Today’s Lesson Pre-requisites

to get into the University of Stoichiometry:

ü Elements

ü Compounds (nomenclature)

ü Formula

ü gà mol

ü Chemical reactions  (reactants  à products )

ü Balancing Equations

STOICHIOMETRY 101

- that the amounts of reactants and products can be predicted using balanced equations, coefficients, mol ratios and molar masses.

- Using the balanced reaction coefficients to calculate:

a.  % Yields

b.  Limiting Reactant

c.  Excess (X-S)Understanding

d.  % Purity

Text ch.5 page 154 Q.#1-6

                              Ca _(s)   +  2 H₂O   à  Ca(OH)_{2 (aq)}  +   H_{2 (g)}

MASS     25.0 g 22.5               0.623 x 74.1 g/mol = 46.2 g    1.25 g                         ?

n (mol)   0.623 mol 1.25 mol 0.623         mol   0.623 mol

           25.0 g [ 1mol   ]    = .623 mol

                        40.1 g

Given the green, do the mol conversion (red) next.  .. then do the mol line next (red) using mol ratios.

Do the mol line first,                 

To get the other unknown mol use  MOLE RATIOS !

 (from the coefficients in the balanced equation)

0.625 mol Ca [ 2   mol H₂O   ]   =   1.25 mol H₂O       x [18.0 g ]  

                     [  1  mol Ca        ]                                                               1 mol

                                                                                                =  22.5  g