Balancing Chem Equations

[·WídgêT·]

I'm going into AP Chemistry as a junior this year, and chem has always been one of my strongest subjects, but now I'm starting to think that was just because I wasn't being challenged enough. I always liked to balance equations because I was good at it, but now I'm running into tougher and tougher problems. Since I never really developed a surefire method of solving them, it's getting more and more difficult. I am working on such equations as we speak

Any tips on effective ways to balance chemical equations will be much appreciated

[Rypto]

If you get stuck on one, I can help. I'm fairly good at chemistry myself! 

[Goalie]

Sometimes using larger numbers helps more instead of smaller numbers.  let's say we have
_ Na + _ NaNO₃ → _ Na₂O + _N₂

we'll need at least 6 Na to balance it because the smallest common multiple of 2 and 3 is 6.  So any multiple of 6 Na will give us a good start at the problem.  the only problem is dividing it up between Na and NaNO₃.

This one will take a bit of critical thinking, but it is much easier when you figure out this least common multiple.

[Mrs.Booyah]

That is a very general comment that you posted.  When you are dealing with balancing chemical equations, you may or may not need to take into account whether the reaction even has the possibility of happening.  Some teachers throw those kinds of questions in there just to see if you paid attention in Chem 1.  Reactions may not have a chance of happening unless maybe temperature or pressure play a part along with the possible introduction of a catalyst.  When I use to balance reactions, I would always start with the more complex molecule.  Example:  in the reaction above, try to balance the sodium nitrate and the sodium oxide first and then the sodium solid and the nitrogen gas.  Balancing a chemical reaction also depends on the reaction itself, more directly, what kind of reaction (i.e. ox/redox, substitution, etc.) because you can complicate things by having to take into account oxidation numbers.  Most important: start with the most complex molecule and then finish balancing with the simple molecules or elements.  Hope this helps.

[BFM_Exodus]

A very good point Mrs Booyah. The simpler molecules and elements are always the best to finish with. It is much easier to finish balancing, say Oxygen or Hydrogen gas in an equation then a more complex molecule. Even water or carbon dioxide is far simpler the trying to balance many compounds.

I am not sure where you are in Chemistry compared to the Chemistry I do in my final year here in Australia, however I know that eventually you will get to the stage where you will be writing the equations yourself. You may even be expected to memorize some. Remembering how reactions take place with certain molecules present is a real factor. Recognizing Redox Reactions from Acid/Base, etc can also be very important and the greater your understanding of these will increase your efficiency in working with the equations. Each of these often come with their own set of rules for Reactant -> Product. Knowing these by heart and what to expect in questions can be your greatest asset.

Also be familiar with what you are studying. Often you will concentrate on specific molecules and/or an area of chemistry. School is good like that, so you can always be prepared. Even ask your teacher. And just remember that it isn't always the complicated equations and molecules that may be worth the majority of the marks. The questions that follow on and that are worth the most marks are often simple with a slight twist to try and confuse you. Good chemistry students are hopefully able to pick that out.

[·WídgêT·]

Your advice has helped a lot. The equations I was working on were just the basics because this was only a summer assignment to keep our brains working until school starts again. However I'm sure that we will eventually be learning about all that you explained. Goalie's comment can easily be used on the basics too, and Exodus just expanded on that for more complex situations. I'm definitely coming back to this topic during the school year if I'm still confused