Today is Tuesday,April 10th, 2018

Pre-Class:Take a look at the graduated cylinder on the front desk.

There are 18 mL of water in it. If you had to guess, about how many water molecules are in

there?

Also: You need your periodic table and calculator.

Stuff You Need:✓Calculator✓Periodic Table

In This Lesson:Unit 4:

StoichiometryMoles and Mole

Conversions(Lesson 1 of 4)

Today’s Agenda

• The Mole!

• Working with Moles

• Where is this in my book?

– P. 306 and following…

By the end of this lesson…

• You should be able to calculate the number of moles in a quantity of a substance.

The Mole

• 1 dozen of something equals how many?• 12

• 1 mole of something equals how many?• 6.02 x 1023 (or

602,000,000,000,000,000,000,000)

• For chemistry, a mole of a substance equals 6.02 x 1023 representative particles.• 1 mole of iron = 6.02 x 1023 iron atoms.

• 1 mole of carbon dioxide = 6.02 x 1023 carbon dioxide molecules.

• 1 mole of sodium chloride = 6.02 x 1023 sodium chloride formula units.

Did you get that?

• The smallest unit of a(n) ____ is a(n) ____:

– element…atom

– covalent compound…molecule

– ionic compound…formula unit

Avogadro’s Number

• 6.02 x 1023 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855).

• He did not actually discover the number, however.

• Fun fact: Avogadro’s full name was Lorenzo Romano Amadeo Carlo Avogadro, Count of Quarequa and Cerreto.

Amadeo Avogadro

Avogadro’s Number

Moles

Quick Mole Questions

• 1 Dozen Cars

• 1 Dozen Tricycles

– Of which vehicle do I have more?

• I have the same amount of each vehicle.

• 1 Mole of Molecule A = C2H6

• 1 Mole of Molecule B = C8H8

– Of which molecule do I have more?

• I have the same amount of each molecule!

Quick Mole Questions

• 1 Dozen Cars

• 1 Dozen Tricycles

– Do I have more car wheels or tricycle wheels?

• More car wheels (each car has 4, each tricycle has 3).

• 1 Mole of Molecule A = C2H6

• 1 Mole of Molecule B = C8H8

– Do I have more atoms from Molecule A or Molecule B?

• More atoms from Molecule B (each B molecule has 16 atoms, each A molecule has 8 atoms).

How big is a mole?

• Video!

Molar Mass

• Molar mass (also known as formula mass) is the total atomic mass of a compound or element.

– In other words, just add all the atomic masses of the elements in a compound together.

• Molar mass equals the mass in grams of one mole of a substance.

– One mole of hydrogen (H) has a mass of ~1.0079 g.

– One mole of hydrogen gas (H2) has a mass of ~2.016 g.

• Molar mass is measured in grams per mole or g/mol.

Moles and Gases

• For solids, liquids, and gases, the molar mass of a substance equals one mole.

• Also for gases, 22.4 Liters (L) = 1 mole.

– This works for any gas at STP (standard temperature and pressure).

• This is called the molar volume.

– Like the molar mass, only…you know…volume.

How much room (L)

So…

1 Mole

22.4 Liters (Gas)

So…

1 Mole

Molar Mass Practice

• Calculate the molar mass of carbon dioxide.

• Formula of carbon dioxide = CO2.

• Carbon mass = 12.0107 g/mol.

• Oxygen mass = 15.9994 g/mol.

• 12.0107 + 15.9994 * 2 = 44.0095 g/mol.

• So, one mole of CO2, or 6.02 x 1023 molecules, has a mass of about 44 grams.

Hydrates

• While we’re on the topic of formula mass, we should talk about hydrates.

• Hydrates are substances, typically salts, that contain water within their chemical bonds.

• Because of this, their formulas include H2O.

– Example: CoCl2 • 6H2O

– This is cobalt (II) chloride with six attached water molecules.

Naming Hydrates

• CoCl2 • 6H2O is “Cobalt II chloride hexahydrate.”

• CoCl2 • 5H2O is “Cobalt II chloride pentahydrate.”

– I think you get the idea.

• CoCl2 is “Cobalt II chloride anhydrous,” which just means it is not hydrated.

Hydrates

Hydrate Molar Mass

• We’ll look more at hydrates when we do our Formula of a Hydrate lab. For now, know this:– To calculate molar mass of a hydrate, add the mass of

water (times the coefficient) to the rest of the formula’s mass.

– Example: CoCl2 • 6H2O• Add up Co’s mass, Cl’s mass (times two) and water’s mass

(times six).

• 58.93 + 35.45 * 2 + 18.0148 * 6 = 237.9188 g/mol.

