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Stoichiometry: Conversions At the conclusion of our time together, you should be able to: 1. Convert a mole of a chemical to grams of that chemical 2. Convert grams of a chemical to moles of that chemical

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Review of Molar Mass The Mass of 1 mole (in grams) Equal to the numerical value of the average atomic mass (use your periodic table, round to 2 places) 1 mole of C atoms= g 1 mole of Mg atoms = g 1 mole of Cu atoms = g

Molar Mass of Molecules and Compounds Mass in grams of 1 mole is equal numerically to the sum of the atomic masses 1 mole of CaCl 2 = 1 mole Ca x g/mol + 2 moles Cl x g/mol = g/mol CaCl 2 1 mole of N 2 O 4 = g/mol N 2 O 4

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Learning Check! A. Molar Mass of K 2 O = ? g/mol g/mol B. Molar Mass of antacid Al(OH) 3 = ? g/mol g/mol

Calculations with Molar Mass molar mass Grams Moles

Molar Mass as a Conversion Factor Molar Mass of the Compound 1 mole or 1 mole Molar Mass of the Compound Note that the molar mass could be that of an atom OR a molecule!

Calculations with Molar Mass molar mass Grams Moles To convert Grams to Moles: x by 1 mole Molar Mass of the Compound

Calculations with Molar Mass molar mass Grams Moles To convert Moles to Grams: x by Molar Mass of the Compound 1 mole

Example of Converting Moles to Grams Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al ? g Al

1. Molar mass of Al1 mole Al = g Al 2. Conversion factors for Al g Al or 1 mol Al 1 mol Al g Al 3. Setup3.00 moles Al x g Al 1 mole Al Answer = g Al

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Stoichiometry: Conversions Let’s see if you can: 1. Convert a mole of a chemical to grams of that chemical 2. Convert grams of a chemical to moles of that chemical

Learning Check! The artificial sweetener aspartame (Nutra- Sweet) formula C 14 H 18 N 2 O 5 (MM = g) is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame?

Learning Check! = mol 225 g C 14 H 18 N 2 O 5 x 1 mol C 14 H 18 N 2 O g C 14 H 18 N 2 O 5

:Question #1 7.8 moles of Fe 2 O 3 # g Fe 2 O 3 = 7.8 mol Fe 2 O 3 x g Fe 2 O 3 1 mol Fe 2 O 3 = g Fe 2 O 3

Question # g K 2 SO 4 # mol K 2 SO 4 = g K 2 SO 4 x 1 mol K 2 SO g K 2 SO 4 = mol K 2 SO 4

Question # moles of CO 2 # g CO 2 = 1.22 mol CO 2 x 44.01g CO 2 1 mol CO 2 = 53.7 g CO 2

Stoichiometry: Conversions At the conclusion of our time together, you should be able to: 1. Convert a mole of a chemical to particles of that chemical 2. Convert particles of a chemical to moles of that chemical

Red-Neck Innovations:

Avogadro’s Number as a Conversion Factor 6.02 x particles 1 mole or 1 mole 6.02 x particles Note that a particle could be an atom OR a molecule!

Example of Avogadro’s Number as a Conversion Factor Number of moles of S in 1.8 x S atoms a) 1.0 mole S atoms b) 3.0 mole S atoms c) 1.1 x mole S atoms 1.8 x atoms S x 1 mol S 6.02 x atoms S = 2.99 mol S

Example of Avogadro’s Number as a Conversion Factor Number of atoms in mole of Al a) 500 Al atoms b) 6.02 x Al atoms c) 3.01 x Al atoms = 3.01 X atoms Al mol Alx 6.02 x atoms Al 1 mol Al

Stoichiometry: Conversions Let’s see if you can: 1. Convert a mole of a chemical to particles of that chemical 2. Convert particles of a chemical to moles of that chemical

And you thought Chemistry was bad with factor-label problems!!??

Question # moles = ? molecules # molecules = 4.5 mol = x molecules H 2 O = 2.7 x molecules H 2 O x 6.02 x molecules 1 mol

Question # x molecules = ? moles # moles = 6.02 x molecules = 1.00 x 10 1 moles = 10.0 moles x 1 mole 6.02 x molecules

Stoichiometry: Conversions At the conclusion of our time together, you should be able to: 1. Convert a mole of a chemical to particles or grams of that chemical 2. Convert grams of a chemical to moles 3. Convert particles of a chemical to moles 4. Convert particles to grams by going through the mole or the opposite direction.

Atoms/Molecules to Grams Since 6.02 X particles = 1 mole and 1 mole = molar mass (grams) You can convert atoms/molecules to moles and then moles to grams! (Two step process) You can’t go directly from atoms to grams!!!! You MUST go thru MOLES.

Calculations molar mass Avogadro’s number Grams Moles particles Everything must go through Moles!!!

Flowchart Atoms or Molecules Moles Mass (grams) Divide by 6.02 X Multiply by 6.02 X Multiply by atomic/molar mass from periodic table Divide by atomic/molar mass from periodic table

An Easier Flowchart Atoms or Molecules Moles Mass (grams)

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Atoms/Molecules to Grams How many atoms of Cu are present in 35.4 g of Cu? = 3.35 X atoms Cu 35.4 g Cux 1 mol Cu g Cu x 6.02x10 23 atoms Cu 1 mol Cu

Grams to Atoms/Molecules How many grams of Cu are present in 5.4 x atoms of Cu? = 57 g Cu 5.4 x atoms Cu x 1 mol Cu 6.02 x atoms Cu x g Cu 1 mol Cu

Familiar Saying Pulchritude does not extend below the surface of the derma. Beauty is only skin deep!!

Stoichiometry: Conversions Let’s see if you can: 1. Convert a mole of a chemical to particles or grams of that chemical 2. Convert grams of a chemical to moles 3. Convert particles of a chemical to moles 4. Convert particles to grams by going through the mole or the opposite direction.

Red-Neck Innovations:

Learning Check! How many molecules and atoms of oxygen are present in 78.1 g of oxygen? 78.1 g O 2 1 mol O X molecules O 2 2 atoms O 32.0 g O 2 1 mol O 2 1 molecule O x molecules of O x atoms of O

Learning Check! How many atoms of K are present in 78.4 g of K? 78.4 g Kx 1 mol K g K = 1.21 x atoms of K x 6.02 x atoms K 1 mol K

Learning Check! What is the mass (in grams) of 1.20 X molecules of glucose (C 6 H 12 O 6 )? 1.20 x mc C 6 H 12 O 6 x 1 mol C 6 H 12 O x mc = 359 g C 6 H 12 O 6 x 1 mol C 6 H 12 O g C 6 H 12 O 6

Extra Review Mass-Mole-Molecules: Determine the number of molecules in 73 g of water 73 g H 2 O # H 2 O molecules = x 1 mol H 2 O g H 2 O = 2.4 x molecules H 2 O x 6.02 x molecules 1 mol H 2 O