CHEM 219 Exam # 3 Questions and Answers Grade A+
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.
Under what conditions are gases most likely to behave ideally? - Answer-Gases are
more likely to behave as ideal gases at low pressures and high temperatures.
Particles are moving faster and are farther apart, therefore they are less likely to
interact with each other
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.
Under what conditions are gases most likely to behave ideally? - Answer-Gases are
more likely to behave as ideal gases at low pressures and high temperatures.
Particles are moving faster and are farther apart, therefore they are less likely to
interact with each other
