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55 Cards in this Set
- Front
- Back
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Experiment demonstrate Brownian motion (2) |
put smoke in glass cell and shine beam of light onto it use microscope to view smoke particles |
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How Brownian support random movement of particles |
In Brownian, particles continually change direction so must be acted on by an external force nature of this force is uneven ad random, consistent with force caused by collisions between randomly moving particles |
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mc delta t = mc delta t |
NA |
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Describe and explain factors that influence pressure exerted by gas (5) |
affected by volume of container, increasing volume lowers f of collision between particles and walls so p decrease no of particles - more particles f of collisions increase, increasing total force exerted on container by collisions force prop to mass,heavier particles increase total force exerted on container by collisions, increase pressure speed of particles affect change in momentum when particles collide with container, changing force, changing pressure |
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Why all molecules in flask not same energy (1) |
constantly collide and transferring energy between them, so diff energy |
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Internal energy eqt (1) |
U = 3/2NkT |
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Why pollen particles in water move in zigzag motion (1) |
caused by randomly moving water particles hitting pollen particles unevenly |
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Why average KE of particles in substance constant when substance change phase whilst heated (1) |
energy supplied is alterting bonds , therefore PE of particles instead of increasing their speeds |
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E=VIt=mc delta t |
NA |
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Experiment to measure shc of solid (4) |
Elec heater and thermometer in bock material and cover with insulation turn heater on and heat material so temp increase by about 10K stopwatch to measure how long heater on for use ammeter and voltmeter attached to heater to measure I and V, calc energy supplied E=VIt then E=mc delta t to find c |
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Experiment to find latent heat of fusion for water (5) |
equal masses of ice in 2 identical funnels above beakers heating coil in one funnel and turn on for 3 mins ammeter and voltmeter attached to coil to measure I and V, E=VIt after switch off coil, measure mass of water collected in beakers subtract mass from beaker without coil E=mL |
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Why student should wait after pressure increase before taking readings (1) |
temp has time to stabilise |
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What must be true about gas mass if obey 3 laws (1) |
fixed mass |
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k= R/NA |
NA |
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Eqt that 1/2mc2 = 3/2kT can be derived |
pV=NkT and pV=1/3Nmc2 |
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For ideal gas, what assume about PE |
0J as no forces between particles |
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Assumptions of kinetic model of ideal gases (5) |
gas consist of large no particles move with rapid, random motion collisions with wall elastic negligible volume of molecules compared with volume of container force between molecules negligible except during collisions collision time negligible compared to time between collision |
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Use kinetic theory to explain how gas exert pressure (4) |
Momentum and v of the molecule changes when it collides with the wall Force on the molecule is rate of change of momentum Force on wall is equal to and opposite to the force on the molecule pressure = sum of forces (due to all molecules)/area of wall |
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Smoke particles in air, state conclusions (3) |
air molecules are moving in different directions randomlywith different speedsmass size of air molecules is smaller than smoke particles |
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Thermal equi (1) |
no net heat flow between objects |
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Smoke particles suspended in air, describe their behaviour (1) |
move in random manner |
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How random motion lead to conclusion about nature and properties of molecules of gas (4) |
movement of smoke particles caused by (being hit by) randomly movingair molecules smoke particles are continuously moving because the air molecules arecontinuously moving smoke particles are visible but air molecules are not hence air moleculesmust be (very) small. small movement of smoke particles is due to the large numbers of airmolecules hitting from all sides |
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State Boyle's law (2) |
pressure is inversely proportional to volume for a fixed mass of gas at constant temperature |
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Why energy required to warm water greater than estimate (3) |
Heat used to heat kettle lost to surroudings boil water before kettle switch off |
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Why force on molecule same as to molecule (1) |
Newton 3rd law |
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Why pressure exerted by air on 6 faces of box same (1) |
large number of particles that are moving randomly means that atany instant the number of collisions on each face will be the same |
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Internal energy (1) |
sum of randomly (distributed) kinetic energy and potential energy (due to intermolecular attraction) of molecules |
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Why actual increase in temp lower (2) |
Heat lost to structure of greenhouse Heat lost through glass |
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Why pressure increase when temp increase (1) |
Each collision has greater change of momentum |
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Why release He from balloon as rise (1) |
burst |
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Why He atoms escape from atmosphere when v is less than escape v (2) |
atoms range of speeds some have greater v than escape |
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shc (1) |
Energy required to raise the temperature of a unit mass of a substance by1K |
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Diff between latent heat of fusion and vap (1) |
fusion is energy needed to change a substance from solid to liquid vap liquid togas |
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shc of solid vs liquid (2) |
solid less than l gradient in solid greater and grad inversely prop to shc |
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Heating element of shower, measure rate of flow of water and temp, suggest and explain uncertainty (4) |
rate of flow of water changes as water pressure changes inlet temp changes as ambient temp changes |
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Movement of gas molecules in Brownian (1) |
move in random motion |
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Quick movement of piston cause increase in temp, why (2) |
molecule collides, rebound with higher speed KE prop to temp |
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Show how Boyle's law follow from pV=nRT (2) |
n and temp constant for fixed mass, pV=constant |
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Describe motion of atoms in solid at temp below mp (1) |
vibrate |
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Describe effect of small increase in temp on motion of atoms (1) |
greater f of vibration |
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Describe effect on internal energy and temp of solid when melt (2) |
increase constant |
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shc when no insulating material (2) |
more heat lost to surrounding final temp lower, c higher |
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Why time required and mass of heating greater than calculated (2) |
heat lost through wall hot air escape from room |
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Describe experiment to determine shc of oil (6) Uncertainties and how reduced |
oil in container, heater fully immersed in oil, thermometer ammeter, volt, power supply measure mass, temp, current pd E=Pt=VIt temp varies in oil, stir before readings temp continue to rise after heater off, find max temp |
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Pollen grains in liquid, conclusion (1) |
random motion l molecules smaller than pollen |
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How graph lead to absolute zero (1) |
volume zero at absolute zero |
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Why internal energy of gas differ from liquid phase (2) |
PE of gas more than liquid KE diff |
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Why pressure decrease at low temp (1) |
KE decrease |
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Energy changes when pellets fall (2) |
GPE to KE to thermal on impact |
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Temp rise if mass doubled? (2) |
no Q also double |
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How internal energy of ideal gas related to its temp (3) |
An ideal gas has zero PE
All internal energyis (translational) KE KE prop to kelvin temperature |
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Work done on gas eqt (1) |
W=pV pressure x change in volume |
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Increase in IE of gas = |
heat supplied to system - work done on system |
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Why PE l lower than vapour (1) |
molecules spaced closer to one another so PE less |
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2 assumptions when calc shc |
No heat absorbed by tube all lead falls through same height of tube |
