Thermal Physics

Question 1

What is absolute zero in K and degrees?

Answer 1

0 K
-273 degrees

Question 2

What is the specific heat capacity of a substance?

Answer 2

The quantity of thermal energy required to raise the temperature of a unit mass of a substance by a unit temperature rise.

Question 3

What is the specific latent heat of a substance?

Answer 3

The amount of energy needed to completely change the state of 1kg of a substance without a change in temperature.

Question 4

What is thermal equilibrium?

Answer 4

When an object gives off the same heat energy as it takes in from the surroundings.

Question 5

What is the relationship in Boyle’s Law? What is constant?

Answer 5

P proportional to 1/V.
Temperature is constant.

Question 5

What is the relationship in the Pressure Law? What is constant?

Answer 5

P proportional to T.
Volume is constant.

Question 6

What is the relationship in Charles’ Law? What is constant?

Answer 6

V proportional to T.
Pressure is constant.

Question 7

What is the combined gas law if none are constant?

Answer 7

(P1xV1) / T1 = (P2xV2) / T2

Question 8

How do you work out the number of moles from the number of molecules?

Answer 8

Divide by Avogadro’s constant.

Question 9

What does isothermal mean?

Answer 9

Constant temperature.

Question 10

What is the area under a graph of pressure against volume?

Answer 10

Work done.

Question 11

List 5 kinetic theory assumptions.

Answer 11

• Molecules have negligible volume compared to the volume of the container.
• Time taken for collisions is negligible.
• Collisions are all elastic.
• Molecules have random, continuous motion.
• Molecules follow Newton’s laws so move in a straight line between collisions.

Question 12

Describe the heating can demonstration.

Answer 12

• Can is heated so particles have more kinetic energy, less needed to equal the outside pressure.
• Steam comes out the top with excess particles.
• Can dumped in water, inside pressure decreases because steam is trapped and condenses.
• Fewer particles on inside so can contracts and crushes because of the imbalance.

Question 13

What is C(rms)?

Answer 13

Average velocity of kinetic particles.

Question 14

What is the pressure for 1 particle in the kinetic theory?

Answer 14

mv^2 / Vol

Question 15

What is the difference between a graph of the kinetic theory and one of a higher tempature?

Answer 15

The higher temperature peaks later and less prominently.