– The • looks like a multiplication symbol, but don’t do that. That’d be bad.

Molar Mass Worksheet

• Let’s try a QUICK worksheet (Molar Mass) that will help you practice molar/formula mass.– Try 1/4 the problems. Any 10, as long as you do 10.– You must try at least one of 30, 39, or 40, and at least

one of your ten has to have parentheses.

• ( ) around something means the subscript outside them is distributive – you’ll need to do a little multiplication for those.– Example: Al2(SO4)3 – calculate SO4’s molar mass and

multiply by 3.– Similar to what is done for hydrates.

Mole Calculations

• Now that you know how to find the mass of a mole of something, it’s time to learn how to do some calculations relating to that.

• The good news is we’re still going to be using our old friend from unit analysis:

• The other good news is that I have a system for you to learn how to make these calculations.– It’s called the mole highway.

starting measurement target unit

given unit

The Mole Highway

Atoms, Molecules, or Formula Units

Molar Mass

1 mol

1 mol

Molar Mass

22.4 L

1 mol

1 mol

22.4 L

6.02x1023

Rep. Part.

1 mol

1 molxx xx x x

6.02x1023

Rep. Part.

Volume (L)Mass (g)

The Mole Highway

Atoms, Molecules, or Formula Units

Molar Mass Molar Mass 22.4 L 22.4 L 6.02x1023

Rep. Part.÷÷ ÷x x x

6.02x1023

Rep. Part.

Volume (L)Mass (g)

Mole Conversion Triforce

g

mol molar mass

L

mol 22.4

rep.part.

mol 6.02x1023

Mole Calculations

• How many grams of lithium are in 3.50 moles of lithium?

• There are 24.3 g of lithium in 3.50 mol.

3.50 mol g

mol= 24.3 g

6.941

1

Mole Calculations

• How many moles of lithium are in 18.2 grams of lithium?

• There are 2.62 mol of lithium in 18.2 g.

18.2 g mol

g= 2.62 mol

1

6.941

Mole Calculations

• How many atoms of lithium are in 3.50 moles of lithium?

• There are 2.11 x 1024 atoms of lithium in 3.50 mol.

3.50 mol atoms

mol= 2.11 x 1024 atoms

6.02 x 1023

1

The Big Idea

• As your Mole Highway shows:

– Moles Grams = Multiply

• (MGM)

– Grams Moles = Divide

Moles to Grams

2.550 moles of Cu2CrO4 619.9 grams

10.0 moles of NaCl 583 grams

3.00 moles of H2 6.05 grams

1.50 moles of potassium sulfate 261 grams

4.50 moles of sodium oxide 278 grams

1.95 moles of nitric acid 123 grams

2.20 moles of SnCl2 417 grams

3.27 moles of oxygen gas 105 grams

Grams to Moles

0.750 grams of Na2CO3 0.00708 moles

8.76 grams of NaOH 0.219 moles

25 grams of water 1.4 moles

88 grams of CO2 2.0 moles

25 grams of potassium permanganate 0.16 moles

17 grams of H2O2 0.50 moles

75.57 grams of potassium bromide 0.6351 moles

100.0 grams of KClO4 0.7218 moles

Let’s Talk About Gas

• You may have noticed another set of lanes on the mole highway for volume.

• When it comes to gases, we can also determine the volume a mole of a gas will take up (like we can determine the mass of a mole of something).

• One mole of any gas takes up 22.4 L at standard temperature and pressure.

– Molar mass doesn’t have anything to do with this.

• Conversions work the same way.

Mole Calculations

• How many liters do 2.00 moles of hydrogen gas occupy at standard temperature and pressure?

• 2.00 moles of H2 take up 44.8 L.

2.00 mol L

mol= 44.8 L

22.4

1

Mole Calculations

• How many moles are in 14.2 liters of argon gas at standard temperature and pressure?

• 14.2 L of Ar is 0.634 mol Ar.

14.2 L mol

L= 0.634 mol

1

22.4

The Big Idea

• As your Mole Highway shows:

– Moles Liters = Multiply

– Liters Moles = Divide

Moles to Liters…and vice versa…

5.42 moles of Rn 121 liters

19.5 moles of F2 437 liters

13.21 moles of Ne 295.9 liters

2.37 moles of nitrogen gas 53.1 liters

11.9 liters of CO2 0.531 moles

1.3 liters of O3 0.058 moles

3.00 liters of CO 0.134 moles

90.2 liters of sulfur hexafluoride 4.03 moles

Mole Calculations

• How many atoms are in fifteen moles of lead?

