Question

I'm taking chemistry with FLVS and the course does not tell me how to balance chemical equations - just say do it. Can anyone explain it to me? Here's an example of a balance equation: 3H2+N2 = N2H3
It say you can change the coefficient but not the subscripts but it looks like it changed both.. HELP.

Answer 1

Well the key here is that the reaction itself is described by the subscripts. You have to change the coefficients. This probably makes no sense to you, but hopefully it does in a second.

Imagine as though what you're doing is playing around with legos. Whatever is on the left is exactly the same number of legos as on the right. The difference is, on either side of the chemical equation you have built separate things with the pieces:

So here's a fake example with squares and rectangles to show what I mean: \[\Large 2 SquareRectangle \rightarrow 1Square_2+1Rectangle_2\] So you can see the subscripts are telling you how many are in a single connected bit, and what's attached is changing and all that. So there's not exactly a specific algorithm to do this, but you really don't need to after you see what is going on. The main idea is that chemical reactions obey conservation of mass. Just a fancy way of saying that you can't destroy matter, only rearrange it.