4.4 Matter Very Simple

Question 1

Which temperature scale starts at absolute zero?

Answer 1

The Kelvin scale.

Question 2

What happens at absolute zero?

Answer 2

All particles have minimum possible kinetic energy.

Question 3

What is 0K in degrees Celsius?

Answer 3

-273.15ºC

Question 4

Which temperature scale is used in thermal physics equations?

Answer 4

The Kelvin scale.

Question 5

What is Boyle’s law?

Answer 5

At a constant temperature, the pressure and volume of a has are inversely proportional. pV = constant.

Question 6

What is Charle’s law?

Answer 6

At a constant pressure, the volume of a gas is directly proportional to its absolute temperate. V/T = constant.

Question 7

What is the Pressure law?

Answer 7

At a constant volume, the pressure of a gas is directly proportional to its absolute temperature. p/T = constant.

Question 8

What equation do you get from combining the three gas laws?

Answer 8

pV/t = constant

Question 9

What is the value of the molar has constant?

Answer 9

8.31 J mol^-1 K^-1

Question 10

What is the ideal gas equation?

Answer 10

pV = nRT

Question 11

What does n represent in the ideal gas equation?

Answer 11

The number of moles of gas present.

Question 12

What is Avogadro’s constant, NA?

Answer 12

The mole of gas particles in one mole.

Question 13

What is the value of Avogadro’s constant?

Answer 13

6.02 x 10^23

Question 14

What is the Boltzmann’s constant equivalent to?

Answer 14

R / NA

Question 15

What is the meaning of the Boltzmann’s constant?

Answer 15

The gas constant for one particle of gas.

Question 16

What is the value of Boltzmann’s constant?

Answer 16

1.38 x 10^-23

Question 17

What is the equation of state of an ideal gas?

Answer 17

pV = NkT

Question 18

Using a cubic box analogy, explain why particle velocity is proportional to pressure.

Answer 18

The faster a particle is travelling, the more momentum is exchanged with the walls more frequently. This means a larger force on the wall and therefore a higher pressure.

Question 19

Using a cubic box analogy, explain why the number of particles is proportional to pressure.

Answer 19

Each particle exerts a force on the wall as it hits it so total force is proportional to number of particles. This results in a higher pressure since P = F / A.

Question 20

Using a cubic box analogy, explain why the volume of the box is proportional to the pressure.

Answer 20

Describing the size of the box increases the rate of collisions and reduces the area of the walls. Hence a higher pressure.

Question 21

Why is mean square speed used?

Answer 21

To take into account the difference in particle velocities.

Question 22

Why is the mean square speed multiplied by one third?

Answer 22

Because there are 3 dimensions, it can be assumed that a third of all particles are moving in one dimension at a time.

Question 23

Give the third equation involving pV.

Answer 23

pV = 1/3 Nm(ć^2)

Question 24

What is r.m.s. speed?

Answer 24

Root mean square speed, the typical speed of a particle.

Question 25

Give four assumptions used in kinetic theory.

Answer 25

The gas contains a large number of particles. The particles move rapidly and randomly. The motion of the particles follows Newton's Laws. Collisions between particles themselves and the container are perfectly elastic.

Question 26

What is a random walk of a particle?

Answer 26

A model of the movement of particles.

Question 27

What does a random walk involve?

Answer 27

Moving a step in a random direction repeatedly.

Question 28

What is the relationship between average distance moved after N steps and number of steps moved?

Answer 28

Distance is proportional to √N.

Question 29

What is the zeroth law of thermodynamics?

Answer 29

If body A and body B are both in thermal equilibrium with body C, body A and body B must be in thermal equilibrium with each other.

Question 30

Where does thermal energy flow to and from?

Answer 30

Regions of high temperature to low temperature.

Question 31

What is the definition of specific thermal capacity, c?

Answer 31

The amount of energy needed to raise the temperature of 1kg of a substance by 1K.

Question 32

Give the word equation for specific heat capacity.

Answer 32

energy change = mass x specific thermal capacity x change in temperature

Question 33

Give the symbol equation for specific heat capacity.

Answer 33

∆E = m c ∆θ

Question 34

What are the units of c, specific heat capacity?

Answer 34

J kg^-1 K^-1

Question 35

Describe the shape of the graph comparing proportion of particles with a given speed and particle speed.

Answer 35

A Maxwell-Boltzmann distribution curve.

Question 36

What happens to particle speeds as the temperature of a gas increases?

Answer 36

The average particle speed increase and the maximum particle speed increases. The means the speed distribution curve will be more spread out.

Question 37

What happens when gas particles collide?

Answer 37

Energy is transferred between the particles.

Question 38

When gas particles collide, some may particles may gain speed whilst others...

Answer 38

Slow down.

Question 39

Describe the speed of gas particles between collisions.

Answer 39

Constant.

Question 40

Give three assumptions used in kinetic theory.

Answer 40

There are no attractive forces between particles. Any forces that act during collisions are instantaneous. Particles have a negligible volume compared with the volume of the container.

Question 41

Despite the change in energy of individual particles as a result of collisions, the total energy of the system...

Answer 41

Is unchanged.

Question 42

The total energy of the system is constant so the average speed of the particles in the system will stay the same provided...

Answer 42

Temperature of the gas is constant.

Question 43

What the internal energy of a gas?

Answer 43

The sum of kinetic and potential energy of the particles within a system.

Question 44

What is average kinetic every of an individual particle proportional to?

Answer 44

Absolute temperature.

Question 45

Give the equation for average kinetic energy of an individual particle, 1/2 m ć^2

Answer 45

1/2 m ć^2 = 3/2 (n R T)/N

Question 46

Give the two equations used to derive the equation for average kinetic energy of an individual particle.

Answer 46

pV = 1/3 Nm(ć^2) and pV = nRT