today I'd like to talk a little bit about
stoichiometry and gas stoichiometry
really is just as simple as any other type a stoichiometry
it works almost exactly like every other form of stoichiometry
one thing I'd like to discuss before we begin the actual stoichiometry has
to do with the concept that's called
Avogadro's law and Avogadro's law is actually used
to derive the following relationship: and it says that
that a gas at standard temperature and pressure
will occupy 22.4 liters
for every mole of that gas that's present doesn't matter what gas
all gases would occupy this same volume
the difference in the gases would be the mass of the gases that would occupy
that quantity
because of the gas density so I wanted to point that out to you that's a factor
that
that comes through a lot of times when we were relating
volume of gases to moles at STP
the next concept I'd like to talk about briefly is Gay Lassac's law
Gay Lussac's law says that
at a given temperature and pressure
the volumes of gases that react with each other
can be expressed in ratios of small whole numbers
and what this means essentially is that
we've always stressed to you the importance
of balanced equations and the balanced equations can be used to predict
the volume of gases that will be needed in a reaction
if we balance this reaction
we find that we would have 3 hydrogens
plus a nitrogen giving
2 ammonias
when we do this process we can state it another way we can say
that three moles of hydrogen will react with one mole of nitrogen
to form two moles of ammonia that's a second way that we can say this
according to Gay Lussac's law we can state take another step
and we can say that if these gases are at standard temperature and pressure
that 3 liters
of hydrogen
will react with one liter
of nitrogen
to produce two liters
of
ammonia
once again the reaction has and this
law has very practical terms
let's think about this a minute if we combine 3 liters of
hydrogen and 2 liters of nitrogen
that's four liters that would also be
in terms of moles it would be the same
it would be a certain number of moles wouldn't
we are adding four liters of reactants we're getting
2 liters of product out
so my question would be what's gonna happen to the pressure
in the reactor as this takes place obviously based on the fact that
that you're losing volume
your going to also be decreasing your pressure as well
and that's a practical application for people that are building reactors