WHAT IS A MOLE?

Moles: Measuring Matter

A UNIT OF MEASURE!!!A UNIT OF MEASURE!!!

1 mole = 6.02 x 1023 representative particles– atoms, molecules, formula units, ions– Also called Avogadro's number

Moles

1 mole = 6.02 x 1023 particles 1 mole is also equal to the molar masmolar mass of a substance molar mass = atomic mass with the units g/mol

*g/mol is the same as atomic mass except atomic mass has the units of amu

Molar mass of compoundsMolar mass of compounds – add up parts– Find the molar mass of KK22CrOCrO44

Molar Mass

CHALK LAB!!CHALK LAB!!

MAKE FLIP CHART: 4 SHEETS

Mole Conversions

particles to molesparticles to moles

# particles 1 mole

6.02 x 1023 particles moles to particlesmoles to particles

# moles 6.02 x 1023 particles

1 mole moles to mass (g)moles to mass (g)

moles molar mass =

1 mole

Mole Conversions

Mass (g) to molesMass (g) to moles

mass 1 mol =

molar mass Mass (g) to particlesMass (g) to particles

mass 1 mol 6.02 x 1023 particles

molar mass 1 mol particles to mass (g)particles to mass (g)

particles 1 mol molar mass

6.02 x 1023 particles 1 mol

MOLES to Particles

Converting moles to particles– Conversion Factors

# moles x 6.02 x 1023 particles

1 molConvert 3.5 moles sucrose to molecules

Moles continued

Converting particles to moles

# particles x 1 mole =

6.02 x 1023 particlesCalculate the # moles in 4.50 x 10Calculate the # moles in 4.50 x 102424 atoms Zn atoms Zn

Homework: 2/7

Do problems 1, 6, 7, 16, 17, & 20

Moles: Mass and the Mole

Moles to mass:Moles to mass:

# moles x # grams

1 mol– How many grams are in 3.00 mol Mn?

Moles: Mass and the Mole

mass to moles:

mass x 1 mol

#grams– How many moles are in 525 g Ca?

Homework: 2/8

Do problems 8, 9, 12, 13 & 18

Moles -2: Mass and the Mole

atoms to mass:# particles x 1 mol x # grams

6.02 x 1023 particles 1 mol

– How much mass is in 5.50 x 10How much mass is in 5.50 x 102222 atoms of atoms of helium?helium?

mass to atoms:mass x 1 mol x 6.02 x 1023atoms

#grams 1 mol– How many atoms of gold in 25.0 g?How many atoms of gold in 25.0 g?

Homework 2/9

Do problems: 10, 11, 14 & 15

QUIZ Tomorrow over mole conversions!!

Moles -4: Empirical and Molecular Formulas

percent composition

mass of element x 100 = % by mass

mass of compound

• percent always adds up to 100– Find % of H and O in water

Moles -4 continued

Empirical formula – smallest whole # mole ratio of the elements

* May or may not be actual molecular formula– To get:

1. Change g to mol

2. Get mole ratio

3. The ratios are the subscripts*If you are given % composition: assume % is grams

Find the empirical formula of a sample with 40.05 g S and 59.95 g O.

Moles -4 continued

Molecular formula – specific # of atoms of each element in compound

experimentally determined molar mass = n

mass of empirical formulamultiply n by empirical formula subscripts

molecular formula = (empirical formula)n

Problem: The empirical formula of a substance is CH. The molecular mass of the compound is 78 amu. What is the molecular formula of the compound?

EMPIRICAL & MOLECULAR FORMULA PRACTICE

– Chemical analysis indicates a sample is composed of 40.68% C, 5.08% H and 54.24% O and has a molar mass of 118.1 g/mol. Determine the empirical and molecular formulas of succinic acid

Moles: Moles of Compounds

YOU can find moles of a part of a compound– How many moles of F are in 5.50 moles

CCl2F2?

* Get ratio from formula.– Determine the number of moles of Al ions in

1.25 mol Al2O3

Moles -5: The formula for a Hydrate

Hydrate – compound with a specific # of water molecules bound to its atoms

Methane Hydrate

Naming Hydrates

Naming:Naming:– name salt • prefix hydrate

CaCl2•2H2Ocalcium chloride dihydrate

– Prefixes are the same as those used for covalent compounds

– Anhydrous – without water used to store water or as drying agents

– Used to store solar energy i.e. sodium sulfate decahydrate

Hydrate Practice

1. Write the chemical formula of lithium nitrate trihydrate.

2. Write the chemical formula for sodium sulfate decahydrate.

3. What is the molar mass of the hydrate lithium nitrate trihydrate?

4. What is the percent of water in sodium sulfate decahydrate?