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Jack Wilson Honors Chemistry Period 7
Gases
1. Pressure gas particles are in constant, rapid, random motion
and exert pressure as they collide with thewalls of their
containers.
*As pressure decreases, volume increases Boyles Law*As pressure
drops, temperature drops Gay-Lussacs Law*As temperature drops,
volume drops Charles Law
*As moles increase, volume increases Avogadros Law*Combine all
of these laws Combined Gas Law
1a. Boyles Law indirectly proportional P1V1 = P2V2
1b. Gay-Lussacs Law directly proportional P1T1 = P2T2
1c. Charles Law directly proportional V1/T1 = V2/T2
1d. Avogadros Law V/n1 = V2/n2
1e. Combined Gas Law P1V1/T1n1 = P2V2/T2n2
2. Kinetic Molecular Theory there are five steps
a. Gases are in constant, random motion
b. Space between atoms considered negligible
c. The energy for a sample of gas is considered constant
d. Attractive and repulsive forces are negligible
e. The kinetic energy of the molecule is proportional to the
temperature
3. Effusion gas escaping into a vacuum
3a. Rate of effusion the ration of effusion of a gas is
inversely proportional to the square root of its molarmass
*time1/time2 = rate2/rate1 = rootMW1/rootMW2
4. Real vs. Ideal Gas Law
4a. Real Gases kinetic molecular theory is for ideal gases. A
real gas is a gas that doesnt behave ideallyunder all conditions
(must take into account space between molecules and attractive and
repulsive foces)
*Rule: the bigger the gas and the closer it is to being a
liquid, the less ideal it is. Ex: CO2 less ideathan O2
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4b. Combine Laws PV = nRT aka The Ideal Gas Law
*R = universal gas constant*If atm R = 0.0821*If kPa R =
8.315*If mmHg R = 62.4
4c. Ideal Gas Law (see formula above)
*If gases follow the KMT, they are said to be ideal
gases*Although no ideal gases exist, the theory still provides a
good model to explain gas properties
4d. Some important formulas to memorize:
*MW = mRT/PV*MW = m/(PV/RT)*MW = DRT/P*MW = DV/n*D = MWP/RT
*D = MWn/V*D = m/(nRT/P)*D = mP/nRT*D = m/V*MW = m/n
5. Measuring Pressure with a Barometer
*A manometer is a devise used to measure the pressure of an
enclosed gas sample.
*Gas pressure = atmospheric pressure height
5a. Daltons Law of Partial Pressure
1) The total pressure exerted by a mixture of gases is the sum
of the individual pressure of each gas2) Each individual gas
behaves as if it were independent of the others
5b. Mole Fraction the ration of the number of moles of a given
component in a mixture to the total numberof moles in the
mixture
*X2 = n2/ntotal = P2/Ptotal
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