Question

if you are given the equation 2NO(g)+o2(g)->2NO2 and you are given the volume of NO is 150mL. how do you find what the volume of O2 is required (at the same pressure and temperature)?

Answer 1

2NO(g) + O2(g) --> 2NO2(g)

When all gases are listed one can take a shortcut and use volume directly as mols.
volume NO = 150 mL
Convert NO to O2
150 mL NO x (1 mol O2/2 mols NO) = 150 x 1/2 = 75 mL O2 required.