P3: Particle model of matter Flashcards

1
Q

Describe the particle arrangement and motion of particles in a gas (3 main points)

A
  • there are almost no forces of attraction between the particles
  • travel freely in constant random motion
  • high energy
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2
Q

Describe the particle arrangement and motion of particles in a solid (3 main points)

A
  • strong forces of attraction
  • closely fixed regular arrangements
  • low energy thus only vibrate
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3
Q

Describe the particle arrangement and motion of particles in a liquid (3 main points)

A
  • weaker forces of attraction (co. solid)
  • random directions at low speeds
  • more energy (co.solid)
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4
Q

Define density. State the relevant equation and its units

A

The mass per unit volume of a material
density= mass/volume
density: kg/m^3
mass: kg
volume: m^3

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5
Q

State the different states of matter in order of density of atoms

A

solid: most dense
liquid: denser than gas, less dense than solid
gas: least dense

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6
Q

Describe the practical to measure density of a solid object ( a regular object )

A

1) Determine the mass of the object using a balance
2) To work out the volume , measure the sides of the regular object and use the formula : width x height x length
3) Measure the density using using the relevant equation: Density= mass/volume

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7
Q

Describe the practical to measure density for irregular sized objects

A

1) Determine the mass of the object using a balance
2) To find the volume, fill a Eureka can with water
3) Submerge the object into the water. The water displaced by the object will be transferred to the measuring cylinder
4) Record the volume of water in the measuring cylinder. This is the volume of the object
5) Use the mass and volume values to find out the density using the formula

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8
Q

Describe the practical used to find the density of a liquid

A

1) Place a measuring cylinder on a balance and measure its mass.
2) Pour 10 cm3 of liquid into the measuring cylinder and measure its new mass.
3) Repeat these measurements until the measuring cylinder is full
4) For each measurement, use the formula to find the density
5) Take an average of your calculated densities for an accurate density value

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9
Q

What is always conserved when a substance undergoes a change of state?

A

Mass is conserved during a change of state.

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10
Q

How does a change of state differ from a chemical change?

A

the material retains its original properties when reversed

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11
Q

Define Evaporation

A

when a liquid changes into a gas state ( on the surface)

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12
Q

Define Sublimation

A

The direct changing of a substance from a solid state to a gas state, without passing through the liquid phase.

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13
Q

Define condensation

A

The changing from a gas state to a liquid state, when a
substance is cooled.

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14
Q

When water boils in an open pan, why does the mass of the pan of water appear to decrease?

A
  • some of the water will evaporate and turn into water vapour
  • this will leave the pan meaning the mass of the pan will decrease
  • the mass of the system remains constant
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15
Q

Explain the processes involved when a bathroom mirror mists up

A
  • hot water evaporates to form water vapour
  • this water vapour lands on the cooler mirror
  • the vapour condenses and returns to liquid state in the mirror’s surface
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16
Q

what is the internal energy of a substance?

A
  • the energy stored by the particles
  • the sum of the total kinetic and potential energies that make up a system
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17
Q

How does heating affect the energy of a substance?

A
  • heating the system transfers energy to the particles
  • they gain energy in their kinetic stores increasing the internal energy
18
Q

What two things can heating a substance do?

A
  1. increase its temperature
  2. change the state of the substance
19
Q

What three factors determine the size of the temperature change of a system?

A
  1. mass of substance being heated
  2. Type of material (specific heat capacity)
  3. energy inputted into the system
20
Q

Define specific heat capacity

A

The amount of energy
required to raise the temperature of one kilogram of the substance
by one degree Celsius.

21
Q

State the equation used to calculate the change in thermal energy when a substance is heated. Give appropriate units.

A

change in thermal energy (J) = mass (kg)× specific heat capacity (j/kg/*C) × temperature change
∆𝐸𝐸 = 𝑚c∆T

22
Q

DURING A CHANGE OF STATE, describe how the internal energy and temperature of a substance changes (melting to boiling)

A
  • the internal energy increases and is used to break intermolecular bonds / forces of attraction between particles
  • the temperature remains constant until the change of state ends
23
Q

DURING A CHANGE OF STATE, describe how the internal energy and temperature of a substance changes (condensing to freezing)

A
  • internal energy decreases as bonds are forming between particles
  • the temperature remains constant until the change of state ends
24
Q

Define Specific Latent Heat

A

The amount of energy required to change the state of one kilogram of the substance with no change in temperature.

25
Q

State the equation for the energy required to change state. Give appropriate units

A

energy for a change of state (J) = mass (kg) × specific latent heat (j/kg)
𝐸 = 𝑚L

26
Q

Define the specific latent heat of fusion

A

The amount of energy
required to change the state of one kilogram of a substance from solid to liquid state with
no change in temperature.

27
Q

Define the specific latent heat of vaporisation

A

The amount of energy
required to change the state of one kilogram of a substance from a liquid to a gas with
no change in temperature.

28
Q

Describe the motion of molecules in a gas

A
  • constant random motion
29
Q

What factor affects the average kinetic energy of gas molecules?

A
  • the temperature of the substance
  • e.g., the higher the temperature, the higher the average kinetic energy of the molecules
30
Q

What effect does increasing temperature have on the pressure of a gas when held at constant volume?

A
  • pressure of the gas will increase as temperature increases
31
Q

Why does pressure increase as temperature increase ( at constant volume) link to equation

A
  • kinetic energy of molecules increases
  • collisions between molecules becomes more frequent
  • greater force and therefore pressure as pressure= force/area
32
Q

Explain why gas in a low volume container is at a higher pressure

A
  • The gas in container 2 has a higher pressure as there is a decrease in volume
  • this means there are more frequent collisions between the particles and the walls of the container
  • resulting in an increased force which leads to higher pressure as pressure = force/area
33
Q

Describe the force that the pressure of a gas exerts on the walls of its container

A
  • the net force acts at right angles to the container’s surface
  • the force increases as pressure increases
34
Q

Explain how increasing the volume of a gas results in a decrease of pressure

A
  • molecules become more spread out and s time between collisions increases
  • this reduces rate of collisions
  • force exerted on container decreases
  • lower pressure
35
Q

What is Boyle’s Law?

A

For a fixed mass of gas at a constant temperature:
the product of pressure and volume is constant
pV= constant

36
Q

Describe the relationship between pressure and volume according to Boyle’s Law

A
  • Pressure is inversely proportional to volume:
  • if pressure is doubled volume is halved
37
Q

What is the unit used for pressure:

A

Pascal ( Pa )

38
Q

What does it mean to ‘ do work’

A
  • the transfer of energy by a force
39
Q

What increases when you do work on a gas

A
  • internal energy increases
  • can cause an increase of temperature
40
Q

Why does the temperature of air inside a bike pump increase when it is pumped?

A
  • work is done on a gas when it is compressed
  • doing work on a gas increases its internal energy thus increasing its average kinetic energy
  • temperature also increases due to the more frequent collisions
41
Q

explain in terms of particles how evaporation causes the cooling of water

A
  • the particles with the greatest energy 1
  • have enough energy to escape from (the surface of) the water 1
  • therefore the mean energy of the remaining particles decreases
  • as energy decreased, temperature has decreased