Question

What is the coefficient for oxygen when the following equation is balanced? NH3( g) + O2( g) ® NO2( g) + H2O( g)

Answer 1

What do you think it is?

Answer 2

@tyrion

Answer 3

balancing equations requires a bit of trial and error. as a general rule of thumb, you'll want to start with more "complicated" compounds (with more atoms) before simpler compounds. so in this case, you'd balance oxygen last, and start with one of the other compounds.

Let's start with NH3. left side has 1 N, right side has 1 N. good so far. but the left side only has 3 H in NH3 while the left side has 2 H in H2O.

so we could balance out the H's by changing the coefficients like so:

2NH3( g) + O2( g) ® NO2( g) + 3H2O( g)

which gives us 6 H on each side. however, you'll notice that the N's have now become unbalanced. so you'll also need to balance out the N's again by adding a 2 in front of the NO2.

repeat this logic until everything is balanced. like I said before, you'll need to play around, but I'll help you if you get stuck.