Answer to Question #133165 in General Chemistry for mike

Question

Butane, C4H10, and hydrogen gas are both used as fuels. The molecular mass of butane is 29 times greater than that of hydrogen and the volume of the molecules is also much larger. How is it possible for a mole of the larger butane molecules in the gaseous state at STP to occupy the same volume as a mole of H2?

Answer 1

Equal volumes of gases contain the same number of particles at the same conditions of temperature and pressure. This concept was discover by Avogadro who stated that at the same conditions of temperature and pressure, one mole of any gas occupies a particular volume. Specifically, one mole of any gas occupies 22.4 liters at standard temperature and pressure. Therefore, much as butane has larger and heavier molecules than hydrogen, one mole of each occupies 22.4 L at S.T.P.