Stoichiometric Determination:
Empirical Formula of Copper Chloride


Empirical Formula: the simplest whole-number ratio in which different kinds of atoms combine to form a compound (atoms combining as single, distinct units). For example,
nameEmpirical FormulaMolecular Formula
aluminum chlorideAlCl3AlCl3
For ionic compounds: Compound formula is the same as the empirical formula. The compound formula defines the formula unit, the simplest whole-number ratio of positive and negative ions giving an electrically neutral unit.

Empirical Formulas and mol: The empirical formula is the simplest whole-number ratio of numbers of mols of atoms in one mol of a compound. The mole (mol) is that quantity of matter possessing a mass equal to the formula weight expressed grams. For example:

Cu (a monatomic element)H2OAl2O3
Atomic Wt.: 63.546Formula Wt.: 18.016Formula Wt.: 102.
Mass of 1 mol = 63.546 gMass of 1 mol = 18.016 gMass of 1 mol = 102. g
63.546 g Cu/mol Cu18.016 g H2O/mol H2O102. g Al2O3/mol Al2O3
Empirical formula of Copper Chloride: CuxCly
If the compound is made of ... then ... Cl- ions are neededand the formula would be ...
Cu1+ and Cl1-1CuCl
Cu2+ and Cl1-2CuCl2
Cu3+ and Cl1-3CuCl3


You may work in pairs if you wish.

Producing solid Cu from a Cu(II) solution by reaction with Zn.

CuxCly (aq) + Zn (s) ---> ZnCl2 (aq) + Cu (s)

Removing water from the solid Cu


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