Chem 1405 Mole and Chemical Formulas Notes

MOLE and CHEMICAL FORMULAS
Stoichiometry

How many grams of acid are needed to prepare 300 mL of a solution 2.0M ?

How much iron can be obtained from a 50 pounds of iron ore?
How many moles of oxygen are consumed during the combustion of ethane?

◦ STOICHIOMETRY : the study of the mass relations in chemistry.
◦ Mol – Grams

◦ Grams - mol

◦ Grams of reactants – grams of product

◦ Mol product – mol of reactant

The Mole –Chemist’s Dozen

Large items are count by units

◦ 1 dozen of eggs = 12 eggs

◦ 1 lb of rice = 16 oz of rice
How do you count particles that you don’t see?

A mole is Avogadro’s number of items

Chemists use the MOLE unit.

◦ Mole is a very large number

◦ Avogadro’s number: 6.022 x 1023

1 one mole of anything = 6.022 X 1023 of that same anything
1 mole of sand grains = 6.022 x 1023 sand grains

1 mole of marbles = 6.022 x 1023

1 mole of He atoms = 6.022 x 1023 He atoms

Example:
Calcium is the most abundant metal in the human body. A typical human body contains roughly 30
moles of calcium.

Determine

(a) the number of Ca atoms in 30.00 moles of calcium
(b) the number of moles of calcium in a sample containing 1.00 × 1020 Ca atoms.