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→Balancing Equations
: You may know the [[Chemical Formula|chemical formulae]] of the [[reactant]]s and [[product]]s but not know the number of each [[chemical]] needed. For that you must '''balance the equation'''.
: To '''balance and equation''' you need the same number of each type of [[atom]] on the left as you do on the right.
Lithium + Fluorine → Lithium Fluoride
: _Li + _F<sub>2</sub> → _LiF
: Reactants = Products
: 1Li ≠ 2Li
: 2F = 2F
There are now too many [[Lithium atoms ]] [[atom]]s in the products [[product]]s so we need 2 in the reactants[[reactant]]s.
: 2Li + _F<sub>2</sub> → 2LiF
: 2F = 2F
This equation is balanced: 2Li + F<sub>2</sub> → 2LiF
Aluminium + Chlorine → Aluminium Chloride
: _Al + _Cl<sub>2</sub> → _AlCl<sub>3</sub>
: Reactants = Products
: 1Al = 1Al
: 2Cl ≠ 3Cl
We need the same number of [[Chlorine]] [[atom]]s on both sides. To do that we can find the [[Lowest Common Multiple]]. In this case it is 6, so we times the left 2 [[Chlorine]]s by 3 and the right 3 [[Chlorine]]s by 2.
: _Al + 3Cl<sub>2</sub> → 2AlCl<sub>3</sub>
: Reactants = Products
: 1Al ≠ 2Al
: 6Cl = 6Cl
There are now too many [[Aluminium]] [[atom]]s on the right, so we need to multiply the left [[Aluminium]] by 2.
: 2Al + 3Cl<sub>2</sub> → 2AlCl<sub>3</sub>
: Reactants = Products
: 2Al = 2Al
: 6Cl = 6Cl
This equation is now balanced: 2Al + 3Cl<sub>2</sub> → 2AlCl<sub>3</sub>
Aluminium + Oxygen → Aluminium Oxide
: _Al + _O<sub>2</sub> → _Al<sub>2</sub>O<sub>3</sub>
: Reactants = Products
: 1Al ≠ 2Al
: 2O ≠ 3O
We need the same number of [[Oxygen]] [[atom]]s on both sides. To do that we can find the [[Lowest Common Multiple]]. In this case it is 6, so we times the left 2 [[Oxygen]]s by 3 and the right 3 [[Oxygen]]s by 2.
: _Al + 3O<sub>2</sub> → 2Al<sub>2</sub>O<sub>3</sub>
: Reactants = Products
: 1Al ≠ 4Al
: 6O = 6O
The [[Oxygen]] [[atom]]s are now balanced but the [[Aluminium]] [[atom]]s are not. We need 4 times as many [[Aluminium]] [[atom]]s on the left.
: 4Al + 3O<sub>2</sub> → 2Al<sub>2</sub>O<sub>3</sub>
: Reactants = Products
: 4Al = 4Al
: 6O = 6O
This equation is now balanced: 4Al + 3O<sub>2</sub> → 2Al<sub>2</sub>O<sub>3</sub>