• In 15 moles of Pb, there are 9.0 x 1024 atoms.

15 mol atoms

mol= 9.0 x 1024 atoms

6.02 x 1023

1

6.02 x 1023

Mole Calculations

• How many moles are in 5.2 x 1024 molecules of F2?

• If you have 5.2 x 1024 molecules of F2, you have 8.6 moles.

5.2 x 1024 molecules mol

molecules= 8.6 moles

1

The Big Idea

• As your Mole Highway shows:

– Moles Representative Particles = Multiply

– Representative Particles Moles = Divide

Moles to Representative Particles…and vice versa…

4.22 moles of Rn 2.54 x 1024 atoms

1.95 moles of F2 1.17 x 1024 molecules

1.23 moles of Ne 7.40 x 1023 atoms

23.7 moles of ammonium chloride 1.43 x 1025 formula units

5.32 x 1023 molecules of CO 0.884 moles

1.30 x 1025 molecules of O2 21.6 moles

3.00 x 1024 molecules of Cl2 4.98 moles

9.020 x 1024 atoms of cobalt 14.98 moles

Practice

• Mole Conversions Worksheet

– #1-6 [4 is a challenge]

• Mole Conversion Table Worksheet

– Get as far as you can…

Two Step Mole Conversions

• Sometimes you’ll need to go from grams to liters or atoms to grams.

• In these cases, you’ll still use the mole highway, but you’ll have to use it for two steps.

• For example, let’s look at the path you’d take if you needed to go from grams to atoms.

The Mole Highway

Atoms, Molecules, or Formula Units

Molar Mass

1 mol

1 mol

Molar Mass

22.4 L

1 mol

1 mol

22.4 L

6.02x1023

Rep. Part.

1 mol

1 molxx xx x x

6.02x1023

Rep. Part.

Volume (L)Mass (g)

Mole Calculations

• How many atoms of lithium are in 18.2 grams of lithium?

• There are 1.58 x 1024 atoms of lithium in 18.2 g.

g

18.2 g= 1.58 x 1024

atoms

1

6.941

mol

mol

6.02 x 1023

1

atoms

Mole Calculations

• How many formula units of sodium chloride are in 14.0 grams of sodium chloride?

• There are 1.44 x 1023 units of NaCl in 14.0 g.

g

14.0 g= 1.44 x 1023

formula units

1

58.44

mol

mol

6.02 x 1023

1

funits

Mole Calculations

• How many grams of water are in 1.204 x 1024

molecules of water?

• 1.204 x 1024 molecules of water weigh 36.03 g.

molecules

1.204 x 1024

molecules= 36.03 g

1

6.02 x 1023

mol

mol

18.0148

1

g

Moles/Grams to Liters(and vice versa)

0.600 mol SO2 13.44 liters

16 mol N 358.4 liters

16 mol N2 358.4 liters

38.44 g SO2 13.44 liters

40 L CO2 (convert to moles) 1.79 moles

40 L CO2 (convert to grams) 78.59 grams

16 L CO (convert to moles) 0.71 moles

16 L CO (convert to grams) 20.07 grams

Practice

• Mole Conversions worksheet

– #7-12

Closure

• Quick interesting note:

– For some reason, it seems like every two-step mole conversion requires you to first divide, then multiply.

• Multiply or divide by what? You decide.

– Example: Grams to Liters:

• Divide by molar mass, multiply by 22.4.

Closure

• How many representative particles are in 71.91 grams of diatomic bromine?

• Br2 formula mass = 159.81 g/mol

• 71.91 g / 159.81 g/mol = 0.45 moles

• 0.45 moles x 6.02 x 1023 = 2.709 x 1023

particles.

1 mol Au

• What mass of gold contains twice as many atoms as 2.74 grams of silver?

• Au molar mass = 196.97 g/mol

• Ag molar mass = 107.87 g/mol

196.97 g Au2 mol Au

Mole Conversions Boss

1 mol Ag2.74 g Ag

107.87 g Ag

=

10.0 g Au

1 mol Ag

http://img1.wikia.nocookie.net/__cb20110523221131/villains/images/6/66/Bowser_SMG.jpg

1000 g1 kg

Mole Conversions Boss 2

• Automobiles in the US emit approximately 1.5 billion metric tons of carbon dioxide annually. How many liters is this at STP?

• 1 metric ton = 2204.6 pounds

• 2.2 pounds = 1 kilogram

https://www.fueleconomy.gov/feg/climate.shtml

2204.6 lbs1.5x109 t

1 t

=

7.7 x 1014 L

2.2 lbs 1 kg

1 mol

44.009 g

22.4 L

1 mol

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