Another Way to Balance

[kendallbottrell]

Is there another way to balance equations that doesn't involve just "guess and check"? Maybe something that is more systematic?

[Endri Dis 1J]

When balancing equations I tend to use my intuition than any systematic method but there is a long mathematical method that includes setting up and solving a system of linear equations, so guess and check would be the quickest way to balance the equations.

[Caroline Crotty 1D]

Guess and check is the best way to solve these problems, but there are ways to make it easier. You can start by taking the most complex part and trying to balance that first and work your way down to single elements. In a combustion analysis it is generally easiest to start with carbon then hydrogen then oxygen.

[Miya Lopez 1I]

This might still be guessing and checking, but when I balance equations I write down each element in a column. Then, I write how many there are on the left side of the equation to the left of the element & how many there are on the right side of the equation to the right of the element. Then when I add a coefficient, I recount and cross out the number next to the element and write the new one. That just helps me see that I'm balancing everything correctly.

[Vienna Cimetta 1L]

It's always easiest to start with the element that occurs the least in the reaction, moving your way to the elements that occur the most. Also,if an element stands on it's own leave it until the last, because it is an easy fix to just had a coefficient in front that will balance out the element on either sides. Often elements like H or O will be present many times and should be left until later to balance.

[Hussein Saleh 1L]

Sadly Guess and Check is your best bet when it comes to solving those problems. It may not be quick at times but it gets the job done

[Garrett Dahn 1I]

So since high school I've just been using guess and check, or at least some variation of that, and there would always be a couple equations that would give me so much grief to check. My TA, however, recently described a different way to balance chemical equations that seems to be a little more surefire and is pretty simple.

So if you've got: __KClO3 + __C6H1206 --> __KCl + __CO2 + __H20

You can guess and check, or, you can set up a algebraic system of equations. Assign a variable to each blank:
(a) KClO3 + (b) C6H1206 --> (c) KCl + (d) CO2 + (e)H20

Then write an equation for each element in the chemical equation based on the number of particles of that element in each part of the equation. For example, there is one Potassium (K) for the (a) variable...

K: (a x 1) + (b x 0) = (c x 1) + (d x 0) + (e x 0)
Cl: (a x 1) + (b x 0) = (c x 1) + (d x 0) + (e x 0)
O: (a x 3) + (b x 6) = (c x 0) + (d x 2) + (e x 1)
C: (a x 0) + (b x 6) = (c x 0) + (d x 1) + (e x 0)
H: (a x 0) + (b x 12) = (c x 0) + (d x 0) + (e x 2)

Which becomes...

K: a = c
Cl: a = c
O: 3a + 6b = 2d + e
C: 6b = d
H: 6b = e

Then, you have to make an assumption. Usually I just assume a = 1, then just solve for your variables as you would in any algebra class. You should get...

a = 1
b = 1/4
c = 1
d = 6/4
e = 6/4

The last step is just to make these whole numbers, since you can't have fractions of elements in a chemical equation. So, for this specific problem, multiply every variable value by 4.

a = 4
b = 1
c = 4
d = 6
e = 6

Then just put these values in where you put the variables (a,b,c...) and you've got yourself a balanced chemical equation! I've found this process to take more time than guess-and-check, but especially for the more challenging equations, this one requires a little less hard thinking and it seems to almost always give the correct answer.

[Mjay 1F]

This might still be guessing and checking, but when I balance equations I write down each element in a column. Then, I write how many there are on the left side of the equation to the left of the element & how many there are on the right side of the equation to the right of the element. Then when I add a coefficient, I recount and cross out the number next to the element and write the new one. That just helps me see that I'm balancing everything correctly.

I always write down the column when balancing equations and I really find it effective.