9:07 (67 mins) Passing - 9:07 - 9:12 (5 mins) Period 2 S/L Activity - 9:12 - 9:59 (47 Mins) Recess - 9:59 - 10:09 (10 mins) Passing - 10:09 - 10:14 (5 mins) Period 2 - 10:14 - 11:21 - (67 mins) Lunch - 11:21 - 11:51 (30 mins) Passing - 11:51 - 11:56 (5 mins) Period 3 - 11:56 - 1:03 (67 mins) Passing - 1:03 - 1:08 (5 mins) Period 4 - 1:08 - 2:15 (67 mins) PSAT – Oct. 25th

• 10th and 11th grade Warm Up 10-16

1) Balance the following chemical equation:

Li2O + H2O  LiOH

2) How many reactants does the equation have?

3) In your balanced equation, how many of the product do you end up with? Molar Mass, Moles, and Avogadro’s Number Molar Mass

Molar mass is the mass of one

You calculate it by adding the of each in the molecule together

The units for molar mass are g/mol (grams per ) Molar Mass

Let’s look at CO2

C 12 * 1 = 12g/mol

O2 16 * 2 = 32g/mol

Molar Mass of CO2 = 12 + 32 = 44g/mol Practice

Find the molar mass of H2O

H2 1 * 2 = 2g/mol

O 16 * 1 = 16g/mol

Molar Mass of H2O = 2 + 16 = 18g/mol Molar Mass

You only every find molar mass for a single molecule, so ignore the coefficients!

Example: What is the molar mass of H2O in the chemical equation below?

6H2SO3  6H2O + 6SO2

The molar mass of H2O is still 18g/mol even though you have a coefficient of 6 Practice

2Ca(OH)2 + 2CO2  2CaCO3 + 2H2O

Find the molar mass of Ca(OH)2

Ca: 40 x 1 = 40g/mol O: 16 x 2 = 32g/mol H: 1 x 2 = 2g/mol

Molar Mass of Ca(OH)2 = 40 + 32 + 2 = 74g/mol What is a mole?

A mole (mol) is a standard unit that measures the mass of one molecule

The mass of a mol will be different based on the molecule. Que es un mole?

We just found that 1 molecule of H2O had a molar mass of 18g/mol

This means that 1 mol of H2O has a mass of 18g

We also found that 1 molecule of CO2 had a molar mass of 44g/mol

This means that 1 mol of CO2 has a mass of 44g What is a mole?

So we know 1 mol of H2O has a mass of 18g

…doesn’t that seem like a lot for a molecule?

18 grams is about the mass of 3 quarters!! What is a mole?

1 mole is actually 6.022 x 1023 particles

This means that if we took 602,200,000,000,000,000,000,000 molecules of H2O, they would have a mass of 18 grams together.

This is known as Avogadro’s Number: 6.022 x 1023

1 mole of any molecule has this many particles!

Amedeo Avogadro

There is 1 mole of water in 18mL….

So there are 602,200,000,000,000,000,000,000

molecules of H2O in 3.65 teaspoons Practice

How many CO2 molecules are in 1 mole of Dioxide?

6.022 x 1023 Practice How many Silver are in 1 mole of Silver?

6.022 x 1023 Practice

How many (NH4)2CO3 atoms are in 1 mole of ?

6.022 x 1023