Mathematics of Mathematics of Chemical FormulasChemical Formulas

Chapter 8Chapter 8

P 175-195P 175-195

StoichiometryStoichiometry

Stoichiometry-Is the study of the Stoichiometry-Is the study of the quantitative relationships that can be quantitative relationships that can be derived from chemical formulas and from derived from chemical formulas and from chemical equations.chemical equations.

Formula massFormula mass

Formula mass- Of a substance is the sum Formula mass- Of a substance is the sum of the atomic masses of all the atoms of the atomic masses of all the atoms represented by the formula of the represented by the formula of the substance. This may be formula of an substance. This may be formula of an element, a molecular compound or ionic element, a molecular compound or ionic compoundcompound

Molecular MassMolecular Mass

Molecular Mass-Is the formula mass of a Molecular Mass-Is the formula mass of a molecular substancemolecular substance

Gram atomic massGram atomic mass

Gram atomic mass -Of an element is that Gram atomic mass -Of an element is that quantity of the element that has a mass in quantity of the element that has a mass in grams numerically equal to its atomic grams numerically equal to its atomic mass.mass.

Therefore 16 grams of oxygen is 1 gram Therefore 16 grams of oxygen is 1 gram atomic mass of oxygenatomic mass of oxygen

AKA gram-atomAKA gram-atom

Gram formula massGram formula mass

Gram formula mass is the quantity of a Gram formula mass is the quantity of a substance that has a mass in grams substance that has a mass in grams numerically equal to its formula mass.numerically equal to its formula mass.

Since the formula mass of water is 18 u Since the formula mass of water is 18 u the gram formula mass of water is 18 the gram formula mass of water is 18 gramsgrams

Gram molecular massGram molecular mass

Gram molecular mass = gram formula Gram molecular mass = gram formula mass in working with moleculesmass in working with molecules

MoleMole

Mole-aka mol is the number of atoms in 1 Mole-aka mol is the number of atoms in 1 gram atomic mass of an element. This gram atomic mass of an element. This number is 6.02 X 10number is 6.02 X 102323..

This can refer to 6.02 X 10This can refer to 6.02 X 102323 of anything of anything

MoleMole

RelationshipsRelationships

N atoms (6.02 X 10N atoms (6.02 X 102323 atoms) in 1 gram atoms) in 1 gram atomic mass of an element.atomic mass of an element.

There are N molecules (6.02 X10There are N molecules (6.02 X102323 ) ) molecules in 1 gram molecular mass of molecules in 1 gram molecular mass of every molecular substancevery molecular substanc

N formula units in 1 gram formula mass of N formula units in 1 gram formula mass of any substanceany substance

Mole RelationshipsMole Relationships

One mole of some common substances One mole of some common substances for example:for example:

AluminumAluminum

1 mole1 mole

1 gram atomic mass1 gram atomic mass

27 grams27 grams

6.02 X 106.02 X 102323 atoms atoms

Mole RelationshipsMole Relationships

One mole of some common substances One mole of some common substances for example:for example:

OxygenOxygen

1 mole1 mole

1 gram formula mass1 gram formula mass

32 grams32 grams

6.02 X 10 6.02 X 10 2323 molecules molecules

Mole relationshipsMole relationships

WaterWater

1 mole1 mole

1 gram formula mass1 gram formula mass

18 grams18 grams

6.02 X 106.02 X 102323 molecules molecules

Moles and Formula Units

• Mole of a particular substance is 6.02 X 10 23 formula units of the substance because a molecule of a molecular substance and a formula unit of a molecular substance is the same thing.

Mole RelationshipsMole Relationships

3 Conversion Factors3 Conversion Factors

Conversion Factor 1 : The number of Conversion Factor 1 : The number of particles in 1 mole. Used for converting particles in 1 mole. Used for converting between number of particles and moles.between number of particles and moles.

6.02 X 106.02 X 102323 particles particles

1 mole 1 mole

Or invert numbersOr invert numbers

STPSTP

Standard temperature and Pressure such Standard temperature and Pressure such as 0as 0oo C and 1 Atmosphere or 760 mm of C and 1 Atmosphere or 760 mm of Hg or 101.3 KPaHg or 101.3 KPa

Conversion factor 2: The Molar volume at Conversion factor 2: The Molar volume at STP. Used for converting between STP. Used for converting between volume of a gas sample and moles.volume of a gas sample and moles.

22.4 22.4 dmdm33 1 Mole/ 1 Mole/

1 Mole or invert as 22.4 dm1 Mole or invert as 22.4 dm33

Conversion Factor 3: The gram atomic or Conversion Factor 3: The gram atomic or gram formula mass. Used for converting gram formula mass. Used for converting between mass in grams and moles.between mass in grams and moles.

Gram atomic or formula mass/Gram atomic or formula mass/

1 mole1 mole

Or invert that relationshipOr invert that relationship