Ch. 10- The Mole Why- Within the next 2 months we will be working with chemical quantities. Determining what a reaction will produce or how much we need to go into a reaction with. These math skills can be applied across all science, ALL professions and many day to day life activities.

Measuring Matter Count, Mass, Volume…… Units indicating a specific number of items Examples???? Remember your dimensional analysis….well lets get those gears agrinding What is the mass of 90 apples if 1 dozen of the apples has a mass of 2.0kg

Jan 25- “Mole Day” Hey you….don’t be miserable today…you don’t want to be labeled as being dismole Why is it hard to count atoms, ions, or molecules 1x1? We as chemists use the mole (mol) in the same way we use dozen 1 mole = 6.02 x representative particles Avogadro’s number- named after him to honor his work on molecular theories

How big is a mole? If you count to 6.02 x 10 23, one number per second, how long will it take? 6.02 x x 1min/60sec x 1hr/60min x 1 day/24 hr x 1 yr/365 days = 1.9 x 1016 years = 19 quadrillion years! The earth is 4.6 billion years old, so that’s 4 million times the earth’s age!

Representative particles Refers the the species present in a substance Na = atoms CO 2 = molecules NaCl = formula unit So…… 1 mole of Na = 6.02 x atoms 1 mole of CO 2 = 6.02 x molecules 1 mole of NaCl = 6.02 x formula units

Mole Calculations Representative particlemole The magnesium we have used in labs is used to make aircraft, auto wheels, tools, and garden furniture. How many moles of magnesium is 1.25 x atoms of Mg 1.25 x atoms Mg x ______1 mole _______ = 6.02 x atoms Mg 2.08 x mol Mg

Cont. Moles Representative Particles Propane gas (C 3 H 8 ) is used in cooking and heating. How many molecules are in 2.12 moles of propane mol C 3 H 6 x 6.02 x molecules C 3 H 6 = 1 mol C 3 H 6

Practice 1. What is Avogadro’s #? 2. What is the representative particle for MgS? 3. How many formula units are in 2.34 moles of NaNO 3 ? 4. How many moles are in 3.48 x atoms of Li?

Remember our friend amu ? Decimal from periodic table Relative values based on the mass of Carbon-12 isotope Since ratio is relative, changing the unit will not change the ratio Grams is convenient to use in lab so….lets us it

Molar Mass (IMPORTANT)

Molar mass of Compounds Simply…add the masses of all the elements in the compound together Ex. SO 3 EX. C 9 H 11 NO 2 On your own…try 1.) K 3 PO 4 2.) Al 2 (SO 4 ) 3

Mole Land…. Where the fun is multiplied by 6.02 x times

MoleMass problems Use molar mass to convert between moles and mass When aluminum reacts with oxygen in the air a tough coating of aluminum oxide(Al 2 O 3 ) is formed. What is the mass of 9.45 mol of aluminum oxide? molar mass 9.45 mol Al 2 O 3 x 102.0g Al 2 O 3 = 964 g Al 2 O 3 1 mole Al 2 O 3

MassMole Problems How many moles of Iron (III) Oxide are contained in 92.2 g of pure Fe 2 O 3 ? 92.2 g Fe 2 O 3 x 1 mole Fe 2 O 3 = mole Fe 2 O g Fe 2 O 3 molar mass

Molar Volume Avogadro’s hypothesis- equal volumes of gases at the same temp. and pressure contain equal number of particles Volume measured at STP ( Standard Temp. and Pressure) 0°C and 101.3kPa (1 atm) Molar volume = At STP, 1 mole or 6.02 x representative particles, of any gas occupies a volume of 22.4 L.

Mole Volume Problems SO 2 is a gas produced by the burning of coal and contributes to the pollution of the environment. Determine the volume, in L, of.60 mol SO 2 at STP..60 mol SO 2 x __22.4 L = 13 L SO 2 1 mol SO 2 Molar Volume

Volume Mole Problems How many moles would be contained in.200 L of H L H 2 x 1 mole H 2 = 8.93 x mol H L H 2 Molar volume

% Composition Relative amounts of the elements in a compound How important in the real world % mass of element = _mass of element_ x 100% mass of compound

% Composition from mass data When a 13.60g sample of a compound containing only Mg and O is decomposed, 5.40g of O is obtained. What is the % composition of this compound? % O = _mass of O_ x 100% = 8.20 g x 100% = 60.3 % mass of MgO 13.60g % Mg= _mass of Mg__ x 100% = 5.40 g x 100% = 39.7% mass of MgO 13.60g

% Composition from Chemical Formula % mass = mass of element in 1 mol compound molar mass of compound Propane (C 3 H 8 ) is commonly used in gas grills. What is the percent composition of Propane? % C = 36.0g x 100% = 81.8% 44.0g % H = 8.0g x 100% = 18% 44.0g