The Mole and Chemical Quantities The Mole and Chemical Quantities How Many Ways Can We View the Mole?

The Mole A mole describes a chemical quantity…it’s just a number!!! A mole describes a chemical quantity…it’s just a number!!! a pair = a pair = 2 (shoes) 2 (shoes) a dozen = a dozen = 12 (eggs) 12 (eggs) a score = a score = 20 (years) 20 (years) 1 mole = 6.02 x units = Avogadro’s # 1 mole = 6.02 x units = Avogadro’s # you can have a ‘mole’ of anything…shoes, cars, people etc… you can have a ‘mole’ of anything…shoes, cars, people etc…

Just How Big is a Mole? If you had Avogadro's number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles.

Just How Big is a Mole? If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole.

Just How Big is a Mole? Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles.

The Mole can be… A number of objects: 1 mole = 6.02 x representative particles, usually atoms, molecules or ionic formula units. Because atoms, molecules and ions are exceedingly small, we need a unit of measurement to represent a specific number of particles A mass of substance in grams: –Gram atomic mass –Gram molecular mass Molar Mass (generally) –Gram formula mass

Representative Particles The representative particles can be atoms, molecules or formula units (ions) For most elements the representative particle is the atom Seven elements exist as diatomic molecules, thus their representative particle is the molecule, BrINClHOF For molecular compounds the representative particle is the molecule For ionic compounds the representative particle is the formula unit

Gram Atomic Mass Equivalent to the average mass of an atom on the periodic table rounded to the hundredths place. 1 mol = g-atomic-mass (periodic table) C = g/mole O = g/mole H = 1.01 g/mole Mg = 24.31g/mole

Mole Conversions Mass to moles And Moles to mass

Molecular & Formula Mass To calculate… 1.Using the periodic table, find the mass of each element in a compound. 2.Multiply the mass of each element by its subscript in the compound. 3.Add all of the masses of each element together. 4.This is the molar mass of this compound. Gram-formula-mass Fe 2 O 3 2 Fe = 2 x 55.6 g = g 2 Fe = 2 x 55.6 g = g 3 O = 3 x 16.0 g = 48.0 g 3 O = 3 x 16.0 g = 48.0 g g/mol g/mol

Converting to and from moles Requires the following mole equalities: 1 mol = g-formula-mass (periodic table) Each equality can be written as a set of two conversion factors. They are: or

Mole-Mass Conversions Example: What is the mass of 5.00 moles of Fe 2 O 3 ? 5.00 moles Fe 2 O 3 * = 796 grams Fe 2 O 3

Mass- Mole Conversions Example: How many moles in 28 grams of CO 2 ? Gram-formula-mass of CO 2 1 C = 1 x 12.0 g = 12.0 g 2 O = 2 x 16.0 g = 32.0 g 44.0 g/mol 28 g CO 2 * = 0.64 moles CO 2

Mole Conversions Representative Particles to moles And Moles to Representative Particles

Converting to and from moles Requires the following mole equalities: 1 mole = 6.02 x representative particles Each equality can be written as a set of two conversion factors. They are: or

Particle- Mole Conversions Example: How many moles are in 2.61 x molecules of CO 2 ? 2.61 x molecules CO 2 * = 4.34 x moles CO 2

Mole-Particle Conversions Example: How many formula units are in 5 moles of Fe(NO 3 ) 2 ? 5 mol Fe(NO 3 ) 2 * = 3.01 x formula units Fe(NO 3 ) 2

Mole Conversions Representative Particles to Mass And Mass to Representative Particles

Particle- Mass Conversions Example: How many grams are in 2.61 x molecules of CO 2 ? 2.61 x molecules CO 2 * * = 1.91 x g CO 2

Mass-Particle Conversions Example: How formula units are in 5.00 g of Fe(NO 3 ) 2 ? 5.00 g Fe(NO 3 ) 2 * * = 1.67x formula units Fe(NO 3 ) 2