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LC Physics > Heat experiments > Flashcards

Heat experiments Flashcards

1
Q

calibration curve of a thermometer - method

A
  • place both thermometers into a beaker of melting ice, leave until mercury thermometer reads 0°C
  • mark height of alcohol on other thermometer with marker
  • record temp on mercury thermom.
  • set up as in diagram
  • heat water by 10°C as per mercury thermom. Record this temp + mark new height of alcohol
  • repeat until mercury thermom. reads 100°C
  • take out alcohol thermom.
  • Measure. using metre stick, from kink in inner tube to each point, matching lengths to corresponding temps recorded on mercury thermometer
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2
Q

calibration curve of a thermometer - graph

A

x-axis: temperature (°C)

y-axis: length of alcohol column (mm)

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3
Q

Specific heat capacity of water - method

A
  • find mass of empty copper calorimeter using electronic balance
  • add enough water to submerge heating coil, find mass of c + water
  • subtract mass of cal to find mass of water
  • Set up as per diagram
  • Wait 2 mins, find temp of water in cal. This is initial temp of water + cal
  • switch on joulemeter + power supply
  • stir water throughout
  • allow current to flow until there is a 15°C rise in temp
  • switch off ps + j
  • record reading on joulemeter. Record final temp reading when water temp stopped rising. This is final temp of water + cal
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4
Q

Specific heat capacity of water - calculating shc

A

Heat of water + Heat of cal = Heat Energy,
can use to derive:

C𝓌ₐₜₑᵣ = Q-(mcΔΘ)𝒸ₐₗ/mΔΘ𝓌ₐₜₑᵣ

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5
Q

Specific heat capacity of water - unit of shc

A

J/kg/K

J kg⁻¹ K⁻¹

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6
Q

Specific heat capacity of water - how copper was heated (2007 qs)

A

-heated using a hot plate (heat energy, conduction)

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7
Q

Specific heat capacity of water -how temp was measured

A

-thermometer

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8
Q

Specific heat capacity of water - calculate energy lost by hot copper

A

E = mcΔΘ

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9
Q

Specific heat capacity of water - note when doing calculation

A

-read question carefully, a q in 2007 said that “a hot copper was added to heat up the water”, not a heating coil! In the calculations, it would’ve been:

Heat loss by hot copper = Heat gained by cal + water!

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10
Q

Specific heat capacity of water - precautions to minimise heat loss

A
  • surround calorimeter in insulating material (eg. styrofoam, plastic container)
  • use lid
  • avoid splashing
  • polish calorimeter
  • use low heat capacity thermometer
  • pre-cool water to 7°C below room temp
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11
Q

Specific heat capacity of water - why adding larger mass of copper would improve accuracy (2007 qs)

A

smaller % error / greater change in water temp

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12
Q

Specific heat capacity of water - improving accuracy

A
  • use very sensitive thermometer
  • stir water constantly
  • adding a larger mass of copper reduces percentage error + allows greater change in temp
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13
Q

specific latent heat of fusion of ice - method

A
  • find mass of empty copper cal
  • crush ice w/ pestle + mortar
  • place ice + probe from data logger in beaker. When visibly melting, ready to use
  • Warm water in another beaker to 35°C, pour into cal. Find mass of cal + water
  • Record temp of melting ice + room temp
  • stir water in cal until it is 5°C higher than room temp
  • record temp of water
  • dry ice + add into cal, stir until it melts
  • Record temp once temp is 5°C below room temp. This is the end temp for cal, water, ice
  • find mass of cal, water, ice
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14
Q

specific latent heat of fusion of ice - calculation

A

(mcΔΘ)𝒸ₐₗ + mcΔΘ𝓌ₐₜₑᵣ = mlᵢ𝒸ₑ + mcΔΘᵢ𝒸ₑ₋𝓌ₐₜₑᵣ

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15
Q

specific latent heat of fusion of ice - how mass of ice was measured

A

mass of calorimeter + water + melted ice - mass of calorimeter + water

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16
Q

specific latent heat of fusion of ice - how it was ensured temp of ice was at 0

A
  • crushed

- melting

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17
Q

specific latent heat of fusion of ice - ways to insulate calorimeter

A
  • insulator wrapped around calorimeter (styrofoam)
  • lid

-placed inside plastic container

18
Q

specific latent heat of fusion of ice - characteristics of thermometer suitable for use in this experiment

