Module 5 - Thermal Physics (Solid, Liquid and Gas)

Question 1

What are the properties of solids in terms of spacing

Answer 1

• Tightly packed molecules
• Because there are strong electrostatic forces of attraction between molecules
• No spacing between molecules
• Meaning they are incompressible

Question 2

What are the properties of solids in terms of ordering

Answer 2

• Regular lattice structure

Question 3

What are the properties of solids in terms of motion

Answer 3

• They have kinetic energy which allows for vibrations about fixed positions

Question 4

What are the properties of liquids in terms of spacing

Answer 4

• Small spacing between molecules
• Meaning they are incompressible
• Tightly packed molecules but less tight than solid
• Because although there is a strong electrostatic attraction it it less than in solids

Question 5

What are the properties of liquids in terms of ordering

Answer 5

• Irregular and random arrangement of particles

Question 6

What are the properties of liquids in terms of motion

Answer 6

• Particles have more kinetic energy than solid particles and so they can slide past each other

Question 7

What are the properties of gases in terms of spacing

Answer 7

• Large spaces between particles meaning they can be compressed

Question 8

What are the properties of gases in terms of ordering

Answer 8

• No ordering of the gasesW

Question 9

What are the properties of liquids in terms of motion

Answer 9

• Particles in gases have the most KE meaning that they moves the most, randomly in all directions

Question 10

Describe Brownian motion in pollen grains

Answer 10

• Pollen grains were dropped on water an instead of staying still they were observed to jitter randomly in all directions.
• This was found to be caused by atoms specifically the one that made up water molecules that exerted forces on the pollen grains to move
• This was the only explanation that aligned with Newtons 1st Law

Question 11

State 2 conclusions about the molecules from the liquid from the motion of pollen grains

Answer 11

• The molecules are smaller than the pollen grains because they could not be seen in the microscope
• The molecules move in random directions

Question 12

What is meant by internal energy

Answer 12

The sum of the randomly distributed kinetic and potential energies within a substance

Question 13

What is Temperature and what is its relation with KE

Answer 13

Temperature is the average KE of particles in a substance. Temperature is directly proportional to KE

Question 14

What is meant by potential energy at this scale

Answer 14

A measure of the electrostatic potential between molecules that increase as the distance between them increases

Question 15

How is Potential energy modelled

Answer 15

It is modelled as negative and as it increases it approaches 0