Can someone please make me understand how balancing equations works?

Question

I can't seem to understand it. For example V2O5 + HCl ---> VOCl3 + H2O
....what the hell is that suppose to mean, I don't get how I can solve it.
I'd be really if someone would kindly explain it to me and provide examples.
thanks

Answer 1

This is just like solving and simplifying equations in algebra -- you want the left side and the right side to be equal. In chemistry, you want the quantity of each different atom to be the same on both sides of the equation. Look at your example:

V2O5 + HCl ===> VOCl3 + H2O

On the left side there are two Vanadium (V), five Oxygen, one Hydrogen, and one Chlorine; on the right you have one Vanadium, two Oxygen, three Chlorine, and two Hydrogen. So I'm going to have to adjust the number of molecules on each side until the quantities of atoms on each side are the same.

Let's start by assuming that the number of Vanadium atoms will remain constant, and try adjusting the other atoms to balance out. V2O5 reacts to make 2 VOCl3; now we need to add in the number of HCl and H2O to make the sides equal out.

If I make 2 VOCl3, then I will need a minimum of 6 chlorine atoms, which means 6 HCl on the left side, so:

V2O5 + 6 HCl ===> 2 VOCl3 + ?? H2O

I also have five oxygens on the left, and only use up two in the VOCl3, so that means I must have at least 3 H2O, thus:

V2O5 + 6 HCl ===> 2 VOCl3 + 3 H2O

Now, does that have equal quantities of atoms on each side?
on the left: 2 V, 5 O, 6 H, and 6 Cl
on the right: 2 V, 2 + 3 = 5 O, 2 x 3 = 6 Cl, 3 x 2 = 6 H

Since they are equal on both sides, this is now a balanced equation!

V2O5 + 6 HCl ===> 2 VOCl3 + 3 H2O

Try a few more on your own and see if that process helps.

Answer 2

All right, first things first. Let's make sure you understand what a chemical equation is: It's a statement of the chemicals that participate in a chemical reaction, and of the ratios in which they react. Chemical equations need to be balanced because without it, the equation can't be used to make predictions about how much of a certain reactant will be needed to produce X grams of a certain product. In other words, you can't do stoichiometry without a balanced equation.

Now...let's balance this bad boy. In order to balance an equation, you need to keep a running tally of how many atoms of each kind appear on either side. Basically, you're done balancing the equation when the numbers match up. In other words, if you've got 15 oxygen atoms on the left side (the reactant side), then you have to have 15 oxygen atoms on the right side (the product side). Think of it as your own personal way of enforcing the Law of Conservation of Mass.

Let's do a quick head count of the different kinds of atoms, so we know what we're working with:

V2O5 + HCl --> VOCl3 + H2O

Okay, on the left, you've got 2 vanadium atoms (V), 5 oxygen atoms (O), 1 hydrogen atom (H), and 1 chlorine atom (Cl). On the right, you have 1 vanadium, 3 chlorines, 2 hydrogens, and 2 oxygens (1 in VOCl3, and 1 in H2O). Obviously we have some work to do.

A couple of pieces of advice before we go any further: You can't change the chemical formulas. You can only add coefficients. Coefficients multiply ALL of the atoms in a chemical compound, so use them carefully. Also, I usually save the hydrogen atoms for last, unless it's unavoidable to balance them before everything else. In most cases, once you've balanced all the other atoms, the hydrogen atoms will already be balanced.

I have 2 vanadium atoms on the left, but only one on the right. I can solve this by multiplying VOCl3 by 2. The equation becomes:

V2O5 + HCl --> 2 VOCl3 + H2O

Let's do another head count:
REACTANT SIDE: 2 V, 5 O, 1 H, 1 Cl
PRODUCT SIDE: 2 V, 3 O, 6 Cl, 2 H

The chlorines can easily be balanced by multiplying the HCl by 6:

V2O5 + 6 HCl --> 2VOCl3 + H2O

REACTANT SIDE: 2 V, 5 O, 6 H, 6 Cl
PRODUCT SIDE: 2 V, 3 O, 6 Cl, 2 H

Remember when I told you to save the hydrogens for last? Well, I'm about the break that rule, but here's why...oxygen is present in 2 compounds on the right. It's tougher to balance an element when it's present twice on one side, so we'll go with the hydrogen for now. Since there are two hydrogen atoms in H2O, we can multiply H2O by 3 to get 6:

V2O5 + 6 HCl --> 2 VOCl3 + 3 H2O

REACTANT SIDE: 2 V, 5 O, 6 H, 6 Cl
PRODUCT SIDE: 2 V, 5 O, 6 Cl, 6 H

And all is right with the world.

Now, that might seem kinda confusing, but it's a method...a means of solving a problem. It takes time and, more importantly, practice to get good at it. Keep your chin up. You'll get it!

Answer 3

Okay. When you are balancing an equation, your goal is to get the same number of each element on both sides of the equal sign. The smaller numbers next to elements are called subscripts, and normal sized ones are called coefficients. Example: in 3H2O, 2 is the subscript and 3 is the coefficient. When balancing, youre not allowed to change subscripts; you must change the coefficients to make the number of elements on each side the same. A simple example would look something like this: HCl >>> H2 + Cl2 So, you have 1 H and 1 Cl on the left, and 2 of each on the right. To make it balanced, you would put a 2 in front of the HCl on the left: 2HCl >>> H2 Cl2. So, for the equation you listed: V2O5 + HCl >>> VOCl3 + H2O There is 2 V, 5 O, 1 H, and 1 Cl on the left, and 1 V, 2 O, 3 Cl, and 2 H on the right. To balance it, you have to change the coefficients. The balanced eq looks like this: (V2O5) + 6(HCl) >>> 2(VOCl3) + 3(H2O). This is because this makes every element equal on the left and the right: 2 V, 5 O, 6 H and 6 Cl on each side.

Answer 4

Basically, what you wanna do is get an equal amount of each element on both sides of the equation. So you start off by listing how many of each element you have on both (to the right of the arrow and to the left of the arrow) sides:

Right: Left:
V - 2 1
O - 5 1
H - 1 2
Cl - 1 3

Add coefficients. When you add a coefficient, that coefficient will multiply by any subscripted number, increasing the number of that element. It's confusing but basically, what you should get is:

V2O5 + 6HCl ----> 2VOCl3 + 3H20

You can Google the basics for balancing equations; they have a lotta good sites for it. Hope I did that correctly.