alight+balancing

=Balancing=

Introduction
Okay, balancing may seem complicated at first, but ill break it down now into easy steps. Balancing just means making a reaction stable. Of course when i say the reaction, i mean both sides, that means both the reactants (left) and the products(right). This means knowning how to first make a balances molecule before you can even try to make a balanced equation.

IMPORTANT:
We use Subscripts to balance compounds, and from there we use COEFFICIENTS to balance equations. once we have a balanced compound you cannot change the subscripts, on the coefficients!

Balancing a Molecule
A balanced molecule will be neutral (most of the time) having their valence electrons equaling either 0 or 8 (2 in the case of hydrogen).

We see this in H20, the equation for water.

this is water unbalanced: HO

H has a one valence electron, and wants to go to either 0 or 2.

O has 6 and wants to go to either 0 or 8.

6 is closer to eight, so we will say it wants to gain two electrons.

this will make its charge -2.

so we put the superscript -2 above O.

HO(-2)

Since O is going to gain two electrons from the hydrogen (because O is more electronegative, our last chapter) that means that it wants two electrons from the hydrogen. But the hydrogen only has one electron to give! So the O takes two hydrogens.

meaning it will take 2 H's to satisfy the O's.

H2(+2)O(-2)

an easier way of doing this is to see that we can just do a switcheroo.

if O has a charge of -2...

hydrogen must have a charge of +1....

H(+1)O(-2)

just switch the superscripts to subscripts

H2O

and your molecule is balanced!

Sentences?
yes not all equations come in nice neatly packaged element and numeral form right way. in fact, its quite common to see them in words instead of letters. so just in case you ever run across these just look at the following sentence.

Hydrogen and oxygen react to form hydrogen oxide.

..... what does that mean?

well lets isolate things one at a time.


 * Hydrogen** //and// **oxygen** __react to form__ **hydrogen oxide**

okays these two elements are the basic foundations of all worded reaction sentences.

in bold we have the elements and/or compounds of the sentence.

underlined is the wording, this is important to find out which way the arrow is going.

lets subsititute in letters for the elements, and just simplify and for a + symbol.

H + O **react to form** HO.

now were only left with "react to form". this just implies that H + O are reacting with one anouther to form HO. we can substitute an arrow for this piece of the sentence.

H + O --> HO

Done! its now an equation... or is it?

HO isnt right... oh, its not balanced! its H2O!

H + O --> H20

Balancing an Equation
Okay, so we know how to balance a molecule and convert a sentence into an equation.

Lets bring back our friend water.

H2O.

how do we get this compound of hydrogens and oxygens? well we need to write an equation for it.

H + O --> H2O

well, theres a special rule for H's and O's. For the most part all elements will just be alone with a subscript 1 thought to be implied, assuming the roll of you have one of these elements. But for certain elements (diatomic) they are only stable when isolated when they are in pairs. Both H and O are diatomic.

so we plug in the values for them....

H2 + O2 --> H20

but this isnt right, we need the same number of atoms of each element on both sides.


 * (element) || Reactants || Products ||
 * Hydrogen || 2 || 2 ||
 * Oxygen || 2 || 1 ||

clearly we do not have the right amounts on both sides yet.

2H2 + O2 --> 2H20


 * (element) || Reactants || Products ||
 * Hydrogen || 4 || 4 ||
 * Oxygen || 2 || 2 ||

However if we multiply the water molecule and hydrogen by two, we have the same number of both elements on either side of the equation and it is balanced. this is what is key, and if you need to make charts like these when balancing for the harder equations.

Now your ready to take on the Five Kinds of Chemical Reactions