Another Way to Balance
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 Joined: Fri Apr 06, 2018 11:02 am
Another Way to Balance
Is there another way to balance equations that doesn't involve just "guess and check"? Maybe something that is more systematic?

 Posts: 33
 Joined: Fri Apr 06, 2018 11:02 am
Re: Another Way to Balance
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.

 Posts: 32
 Joined: Fri Apr 06, 2018 11:02 am
Re: Another Way to Balance
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.

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Re: Another Way to Balance
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.

 Posts: 31
 Joined: Thu Feb 01, 2018 3:01 am
Re: Another Way to Balance
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.

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Re: Another Way to Balance
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

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Re: Another Way to Balance
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 guessandcheck, 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.
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 guessandcheck, 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.
Re: Another Way to Balance
Miya Lopez 1L wrote: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.
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