CHEM 219 Exam # 3 with complete
solutions
Avogadro's Law - ANSWER- equal volumes of gases at the same temperature and
pressure contain equal numbers of molecules
Boyle's Law - ANSWER- Boyle's Law states that at constant temperature and
moles, pressure and volume are inversely proportional.
Mathematically this is written as: PV = PV
Charles' Law - ANSWER- the law that states that for a fixed amount of gas at a
constant pressure, the volume of the gas increases as the temperature of the gas
increases and the volume of the gas decreases as the temperature of the gas
decreases
Gay-Lussac's Law - ANSWER- the pressure of a gas is directly proportional to the
Kelvin temperature if the volume is constant
Combined Gas Law - ANSWER- the relationship between the pressure, volume,
and temperature of a fixed amount of gas
Ideal Gas Law - ANSWER- PV=nRT
R=.0821
If 5.00 g of Gas A and 5.00 g of Gas B are mixed in the same container, and the
partial pressure of Gas B is determined to be twice that of Gas A, what do we
know about the gases? - ANSWER- If Gas A has half the partial pressure of Gas
B, this indicates that there are fewer moles of it at the same mass, and therefore
Gas A has twice the molar mass of Gas B
mol fraction and partial pressure - ANSWER- the formula for both
, Amonton's Law - ANSWER- if the volume of a gas is held constant, increasing the
temperature of the gas increases its pressure.
Boyle's Law
in terms of KE - ANSWER- Volume decreased, wall area decreased = increased
pressure
Avagadro's Law
in terms of KE - ANSWER- Container pressure constant, more gas molecules
added = increased volume
Dalton's Law - ANSWER- The total pressure of a mixture of gases is the sum of
the individual pressures (Ptotal=P1+P2+P3...)
The kinetic energy (KE) of a particle of mass (m) and speed (u) is given by -
ANSWER- KE = 1/2 mu^2
The KE avg of a collection of gas molecules is also directly proportional to the
temperature of the gas and may be described by the equation - ANSWER- KEavg
= 3/2 RT
Kinetic Molecular Theory - ANSWER- The Kinetic Molecular Theory states:
⋅⋅There is no attraction between the gas particles.
⋅⋅The volume available to the gas particles is equal to the volume of
the container.
⋅⋅The measured pressure is from collisions of the gas particles with
the walls of the container.
⋅⋅The average kinetic energy is proportional to the temperature of
the system.
Which of the following gas samples have the greatest average molecular speed at
25°C? - ANSWER- Speed of individual gas molecules is inversely proportional to
the molar mass. CH₄ has a molar mass of just over 16 g/mol and is the smallest of
the gases listed. Therefore it has the fastest molecular speed.
What is the difference between effusion and diffusion? - ANSWER- Effusion is
through a pinhole, and diffusion is through open space.
solutions
Avogadro's Law - ANSWER- equal volumes of gases at the same temperature and
pressure contain equal numbers of molecules
Boyle's Law - ANSWER- Boyle's Law states that at constant temperature and
moles, pressure and volume are inversely proportional.
Mathematically this is written as: PV = PV
Charles' Law - ANSWER- the law that states that for a fixed amount of gas at a
constant pressure, the volume of the gas increases as the temperature of the gas
increases and the volume of the gas decreases as the temperature of the gas
decreases
Gay-Lussac's Law - ANSWER- the pressure of a gas is directly proportional to the
Kelvin temperature if the volume is constant
Combined Gas Law - ANSWER- the relationship between the pressure, volume,
and temperature of a fixed amount of gas
Ideal Gas Law - ANSWER- PV=nRT
R=.0821
If 5.00 g of Gas A and 5.00 g of Gas B are mixed in the same container, and the
partial pressure of Gas B is determined to be twice that of Gas A, what do we
know about the gases? - ANSWER- If Gas A has half the partial pressure of Gas
B, this indicates that there are fewer moles of it at the same mass, and therefore
Gas A has twice the molar mass of Gas B
mol fraction and partial pressure - ANSWER- the formula for both
, Amonton's Law - ANSWER- if the volume of a gas is held constant, increasing the
temperature of the gas increases its pressure.
Boyle's Law
in terms of KE - ANSWER- Volume decreased, wall area decreased = increased
pressure
Avagadro's Law
in terms of KE - ANSWER- Container pressure constant, more gas molecules
added = increased volume
Dalton's Law - ANSWER- The total pressure of a mixture of gases is the sum of
the individual pressures (Ptotal=P1+P2+P3...)
The kinetic energy (KE) of a particle of mass (m) and speed (u) is given by -
ANSWER- KE = 1/2 mu^2
The KE avg of a collection of gas molecules is also directly proportional to the
temperature of the gas and may be described by the equation - ANSWER- KEavg
= 3/2 RT
Kinetic Molecular Theory - ANSWER- The Kinetic Molecular Theory states:
⋅⋅There is no attraction between the gas particles.
⋅⋅The volume available to the gas particles is equal to the volume of
the container.
⋅⋅The measured pressure is from collisions of the gas particles with
the walls of the container.
⋅⋅The average kinetic energy is proportional to the temperature of
the system.
Which of the following gas samples have the greatest average molecular speed at
25°C? - ANSWER- Speed of individual gas molecules is inversely proportional to
the molar mass. CH₄ has a molar mass of just over 16 g/mol and is the smallest of
the gases listed. Therefore it has the fastest molecular speed.
What is the difference between effusion and diffusion? - ANSWER- Effusion is
through a pinhole, and diffusion is through open space.
