Posted by Cindy on .
25cm^3 of a gas containing only nitrogen and oxygen decomposed to form 25cm^3 of nitrogen and 50cm^3 of oxygen. All the volumes were measured at the same temperature and pressure. Write an equation for the reaction.

Chemistry 
DrBob222,
2*N_{x}O_{y} = xN2 + yO2
Using the coefficients in the balanced equation, convert cc N2 to cc NxOy and solve for x AND
convert cc O2 to cc NxOy and solve for y like this.
25cc N2*(2mols NxOy/x molN2) = 25 cc NxOy. Then
25*(2/x) = 25 and x = 50/25 = 2
For y,
50 cc O2*(2 mols NxOy/ymol O2) = 25 cc NxOy
Finally 50*2/y = 25 and y = 100/25 = 4
So x = 2 and y = 4 so NxOy must be N2O4. We can check that this way.
N2O4 ==> N2 + 2O2
25cc....25cc...50cc
Start with 25 cc N2 will give us 25 cc N2O4 and 50 cc O2.
Start with 50 cc O2 and we would expect 25 cc N2 and 25 cc N2O4.
N2O4 must be right.