[Part 2]-P6-particle model of matter 🧈🪶

Question 1

What is specific heat capacity ?

Answer 1

• the specific heat capacity of a substance is, the amount of energy required to raise the temperature of 1kg of the substance by 1*c.

Question 2

In a cooling and heating graph, what happens when the temperature is increased and what happens, when the substance changes state ?

Answer 2

• when the temperature of the substance increases, the kinetic energy of the particles increases
• ; when a substance changes state, the potential energy of a particle increases

Question 3

What can you tell me about heating graphs ? 📈

Answer 3

1) the temperature of the solid is rising, as we are increasing the energy of the particles.

2) when the line becomes horizontal, the temperature stops rising. and at this point, the solid is changing state and melting into a liquid.

3) and during the change of state, we are increasing the internal energy store of the system ;we’re not changing the temperature.

Question 4

What can you tell me about heating graphs, when we reach the melting point ? 📈

Answer 4

• at the melting point, eventually all of the solid will have melted into a liquid, and the temperature will start to rise again.
• this is because, we’re increasing the energy of the particles.

Question 5

What can you tell me about heating graphs, when the lines becomes horizontal again? 📈

Answer 5

6) But when the line becomes horizontal again, the substance is boiling. and the energy we’re putting in, is weakening or breaking the forces of attraction between the particles.

7) once all of the liquid is boiled, the temperature starts to rise again.

Question 6

What can you tell me about the energy we put in, when the substances changes from a solid to a liquid.

Hint: refer to heating graphs ? 📈

Answer 6

• the energy we are putting in, is weakening or breaking the forces of attraction between the particles.
• Therefore allowing the substance to change from a solid to a liquid.
• there are also flat parts on the heating graph, where energy is being transferred by heating, but not being used to change the temperature.

Question 7

Can you tell me about a cooling graph ? 📉

Hint: flat parts

Answer 7

• the flat parts of the graph, show the energy transfer when a substance is condensing or freezing- which releases energy since bonds are forming between particles.

Question 8

What is specific latent heat ?

Answer 8

• the specific latent heat of a substance, is the amount of energy required to change the state of one kilogram of the substance, with no change in temperature.

Question 9

What is the specific latent heat of fusion ?

Hint: change in temperature

Answer 9

• the specific latent heat of fusion, is the energy required to change 1kg of a substance from a solid to a liquid [and vice versa], with no change in temperature.

Question 10

What is the specific latent heat of vaporisation ?

Answer 10

• the specific latent heat of vaporisation, is the energy required to change 1kg of a substance from a liquid to a vapour, with no change in temperature.

Question 11

What is the specific latent heat of fusion 🆚 the specific latent heat of vaporisation ? [2]

Answer 11

• the specific latent heat of fusion, is the energy required to change 1kg of a substance from a solid to a liquid, with no change in temperature.
• ; - the specific latent heat of vaporisation, is the energy required to change 1kg of a substance from a liquid to a vapour, with no change in temperature.

Question 12

What is the difference between specific latent heat 🆚 the specific latent heat of fusion 🆚 specific latent heat of vaporisation ? [4]

Answer 12

• the specific latent heat of a substance, is the amount of energy required to change the state of one kilogram of the substance, with no change in temperature.
• the specific latent heat of fusion, is the energy required to change 1kg of a substance from a solid to a liquid, with no change in temperature.
• ; - the specific latent heat of vaporisation, is the energy required to change 1kg of a substance from a liquid to a vapour, with no change in temperature.

Question 13

What is the pressure of a gas due to ?

Answer 13

• the pressure of a gas, is due to the particles colliding with the walls, of the container that the gas is held in.
• as by colliding with the walls of the container, the gas particles are exerting a pressure.

Question 14

How does frequency and speed, affect gas pressure ?

Answer 14

• the more frequently particles collide with a container, the higher the gas pressure
• and, the higher the speed [or force] of the collisions with a container, the higher the gas pressure

Question 15

How can we increase the pressure of a gas ?

Answer 15

• we can increase the pressure of a gas if:
• we increase the number of collisions per second, by increasing the energy of each collision.
• this can be done by increasing the temperature of a gas.

Question 16

How does decreasing the temperature of a gas, change the pressure of a gas ? [3]

Hint: per second

Answer 16

• the temperature of a gas, is related to the average kinetic energy of the particles.
• at low temperatures, particles have lower kinetic energy, meaning there are fewer collisions per second.
• These collisions are lower energy collisions, meaning at lower temperatures, the gas pressure is relatively low.

Question 17

How does increasing the temperature of a gas, increase the pressure of a gas ? [4]

Answer 17

• the temperature of a gas, is related to the average kinetic energy of the particles.
• at high temperatures, particles have higher kinetic energy, meaning there are more collisions per second. [as the speed of the particles also increases, since kinetic energy is proportional to speed]
• These collisions are higher energy collisions, therefore at high temperatures, the gas pressure is relatively high.