Heat experiments Flashcards
(41 cards)
calibration curve of a thermometer - method
- 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
calibration curve of a thermometer - graph
x-axis: temperature (°C)
y-axis: length of alcohol column (mm)
Specific heat capacity of water - method
- 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
Specific heat capacity of water - calculating shc
Heat of water + Heat of cal = Heat Energy,
can use to derive:
C𝓌ₐₜₑᵣ = Q-(mcΔΘ)𝒸ₐₗ/mΔΘ𝓌ₐₜₑᵣ
Specific heat capacity of water - unit of shc
J/kg/K
J kg⁻¹ K⁻¹
Specific heat capacity of water - how copper was heated (2007 qs)
-heated using a hot plate (heat energy, conduction)
Specific heat capacity of water -how temp was measured
-thermometer
Specific heat capacity of water - calculate energy lost by hot copper
E = mcΔΘ
Specific heat capacity of water - note when doing calculation
-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!
Specific heat capacity of water - precautions to minimise heat loss
- 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
Specific heat capacity of water - why adding larger mass of copper would improve accuracy (2007 qs)
smaller % error / greater change in water temp
Specific heat capacity of water - improving accuracy
- use very sensitive thermometer
- stir water constantly
- adding a larger mass of copper reduces percentage error + allows greater change in temp
specific latent heat of fusion of ice - method
- 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
specific latent heat of fusion of ice - calculation
(mcΔΘ)𝒸ₐₗ + mcΔΘ𝓌ₐₜₑᵣ = mlᵢ𝒸ₑ + mcΔΘᵢ𝒸ₑ₋𝓌ₐₜₑᵣ
specific latent heat of fusion of ice - how mass of ice was measured
mass of calorimeter + water + melted ice - mass of calorimeter + water
specific latent heat of fusion of ice - how it was ensured temp of ice was at 0
- crushed
- melting
specific latent heat of fusion of ice - ways to insulate calorimeter
- insulator wrapped around calorimeter (styrofoam)
- lid
-placed inside plastic container
specific latent heat of fusion of ice - characteristics of thermometer suitable for use in this experiment
- small heat capacity
- graduate to 0.1°C
- suitable range
- reacts quickly
specific latent heat of fusion of ice - why use warm water
- 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
specific latent heat of fusion of ice - why use dried, melting ice
- 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
specific latent heat of fusion of ice - what should be the approx room temp to minimise experimental error?
-midway between initial and final temp (of water in calorimeter)
specific latent heat of fusion of ice - calc energy lost by cal and warm water
energy lost = (mcΔΘ)𝒸ₐₗ + mcΔΘ𝓌ₐₜₑᵣ
specific latent heat of fusion of ice - why crush the ice
-crush to make sure temp is constant
specific latent heat of fusion of ice - reduce heat loss
- use lid
- transfer ice using plastic spatula
- avoid splashing
- insulate calorimeter (styrofoam)
