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### The Mole

### The Mole

Outcomes – January 30-Feb1

- 1. Receive two mole bucks for having the practice quiz done priorto the quiz!
- 2. Revisit naming and formula writing, figuring out how to read the flow chart given
- 3. Learn what a mole is and why we use the unit “mole” to describe quantity of atoms and molecules!

Bellwork Feb. 7-8

- How many atoms of each element are in the reactants side of the following equation:

2 FeCl3 + 1 Be3(PO4)2 --> 3 BeCl2 + 2 FePO4

Now, do the same for the products side.

- What do you notice about the number of atoms?

What is it called when the number and mass on both sides of the equation are equivalent to each other?

Outcomes Feb 7-8

- Schedule a time with my teacher to re-take Unit 7 Quiz during Office Hours or Seminar, if I need to
- Be an ace at calculating molar mass for atoms and for compounds
- Write down that the Unit 8 Test is February 13 (A)-14 (B)

Exit Quiz Feb 7-8Please use a full sheet of paper!

- 1. Which type of compound, ionic or covalent, do you use prefixes for?
- 2. What always goes first in the name of ionic compounds: the cation or the anion?
- 3. Write the molar mass for one mole of Tungsten, in grams
- 4. Write the formula: Magnesium chloride
- 5. How many atoms are in one mole of Carbon?
- 6. How many grams are in two moles of Na2SO4?

Exit Quiz – Alternate –Feb 7-8

- You are expected to draw the conversions chart and to have your calculator in Chemistry class from now on!
- 1. How many moles of Hydrogen are in 28.9 grams of Hydrogen?
- 2. How many atoms of Germanium are in 4.2 moles of Germanium?
- 3. What must you sum up when calculating the molar mass of a compound?
- 4. If you have a coefficient of 2 for a compound, what happens to the total number of atoms for an element in the compound?

Outcomes Feb 1-2

- 1. Learn how to calculate molar mass
- 2. Practice writing names and formulas for ionic and covalent compounds
- 3. Ace an exit quiz which tests your mastery of naming and formula writing and moles

Bellwork – Feb 1-2

- 1. Write the formula for lithium carbonate
- 2. How many atoms of each element are in: 4LiC2H3O2 and 4Mg3(SO4)2
- 3. Write the name for Si2O4
- 4. How many moles are in 36.03 particles of Carbon? (Hint: use 6.02x10^23 _______ = 1 mole ____)

Bell work

- Determine the number of atoms in each of the following (ie: 1 carbon atom, 3 oxygen atoms, etc):

Li2SO4 Al(OH)3 N2O3

CCl4 Mg3(PO4)2 BeCl2

- Name them.

Agenda

- Bell work
- The mole
- Practice with conversions
- Naming Challenge
- Homework: Molar mass and conversions homework

Honors

- Is anyone interested in joining honors for second semester?
- Pick up an application! The due date has been extended.

What is a mole?

- Quantity of particles
- Volume of gases at STP (Standard Temp and Pressure
- We’ll get to this later
- Mole to mole ratios
- Molar mass

Quantity of Particles

- 1 mole = 6.02 x 1023 particles
- If I have a mole of M&Ms, how many M&Ms do I have?
- If I have a mole of pennies, how many pennies do I have?

6.02 x 1023 atoms

6.02 x 1023 Watermelon seeds would be found inside a melon slightly larger than the moon.

6.02 x 1023 Pennies would make at least 7 stacks that would reach the moon.

6.02 x 1023 Grains of sand would be more than all of the sand on Miami Beach.

6.02 x 1023 Blood cells would be more than the total number of blood cells found in every human on Earth.

A 1 Liter bottle of water contains 55.5 moles H2O.

A 5 pound bag of sugar contains 6.6 moles of C12H22O11.

There are 3 types of moles that live underground in North America: Eastern Mole, Hairy-Tailed Mole and Star-Nosed Mole.

6.02 x 1023 atoms

Why do we use moles?