A
  • small heat capacity
  • graduate to 0.1°C
  • suitable range
  • reacts quickly
19
Q

specific latent heat of fusion of ice - why use warm water

A
  • to speed up melting of the ice
  • in order to melt a larger mass of ice
  • allow for heat loss and heat gain to balance out
20
Q

specific latent heat of fusion of ice - why use dried, melting ice

A
  • dry to make sure you are only adding ice, not water
  • melted ice would have already gained latent heat
  • melting ice is at 0°C
21
Q

specific latent heat of fusion of ice - what should be the approx room temp to minimise experimental error?

A

-midway between initial and final temp (of water in calorimeter)

22
Q

specific latent heat of fusion of ice - calc energy lost by cal and warm water

A

energy lost = (mcΔΘ)𝒸ₐₗ + mcΔΘ𝓌ₐₜₑᵣ

23
Q

specific latent heat of fusion of ice - why crush the ice

A

-crush to make sure temp is constant

24
Q

specific latent heat of fusion of ice - reduce heat loss

A
  • use lid
  • transfer ice using plastic spatula
  • avoid splashing
  • insulate calorimeter (styrofoam)
25
Q

specific latent heat of vaporisation of water - method

A
  • find mass of empty copper cal
  • put cold water into cal, find mass of cal + Water
  • subtract mass of cal to find mass of water
  • record initial temp of cold water
  • set up as per diagram, do not submerge tubing into water yet
  • allow water in round bottom flash to boil
  • dry end of tubing + plunge into cold water in cal
  • leave until 10-15C rise in water
  • remove heat source + tubing from water
  • stir water in cal + record highest final temp it reaches
  • find mass of cal, water + condensed steam. Subtract mass of cal + Water to find mass of steam
26
Q

specific latent heat of vaporisation of water - draw labelled diagram (2015 qs)

A

pay attention to question! it says a polystyrene cup was used, not a calorimeter

27
Q

specific latent heat of vaporisation of water - calculation

A

mlₛₜₑₐₘ + mcΔΘₛₜₑₐₘ-𝓌ₐₜₑᵣ = mcΔΘ𝓌ₐₜₑᵣ + (mcΔΘ)𝒸ₐₗ

28
Q

specific latent heat of vaporisation of water - two assumptions when calculating when using polystyrene cup (2015 qs)

A
  • good/perfect insulator

- low/negligible heat capacity

29
Q

specific latent heat of vaporisation of water - how did the steam being dried improve accuracy?

A
  • calculations assume that only steam is added,

- otherwise steam would have lost its latent heat of vaporisation

30
Q

specific latent heat of vaporisation of water - how did the water initially in the cup being cooled increase accuracy?

A

heat gained = heat lost

31
Q

specific latent heat of vaporisation of water - how water cooled below room temp

A

-water taken from fridge

32
Q

specific latent heat of vaporisation of water - how steam was dried

A

use of steam trap

33
Q

specific latent heat of vaporisation of water - how to determine mass of steam

A

final mass of calorimeter plus contents - initial mass of calorimeter and water

34
Q

specific latent heat of vaporisation of water - why use a sensitive thermometer

A
  • for greater accuracy
  • reduce percentage error
  • more significant figures
35
Q

specific latent heat of vaporisation of water - why dry steam used

A
  • condensed steam would have already lost its latent heat

- calculations assume only steam added

36
Q

specific latent heat of vaporisation of water - how steam dried

A

-use steam trap + insulated delivery tube

37
Q

specific latent heat of vaporisation of water - why use a thermometer with low heat capacity

A
  • absorbs less heat from system
  • calculations assume no energy is transferred to thermometer
  • so it does not skew the results
38
Q

specific latent heat of vaporisation of water - why pre-cool water

A

allow for heat loss and heat gain to balance out

39
Q

specific latent heat of vaporisation of water - room temp was 19, student start exp with water at 13, why? (mock qs)

A

-so heat lost to surroundings while water is above room temp = heat gained from surroundings when water below room temp

40
Q

specific latent heat of vaporisation of water - how steam trap dries the steam

A

it ensures only steam enters the cal as the insulation stops the steam from condensing into water

41
Q

if initial temp of steam not given

A

assume its initial temp is 100

LC Physics (25 decks)

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