Yr 13 - Thermal Physics (2 of 2)

Question 1

Equation for finding the number of moles
(Not given in EQ book)

Answer 1

N = n x Na

N = Number of particles
n = Number of moles
Na = Avogadros constant

Question 2

What is molar mass?

Answer 2

Mass in grams of one mole of substance

Question 3

5 Assumptions for the kinetic theory of gas

Answer 3

-> Large No. molecules in random, rapid motion.
-> Particles occupy negligible volume compared to the volume of gas.
-> All collisions are perfectly elastic
-> Time of collisions is negligible compared to time in-between collisions
-> Negligible forces between particles except during collisions

Question 4

What is a mole

Answer 4

Unit of measurement for amount of substance

Question 5

Quantify 1 mole

Answer 5

One mole contains exactly (NA - avogadros) elementary entities (atom, molecule, ion etc)

Question 6

What do the gas laws describe?

Answer 6

The relationship between temperature, pressure and volume.

Question 7

What is Boyles law?

What must you do to prove this accurately?

Answer 7

For a fixed amount of gas a constant temperature its pressure is inversely proportional the its volume.

• Slowly increase the pressure so that the temp remains constant

Question 8

What does Avogadro’s constant represent?

Answer 8

The number of particles in one mole.

Question 9

How to you calculate the root mean squared speed?

Answer 9

• Square the numbers
• Calculate the mean
• Square root the answer

Question 10

What do these words mean?

• Macroscopic
• Microscopic

Answer 10

• Visible to the naked eye
• Invisible the the naked eye (visible under a microscope)

Question 11

Describe the Maxwell-Boltzmann distribution and what is it?

Answer 11

Probability - Velocity graph

• n shape
• Most probable speed at peak
• Average speed to right of peak
• Root mean squared speed to right of average speed

Gives probability that the velocity of a particle in an ideal gas is within a given range.