- Atoms are very, very small.
- 1 atom of hydrogen weighs approximately 1.67 x 10-27 kg.
- As a result, it’s not very practical to do chemical reactions by counting out the number of atoms or molecules that will be reacting, because we’ll be counting for a very long time!

You’ve seen this before, because when working with a large number of objects, it’s frequently handy to use units that are easier to work with.

- 2 shoes = 1 pair
- 12 eggs = 1 dozen
- 144 pencils = 1 gross
- 500 sheets of paper = 1 ream
- 6.02 x 1023 atoms or molecules = 1 mole
- The idea behind moles is the same as the idea behind “dozens”, except that the number is much bigger.

Why don’t we use moles all the time in everyday life? Could we?

- Yes, we could.
- Although we could use moles to describe numbers of things that we work with everyday, it’s not really very practical.
- 1 mole of most objects that you work with on a daily basis is very, very large. For example, 1 mole of M&M’s would cover the continental United States to a depth of 125 km.

The mole (mol) is the amount of a substance that

contains as many elementary entities as there

are atoms in exactly 12.00 grams of 12C

1 mol = NA = 6.0221367 x 1023

Avogadro’s number (NA)

Molar Mass

eggs

- Mass of 1 mole of a compound
- Units: grams/mole (g/mol)

Molar mass is the mass of 1 mole of in grams

shoes

marbles

atoms

How to find the molar mass of a compound:

- Sum the masses of all of the atoms in the molecule
- Example: NaCl

Na:22.99 grams x1 atom = 22.99 g/mol

Cl: 35.45 grams x 1 atom =35.45 g/mol

Total: 58.44 grams/mol

Try on your own:

- Find the molar mass of Mg(NO3)2,
- MgCl2
- Fe(OH)2,
- Be3(PO4)2

Mg: 24.31 grams x 1 atom = 24.31 grams/mol

N: 14.01 grams x 2 atoms = 28.02 grams/mol

O: 16.00 grams x 6 atoms = 96.00 grams/mol

Total: 148.33 grams/mol

- MgCl2 95.21 g/mol
- Fe(OH)2 90 g/mol
- Be3(PO4)2 217 g/mol

Calculations

- How do you count out a mole of atoms?
- You don’t. Even if it were possible to count out individual atoms in a reasonable period of time, the equipment we have only measures “grams.”
- As a result, we need to be able to convert between atoms/molecules, moles, and grams.

Conversion factors

- 1 mole = _____ g (molar mass)
- 1 mole = 6.02 x 1023 atoms or molecules (Avogadro’s number)
- 1 always goes in front of moles!

Use this diagram

grams

Molecules

or atoms

Molar

mass

6.02 x 1023

moles

- Convert as usual
- Handy hint:
- In conversion factors, always write “1” in front of “moles”!
- ******YOU MUST ALWAYS GO THROUGH MOLES!!!********

If you match up what goes on top and what goes on the bottom, you don’t have to remember whether you multiply or divide

6.022 x 1023 atoms K

x

x

=

1 mol K

39.10 g K

How many atoms are in

0.551 g of potassium (K) ?

1 mol K = 39.10 g K

1 mol K = 6.022 x 1023 atoms K

0.551 g K

8.49 x 1021 atoms K

Let’s try a few more…………….

3.2

More Practice

- How many grams are in 2.1 moles of Be?
- How many molecules are in 6.3 moles of CH4?
- How many molecules are there in 11.1 grams of carbon dioxide?
- How many grams are in 4.1 x 1023 molecules of H2O?

More Practice

- How many grams are in 2.1 moles of Be? (18.9)
- How many molecules are in 6.3 moles of CH4? (3.79 x 1024 molecules)
- How many molecules are there in 11.1 grams of carbon dioxide? (1.51 x 1023 molecules)
- How many grams are in 4.1 x 1023 molecules of H2O? (18.7 g).

IP

- Molar mass and conversions IP

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