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Here we are going to use the Clausius-Clapeyron equation to
estimate the heat of vaporization
of a pure component given the following vapor pressure or saturation pressure
data
we have at two temperatures
were given the saturation pressures for these two temperatures
so the saturation pressure in kilapascals
and so now we're going to use the
Clausius-Clapeyron equation
so the left side is the natural log of the saturation pressures
evaluated at temperature T2
and divided by the saturation pressure
at temperature
T1.
R
is the gas constant
and delta H is the heat of vaporization
that we are trying to determine.
and so we are going to substitute the values in where we want to keep in mind
these values here
must be absolute temperatures
so i substituted in the values here
300 being temperature T2
and 260
being temperature T1 over here. And the corresponding saturation pressures
so i can do the calculations. So I've substituted in
the values
reduced it to the heat of vaporization equals 4460 times the
gas constant
which means 4460
times
8.314 Joules per mol Kelvin
So notice here the units of
this term
is one over the temperature and so that cancels the kelvin term here
so the heat of vaporization
is going to be in Joules per mole
and so our final answer then
really can only justify two significant figures
considering the significant figures are
original data