Ch14&15: Thermal Physics

Question 1

Use the kinetic model to describe the structure of a solid.

Answer 1

• The atoms or molecules are regularly arranged and packed close together.
• They are held together by strong electrostatic forces.
• But they can vibrate, and do have kinetic energy.

Question 2

Use the kinetic model to describe the structure of a liquid.

Answer 2

• Atoms and molecules are closer together, but are free to move around.
• Weaker electrostatic forces than a solid
• They have more kinetic energy than a solid,

Question 3

Use the kinetic model to describe the structure of a gas.

Answer 3

• Negligible electrostatic forces of attraction
• more kinetic energy than a liquid
• random and far apart
• move randomly in random directions at different speeds

Question 4

What is brownian motion?

Answer 4

particles moving in random movements in random directions

Question 5

How does the amount of electrostatic potential energy compare between the three states of matter?

Answer 5

Gas: 0 potential energy
Liquid: negative electrostatic potential energy value
Solid: largest negative electrostatic potential energy value

Question 6

What is internal energy?

Answer 6

The sum of the randomly distributed kinetic and potential energies of all molecules/atoms within a system.

Question 7

Describe the internal energy of a substance at absolute 0.

Answer 7

Kinetic energy will be zero, and potential energy will be very small.

Question 8

Define specific heat capacity of a substance.

Answer 8

The amount of energy required per unit mass to change the temperature by 1K

Question 9

Define the terms of this equation.

N = n x Na

Answer 9

N= total number of atoms/molecules
n= number of moles
Na= Avogadros constant

Question 10

What are the 4 assumptions of the kinetic theory of gases?

Answer 10

1. Atoms occupy a negligible volume compared with gas volume.
2. Collisions with one another and the container walls are perfectly elastic.
3. Collision time is negligible compared with non-collision time.
4. Except during collisions, electrostatic forces between atoms are negligible.

Question 11

If mass is constant,

pv/t = ?

Answer 11

A constant

Question 12

What is Boyle’s law?

Answer 12

the pressure exerted by a fixed amount of gas is inversely proportional to its volume at a constant temperature.

Question 13

How can the Boltzmann constant be calculated?

Answer 13

k = R/Na