answer and explanation
the balanced chemical reaction for the formation of nitrogen dioxie is
2NO + O₂ → 2NO₂
and so at STP the number of mols of nitrogen dioxide in 4.50L would be
PV = nRT
n = PV/RT
= (1atmx 4.50L) / (8.314 x 273.15K
= 4.50/2270.97
= 0.00204 mols
0.00204 mols of nitrogen dioxide would have been formed from the reaction.
we know from the balance reaction that 1 mol of oxygen forms 2 mols of nitrogen dioxide and so the mols of oxygen that were present would be
1/2 x0.00204 = 0.00102 mols
we know that 1 mol of a gas occupies a volume of 22.4L at STP and so
0.00102 mols of oxygen would have a volume of
0.0102 mols x 22.4 L/mol
= 0.0228L
0.0228L of oxygen would be needed
