CELEBRITY CHEMIST of THE CELEBRITY CHEMIST of THE DAYDAY

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MOLE CONCEPTMOLE CONCEPT

Number of particles in one Number of particles in one mole = Avogadro’s numbermole = Avogadro’s number = =

6.02 X 10 6.02 X 10 2323

602 000 000 000 000 000 000 602 000 000 000 000 000 000 000000

Unit of measure for matter

How many molecules are present How many molecules are present in 4 moles of Hin 4 moles of H22O? How many O? How many atoms are present?atoms are present?SOLUTION:SOLUTION:One mole of any substance contains One mole of any substance contains 6.02 6.02

X 10 X 10 2323 particles, therefore:particles, therefore:(4 moles) (4 moles) 6.02 X 10 6.02 X 10 2323 = = 2.41 X 10 2.41 X 10 2424

moleculesmolecules molemoleSince there are 3 atoms per HSince there are 3 atoms per H22O molecule, O molecule, the total number of atoms is:the total number of atoms is:((3 atoms3 atoms)) 2.41 X 10 2.41 X 10 2424 molecules = molecules = 7.23 X 10 7.23 X 10

24 24 atomsatomsmoleculemolecule

Mass of one moleMass of one mole = mass of one = mass of one atom/molecule expressed in grams atom/molecule expressed in grams rather than atomic mass unit (amu)rather than atomic mass unit (amu)

1 amu = based on 1/12 the mass of C-1 amu = based on 1/12 the mass of C-12 (most common carbon isotope)12 (most common carbon isotope)

Example: Example: 1 1 atomatom of He = 4 of He = 4 amusamus1 1 molemole of He = 4 of He = 4 gramsgrams

1 1 moleculemolecule of O of O22 = 2 x 16 amus/O = = 2 x 16 amus/O = 3232 amus amus

1 1 molemole of O of O22 = 32 = 32 gramsgrams

MOLAR MASSMOLAR MASS

FORMULAFORMULA

GIVEN GIVEN WEIGHTWEIGHT

MOLAR MASSMOLAR MASS

NUMBER OF MOLES

=

n =GW

MM

1.1. How many moles of How many moles of carbon atoms are carbon atoms are contained in 4 g of contained in 4 g of carbon?carbon?The atomic mass of carbon is 12 amu, The atomic mass of carbon is 12 amu,

therefore the molar mass of carbon therefore the molar mass of carbon is 12 grams.is 12 grams.

4 g X 4 g X 1 mole1 mole = = 0.333 mole C 0.333 mole C

12 g12 g

CONVERSION FACTOR

(from periodic table)

2. How many moles of 2. How many moles of water are there in 36 g of water are there in 36 g of water?water?

SOLUTION:SOLUTION:

The molecular mass of HThe molecular mass of H22O is 18 O is 18 amu.amu.

The molar mass of HThe molar mass of H22O is 18 g.O is 18 g.

36 g 36 g X X 1 mole1 mole = = 2 moles 2 moles HH22OO

18 g18 g

3. Calculate the mass of 3. Calculate the mass of aluminum carbonate aluminum carbonate ((AlAl22(CO(CO33))33)) in 5.85 moles in 5.85 moles of the compound.of the compound.In AlIn Al22(CO(CO33))33 , there are , there are 2 Al2 Al, , 3 C3 C and and 9 O9 O

Formula mass = (Formula mass = (2 2 X X 27 g/Al27 g/Al) + ) +

((3 3 X X 12 g/C12 g/C) + () + (99 X X 16 g/O16 g/O) = ) = 234 g234 g

Molar mass = 234 gMolar mass = 234 g

Mass of AlMass of Al22(CO(CO33))33 = 5.85 moles X = 5.85 moles X 234 g 234 g = 1369 g= 1369 g

Volume of one mole of solid and liquidsVolume of one mole of solid and liquids = varies from = varies from one substance to another based on their densityone substance to another based on their density

Example:Example:

1 mole of H1 mole of H22OO (density = 1.00 g/mL) has a mass of 18 (density = 1.00 g/mL) has a mass of 18 grams and will therefore occupy grams and will therefore occupy 18 mL18 mL

1 mole of NaCl1 mole of NaCl (density = 2.165 g/mL) has a mass 58 (density = 2.165 g/mL) has a mass 58 g g

(Na = 23 g + Cl = 35 g) and would occupy (Na = 23 g + Cl = 35 g) and would occupy a a volume of 26.8volume of 26.8 mLmL (58 g /2.165 g/mL) (58 g /2.165 g/mL)

Volume of one mole of gasVolume of one mole of gas =equal to =equal to 22.4 liters22.4 liters at at standard temperature (0standard temperature (0ooC) and pressure (1 atm or C) and pressure (1 atm or 760 mm Hg) (STP) 760 mm Hg) (STP)

1 mole of O1 mole of O22 gas = gas = 22.4 L at STP22.4 L at STP

1 mole of He = 1 mole of He = 22.4 L at STP22.4 L at STP

MOLAR VOLUMEMOLAR VOLUME

1.1. How many moles of How many moles of nitrogen are present in nitrogen are present in 4.48 liters of nitrogen at 4.48 liters of nitrogen at STP?STP?Since there are 22.4 liters of any gas at Since there are 22.4 liters of any gas at

STP, the solution isSTP, the solution is

4.48 L X 4.48 L X 1 mole1 mole = = 0.2 moles N0.2 moles N22

22.4 L22.4 L

CONVERSION FACTOR

PERCENT PERCENT COMPOSITIONCOMPOSITION

- Percent by mass of each element Percent by mass of each element present in the compound.present in the compound.

% by % by mass mass of of each each elemeelementnt

Total mass of elementTotal mass of element X 100%X 100%Total mass of Total mass of compoundcompound

=

What is the percentage What is the percentage composition of Hcomposition of H22O?O?

% H % H in in HH22O O

2 X 1 2 X 1 g x g x 100% = 100% = 18 g 18 g

11.11 %11.11 %

% O % O in in HH22OO

1 X 16 1 X 16 g x g x 100% = 100% = 18 g18 g

88.8988.89%%

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TO CHECK = 100.00%