6.2 Thermal Physics Flashcards

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1
Q

What is internal energy?

A

The sum of the potential and kinetic energies of a system.

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2
Q

How can you increase the thermal energy of a system?

A

We can increase it by heating it up or doing work on the object.

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3
Q

Explain the energy changes that occur during a change of state.

A

During change of state the potential energy of the particles change but the kinetic energies doesn’t change.

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4
Q

What equation can be used to determine the energy required to change the temperature of a substance?

A

Q = mcΔT

Q - J
m - kg
c - JK-1
T - K

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5
Q

What equation can be used to determine the energy required to change the state of a substance?

A

Q = ml

Q - J
m - kg
l - Jkg-1

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6
Q

What is the Ideal gas equation?

A

pV = nRT

p - Pa
R - is the Molar Gas constant, 8.31 Jmol-1K-1
n - is the number of mols
T - K
V m^3
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7
Q

What is the first law of thermodynamics?

A

ΔU = Q - W

Where Q = the heat added to a system
And W is the work done by the system

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8
Q

What is the specific heat capacity of a substance?

A

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

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9
Q

What is the specific latent heat of a substance?

A

The energy required to change the state per unit mass (1kg) of a substance, while keeping the temperature constant.

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10
Q

What is an ideal gas?

A

A gas that:
● The gas molecules don’t interact with each other.
● The molecules are thought to be perfectly spheres.

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11
Q

What is the internal energy of an ideal gas equal to?

A

New answer

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12
Q

What is Boyle’s law?

A

Pressure is inversely proportional to volume, providing temperature is constant.

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13
Q

In an ideal gas, how would increasing the volume change the temperature of the gas, while the pressure remains constant?

A

As you increase the volume, you also increase the temperature.

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14
Q

Explain how increasing the temperature of a balloon, while keeping the volume the same will increase the pressure.

A

● As the temperature increases, the average kinetic energy increases.
● Therefore the particles are travelling at a higher speed on average
● There are also more frequent collisions
● Which means the particles would exert a greater force
● Which would cause a increased rate of change of momentum
● Therefore increasing pressure.

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15
Q

What is absolute zero?

A

At - 273℃

This is where objects have no/minimum kinetic energy.

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16
Q

What is Avogadro’s constant? (in words)

A

The number of atoms there are in one mole of a substance.

17
Q

True or false: ‘All collisions between particles and between particles and the wall are elastic’ is an assumption of an ideal gas?

A

True

18
Q

State an assumption of an ideal gas related to time?

A

The time for each collisions is negligible in comparison to the time take between collisions.

19
Q

Describe 6 assumptions of the ideal gas equation.

A

● The particles move randomly
● They follow Newton’s laws of motion
● No intermolecular forces act between particles
● Volume of the particles is negligible compared to the volume of the container they are in
● The time for each collisions is negligible in comparison to the time taken between collisions.
● All collisions between particles and between particles and the wall are elastic

20
Q

What is meant by the root mean square speed?

A

The square root of the mean of the squares of the speeds of the molecules.

21
Q

What is Brownian motion?

A

Brownian motion is the idea that very small objects have random motion in a liquid or gas due to random bombardment by the molecules in this substance. This movement will be fractionally more on one side than the other so a force will push it for an instant as the net forces shifts directions. This random motion is Brownian Motion and gives evidence for the existence of atoms.