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Science - continued > Particle model > Flashcards

Particle model Flashcards

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1
Q

What does the kinetic theory state?

A

Everything is made of many small particles which are constantly moving

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2
Q

Describe the arrangement for solids

A

Forces of attraction hold the particles very closely together - they vibrate but do not move around which explains why solids can keep their shape but not be compressed

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3
Q

Describe the arrangement for liquids

A
  • Particles are moving faster and so forces of attraction between the particles are not strong enough to keep the fixed position
  • the particles can move past each other so liquids flow and take shape of their container
  • the particles are still close together so cannot be compressed
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4
Q

Describe the arrangment for gases

A
  • particles are far apart and moving around quickly

- gases are compressible and expand to fill their container

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5
Q

Explain how a state change is a physical change

A

The particles end up in a different arrangement, but the number of particles does not change (mass conservation) - no new substances are made, and the substance can recover its original properties

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6
Q

What is the density of a substance

A

The mass of a certain volume of the substance

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7
Q

When is a substance the most and least dense?

A

Most - solid

Least - gas

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8
Q

How do you investigate the densities of solids and liquids

A
  1. put an empty beaker on a balance and set it to 0
  2. use a measuring cylinder to measure 50cm3 of a liquid and pour it into a beaker and write down the reading on the balance which is the mass of 50cm3
  3. find the mass of the solid and write it down
  4. stand a displacement can on the bench with its spout over a bowl and fill it with water until the water just starts to come out the spout
  5. hold a cylinder under the spout and carefully drop the solid into the can and if it floats, push it down (your finger shouldn’t be in the water though)
  6. stand the cylinder on the bench and read the volume of the water collected which is the same as the volume of your solid
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9
Q

What is the formula for density?

A

density = mass / volume

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10
Q

What is thermal energy

A

Energy transferred to a system by heating that is stored in the movement of particles

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11
Q

What happens to the vibrations of the particles when the thermal energy increases?

A

The vibrations increase

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12
Q

What is the temperature a measure of?

A

A measure of the movement of the particles

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13
Q

How do you maintain a store of thermal energy

A

The amount of energy transferred to the surroundings by heating needs to be reduced by surrounding the warm object by insulating materials such as wool, foam or bubble wrap

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14
Q

What does the amount of thermal energy stored in an object depend on?

A
  • its temperature
  • its mass
  • material its made of
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15
Q

What is the specific heat capacity of an material

A

The amount of energy it takes to increase the temperature of 1kg of the substance by 1 degree

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16
Q

When does the temperature change during a state change?

A

The temperature increases as more energy is being supplied to the solid, but while it’s melting, the temperature stays constant because the energy is being used to break the arrangement

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17
Q

What is the specific latent heat

A

the amount of energy it takes to make 1kg of a substance, change state

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18
Q

Which needs more energy, evaporation or melting?

A

Evaporation

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19
Q

How do you melt ice before finding the specific heat capacity

A
  • Put a boiling tube full of crushed ice into a heatproof beaker and note the temperature
  • Put the beaker on a tripod and gauze and pour hot water from a kettle and keep it warm using a bunsen burner
  • Measure the temperature every minute and stop after three minutes when all the ice is melted
  • make sure you have noted the time when the ice appeared to start melting and when it has now fully melted
20
Q

How do you take the measurements for calculating the specific heat capacity

A
  • put a polystyrene cup in a beaker on a battery scale balance note it down and then change it to 0
  • add water to the cup and measure the mass
  • put a thermometer in the cup and use a 12V electric heater making sure its fully submerged under the water and connect it to a joulemeter
  • record the water temperature, turn on the heater and then gently stir the water using a thermometer
  • after 5 minutes, check the temperature and record it also checking the joulemeter
21
Q

What is the temperature of a gas a measure of?

A

The average kinetic energy of the particles in the gas - the faster the average speed, the higher the temperature (heating the gas increases the kinetic energy and so the temperature increases)

22
Q

What is the pressure of gas based on?

A

Due to forces on the walls of a container caused by the moving particles hitting the walls - the faster the particles are moving, the more frequent the collisions will be and so exert more force when they collide

23
Q

What does increasing the temperature of a gas do?

A

Increases the speed of the particles and so increases the pressure

24
Q

What is the unit for pressure

A

Pascals (1Pa = 1 N/m^2)

25
Q

What is absolute zero

A

The lowest temperature that is theoretically possible at which the motion of particles which constitutes heat would be minimal

26
Q

What is the temperature for absolute zero

A

-273.15 degrees C

27
Q

What does the Kelvin temperature scale measure

A

measures temperatures relative to absolute zero (units are kelvin) - absolute zero is 0K on the scale

28
Q

How do you convert Kelvin to Celcius and vice versa

A

Kelvin to Celcius = subtract 273

Celcius to Kelvin = add 273

29
Q

What is gas pressure?

A

The force exerted by gas particles colliding with the wall of their container. Gas pressure is the force exerted by a gas on a specific area.

30
Q

How does gas pressure increase?

A

When the gas particles in a larger volume are forced into a smaller volume and so hit the walls more often and so the force on the walls increases

31
Q

How does work done tie into gas pressure?

A

For example, when using a bicycle pump, each time you push the pump handle, the force is transferring energy to the gas inside the pump (work done)

32
Q

What does elastic and inelastic meaning

A

Elastic - the object will return to its original shape when forces are removed
Inelastic- they will keep their new shape after the forces are removed

33
Q

Give an example of an object which behaves elastically with small forces but with larger forces behaves inelastically

A

Metal springs (behave elastically) but if they are stretched too big they become permanently damaged

34
Q

What is the extension of a spring (or another object)?

A

The change in length when forces are applied

35
Q

What is the relationship between the extension and force

A

They are directly proportioanl - if the extension doubles, the force doubles

36
Q

When does the relationship between the extension and force become non-linear?

A

When the spring is stretched too far

37
Q

What is the spring constant?

A

The force needed to produce an extension of 1 metre

38
Q

What is pressure a measure of?

A

The force on a unit of surface area where the force is normal (at right angles) to the surface

39
Q

What is the pressure at sea level?

A

100 000 Pa

40
Q

What does the pressure of a fluid depend on?

A

The depth of the fluid - the deeper you are the more weight of the fluid there is above you to exert pressure (e.g when you are at the bottom of the ocean, the pressure is high and when you are at the top of a mountain the air pressure decreases as there is less air above you)

41
Q

What is atmospheric pressure due to?

A

The whole depth of the atmosphere above you

42
Q

If you dive 10 underwater, how much pressure will you feel compared to at the surface

A

Double the pressure than at the surface

43
Q

How many more times is water denser than the air at sea level

A

800

44
Q

What is upthrust in a fluid due to?

A

Due to the difference in pressure above and below the object

45
Q

What must happen to the upthrust in order for an object to float

A

The upthrust must be equal to the weight of the block

46
Q

What happens to objects which are not equal in upthrust and weight in the block

A

They sink

Science - continued (9 decks)

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