15) ideal gases

Question 1

What is Avagadro’s constant?

Answer 1

A number of particles equal to the number of atoms in 12 grams of carbon-12

Question 2

What is one mole of a substance?

Answer 2

An amount in which the number of atoms/molecules is equal to Avogadro’s constant.

Question 3

How do you find the mass of one atom from its nucleon number?

Answer 3

Multiply nucleon number by the atomic mass unit (u) in kg.

Question 4

How is the atomic mass unit defined?

Answer 4

It is 1/12th the mass of a Carbon-12 atom

Question 5

How do you calculate the number of particles from the number of moles of a substance?

Answer 5

Number of particles = number of moles × Avagadro’s constant

Question 6

How do you find the molar mass of a substance from the molecular mass?

Answer 6

Molar mass = Molecular mass x Avagadro’s Number

Question 7

How do you find the total mass of a substance from the number of moles?

Answer 7

number of moles x molar mass

Question 8

How do you calculate the number of moles of a substance from the number of particles?

Answer 8

Number of particles÷Avagadro’s number

Question 9

How do you find the molar mass of an element from its nucleon number?

Answer 9

Molar mass is equal to nucleon number in grams.

Question 10

Boyle’s law: Pressure is inversely proportional to…

Answer 10

Volume for a fixed mass of gas at constant temperature

Question 11

Charles’ law: Volume is proportional to…

Answer 11

Absolute temperature for a fixed mass of gas at constant pressure.

Question 12

Gay Lassac’s Law: Pressure is proportional to…

Answer 12

Absolute temperature for a fixed mass of gas at constant volume

Question 13

Avogadro’s law: Volume occupied by a gas is proportional to…

Answer 13

Number of particles/moles if pressure and temperature are constant.

Question 14

How do you find absolute zero from a pressure temperature graph?

Answer 14

Extrapolate the line to find the x-intercept.

Question 15

What is R in pV = nRT?

Answer 15

Molar Gas Constant (8.31)

Question 16

What is N in pV = NkT?

Answer 16

Number of particles

Question 17

What is n in pV = nRT?

Answer 17

Number of moles

Question 18

What is k in pV = NkT?

Answer 18

Boltzmann constant

Question 19

What units of temperature should be used in the ideal gas equation?

Answer 19

Kelvin

Question 20

What is the equation of state for an ideal gas?

Answer 20

pV = NkT OR pV = nRT

Question 21

What is an ideal gas?

Answer 21

A theoretical gas that obeys the gas laws at all pressures and temperatures

Question 22

What are the SI units of pressure?

Answer 22

Pascal (Pa or Nm⁻²)

Question 23

What is the definition of pressure?

Answer 23

The force per unit area exerted normally to a surface

Question 24

What is the relationship between root mean square speed of particles in a gas and absolute temperature?

Answer 24

rms speed is proportional √(absolute temperature)

Question 25

Why does increasing the temperature of an ideal gas increase pressure?

Answer 25

Particles have greater kinetic energy so there is a greater rate of collisions and greater change in momentum per collision.

Question 26

Why does increasing the volume of an ideal gas decreases pressure?

Answer 26

P=F/A. Force exerted decreases as the rate of collisions with the container decreases and the surface area increases.

Question 27

According to Newton's second law if a particle experiences a change in momentum...

Answer 27

There must be a force acting on the particle.

Question 28

According to Newton's third law if a container exerts a force on a particle...

Answer 28

The particle must exert a force on the container.

Question 29

How do you calculate the mean square speed of gas particles from their velocity?

Answer 29

Square the magnitude of the velocity of each individual gas molecule and then take the average of these values.

Question 30

How do you calculate root mean square speed of a gas?

Answer 30

Square the magnitude of the velocity of each individual gas molecule, take the average of these values and then take the square root.

Question 31

Why is root mean square speed used instead of velocity?

Answer 31

Average velocity is zero.

Question 32

What is N in pV = ¹/₃ N m (c)²

Answer 32

Number of particles

Question 33

What is (c)² in pV = ¹/₃ N m (c)²

Answer 33

Mean square speed

Question 34

What is ³/₂kT equal to?

Answer 34

The mean kinetic energy of a gas particle

Question 35

What form is the internal energy of an ideal gas?

Answer 35

Purely kinetic (i.e. no potential energy)

Question 36

Why is there no potential energy in an ideal gas?

Answer 36

Because there are no force between particles (except during collisions).

Question 37

What is ³/₂NkT equal to?

Answer 37

Total internal energy of an ideal gas.

Question 38

Kinetic theory assumption concerning volume

Answer 38

The volume of the particles in a gas is negligible compared to the volume of the container

Question 39

Kinetic theory assumption concerning forces

Answer 39

There are no electrostatic forces between particles except during collisions

Question 40

Kinetic theory assumption concerning motion

Answer 40

Particles are in continuous, rapid, random motion.

Question 41

Kinetic theory assumption concerning collisions

Answer 41

The collisions particles undergo with each other and the container are all elastic

Question 42

Kinetic theory assumption concerning time

Answer 42

The duration of collisions is negligible compared to the time between collisions

Question 43

What is the relationship between absolute temperature and the average KE of particles in a substance?

Answer 43

Absolute temperature is proportional to average kinetic energy of the particles in a substance.