3. Scheffler
Gases
Variable volume and shape
Expand to occupy volume available
Volume, Pressure, Temperature,
and the number of moles present
are interrelated
Can be easily compressed
Exert pressure on whatever
surrounds them
Easily diffuse into one another
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4. Scheffler
Boyle’s Law
According to Boyle’s Law
the pressure and volume
of a gas are inversely
proportional at constant
pressure.
PV = constant.
P1V1 = P2V2
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5. Scheffler
Boyle’s Law
A graph of pressure and volume gives an inverse
function
A graph of pressure and the reciprocal of volume
gives a straight line
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6. Scheffler
Charles’ Law
According to Charles’ Law the volume of a
gas is proportional to the Kelvin temperature
as long as the pressure is constant
V = kT
V1
=
T1
V2
T2
Note: The temperature
for gas laws must
always be expressed
in Kelvin where Kelvin
= o
C +273.15 (or 273
to 3 significant digits)
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7. Scheffler
Charles’ Law
A graph of temperature and volume yields a straight line.
Where this line crosses the x axis (x intercept) is defined
as absolute zero
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8. Scheffler
The Combined Gas Law
1. If the amount of the gas is constant, then
Boyle’s Charles’ and Gay-Lussac’s Laws
can be combined into one relationship
2. P1 V1 = P2 V2
T2
T1
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9. Scheffler
Advogadro’s Law
Equal volumes of a gas under the same temperature
and pressure contain the same number of particles.
If the temperature and pressure are constant the
volume of a gas is proportional to the number of
moles of gas present
V = constant * n
where n is the number of moles of gas
V/n = constant
V1/n1 = constant = V2 /n2
V1/n1 = V2 /n2
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