# WHAT IS A MOLE?.

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WHAT IS A MOLE?

Moles: Measuring Matter
A UNIT OF MEASURE!!! 1 mole = 6.02 x 1023 representative particles atoms, molecules, formula units, ions Also called Avogadro's number

Moles Molar mass of compounds – add up parts
1 mole = 6.02 x 1023 particles 1 mole is also equal to the molar 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 compounds – add up parts Find the molar mass of K2CrO4

Molar Mass

CHALK LAB!!

MAKE FLIP CHART: 4 SHEETS

Mole Conversions particles to moles # particles 1 mole
6.02 x 1023 particles moles to particles # moles x 1023 particles 1 mole moles to mass (g) moles molar mass =

Mole Conversions Mass (g) to moles mass 1 mol = molar mass
Mass (g) to particles mass mol x 1023 particles molar mass mol particles to mass (g) particles mol molar mass 6.02 x 1023 particles mol

MOLES to Particles Converting moles to particles Conversion Factors
# moles x x 1023 particles 1 mol Convert 3.5 moles sucrose to molecules

Moles continued Converting particles to moles # particles x 1 mole =
6.02 x 1023 particles Calculate the # moles in 4.50 x 1024 atoms Zn

Homework: 2/7 Do problems 1, 6, 7, 16, 17, & 20

Moles: Mass and the Mole
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 mol x # grams 6.02 x 1023 particles mol How much mass is in 5.50 x 1022 atoms of helium?

mass to atoms: mass x 1 mol x x 1023atoms #grams 1 mol How many atoms of gold in 25.0 g?

QUIZ Tomorrow over mole conversions!!
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: Change g to mol Get mole ratio The ratios are the subscripts *If you are given % composition: assume % is grams Find the empirical formula of a sample with g S and g O.

Moles -4 continued Molecular formula – specific # of atoms of each element in compound experimentally determined molar mass = n mass of empirical formula multiply 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 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: name salt • prefix hydrate CaCl2•2H2O
calcium 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 Write the chemical formula of lithium nitrate trihydrate. Write the chemical formula for sodium sulfate decahydrate. What is the molar mass of the hydrate lithium nitrate trihydrate? What is the percent of water in sodium sulfate decahydrate?