## How to Balance A Chemical Reaction

Princess Jereza 3C
Posts: 46
Joined: Sat Jul 20, 2019 12:16 am

### How to Balance A Chemical Reaction

In the textbook, in example L.1 on F89, there was a step where a chemical reaction had to be balanced, which was Fe2O3 + CO -> Fe + CO2, and the balanced equation was Fe2O3 + 3CO -> 2Fe + 3CO2. I got stuck balancing it cause I got Fe2O3 + 2CO -> 2Fe + 2CO2, I knew something was wrong, but I did not know how to solve it. Can someone explain how the balanced equation came out to be Fe2O3 + 3CO ->2Fe + 3CO2? Thank you.

Siya Shah 1J
Posts: 50
Joined: Sat Aug 17, 2019 12:15 am

### Re: How to Balance A Chemical Reaction

Ok so this is how I'd approach it. I want to balance Fe first, so I add 2 in front of the product Fe to get Fe2O3 + CO >> 2Fe + CO2. Then, it seems like there are 4 O atoms on the reactants side and 2 on the products side, so it seems natural the 2 goes in front of the CO2. However, like you did, when you place a 2 in front of the CO, the oxygens are out of balance. At this point, you just sort of have to puzzle it out. Since you're likely not gonna add a stoichiometric in front of the Fe2CO3, and you have 3 oxygen atoms in that reactant, your stoichiometric coefficient in front of CO2 has to yield a number of oxygen atoms on the products side that is a multiple of 3. From there, the next step is just to change the 2 to a 3 in front of CO2, and when you add a 3 in front of CO to balance the carbon atoms, you see that the reaction is balanced. Hope this helps!

Karyn How 1J
Posts: 50
Joined: Thu Jul 25, 2019 12:16 am

### Re: How to Balance A Chemical Reaction

Hi,
so when you look at each molecule such as 2CO, make sure that you know that 2 is being applied to both carbon and oxygen. The reaction you wrote didn't work out due to the fact that 2 CO2 would mean that there are 2 carbons and 4 oxygens on the product side, however, on the reactant side, there are 2 carbons and 2 oxygens from 2CO and also an additional 3 more oxygens from Fe2O3.

When you balance equations, try to look at the element that has the least moles (in this case Fe). So first for Fe there would be 2 from reactant Fe2O3 and putting a 2 in front of Fe. Then I would try to balance the amount of oxygen since I kind of set Fe2O3 and work on carbon afterward.

William Francis 2E
Posts: 86
Joined: Wed Sep 18, 2019 12:20 am

### Re: How to Balance A Chemical Reaction

Fe2O3 + 2CO --> 2Fe + 2CO2 is balanced for iron and carbon but not oxygen. There are five oxygen units of oxygen on the left side of the equation but only four on the left. Since CO and CO2 are the only two compounds in the equation with carbon, they must have the same coefficient. Similarly, since, Fe2O3 and Fe are the only two compounds that contain iron, the coefficient of Fe must be twice that of Fe2O3. Also, you should note that no matter what coefficient is used for CO2, there will always be an even number of oxygen atoms in play. Here, the problem is that there are an odd number of oxygen atoms on the left side of the equation. From this point, you sort of need to guess and check to solve the puzzle and balance the chemical equation. For me, figuring out some logical statements that must be true speeds up the guessing and checking process to make sure each side of the equation has the same number of each type of atom. In conclusion, balancing chemical equations is always a good time.

Elizabeth_3F
Posts: 5
Joined: Fri Aug 02, 2019 12:16 am

### Re: How to Balance A Chemical Reaction

Remember when balancing equations, start with the least number of atoms so you won't get confused!

Emma Joy Schaetz 1E
Posts: 43
Joined: Wed Sep 18, 2019 12:16 am

### Re: How to Balance A Chemical Reaction

Elizabeth_3F wrote:Remember when balancing equations, start with the least number of atoms so you won't get confused!

Is this always true with balancing equations?

Justin Quan 4I
Posts: 94
Joined: Sat Sep 14, 2019 12:17 am

### Re: How to Balance A Chemical Reaction

Emma Joy Schaetz 1E wrote:
Elizabeth_3F wrote:Remember when balancing equations, start with the least number of atoms so you won't get confused!

Is this always true with balancing equations?

Yes, for the most part, start with the most complex molecule first, usually one that’s not H2O or O2, because water and oxygen are easier to balance.

Caitlin Ciardelli 3E
Posts: 44
Joined: Wed Sep 18, 2019 12:19 am