What happens when the temperature of a solid is increased?
Particles gain Ke and eventually gain enough energy to break bonds, causing the average space between particles to increase. The particles can move freely and the solid has melted.
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What happens when the temperature of a liquid is increased?
Particles gain more Ke and move faster and further apart. Particles gain enough energy to break free from their neighbors and the liquid has boiled to become a gas.
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What does Brownian motion show, and what can be concluded from this?
Smoke particles are seen as points of light and their jiggling is due to collisions with much smaller invisible air particles. This provides evidence for the rapid and random motion of molecuels.
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Define latent heat of fusion.
The amount of energy needed to change a solid into a liquid with no rise in temp.
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Define latent heat of vaporisation.
The amount of energy needed to change a liquid into gas with no rise in temperature.
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When heating a body, to change the phase of the body, what 3 things are needed?
Input of energy, No change in temp, an increase in molecular potential energy.
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When heating a body, between changes of phase, what 3 thigns are needed?
An input of energy, a rise in temperature, an Increase in molecular kietic energy.
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During heat transfer, where does thermal energy transfer to and from.
From a region of higher temperature to a region of lower temperature. eg. from a warm room to a cooler room.
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Define the term thermal equilibrium.
Occurs when there is no net transfer of thermal energy between two regions and they reach the same temperature.
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Define Specific heat capacity and state what it is measured in.
c = E/mc (delta pheta) Where c is shc, E is energy in joules, m is mass in kg and delta pheta is the change in temperature in K or C. SHC is measured in J Kg^-1 or (degrees)C^-1, or J Kg^-1 K^-1
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Define internal energy.
The internal energy of a gas is the sum of the RANDOMLY DIST. Kinetic and potenital energies of all the molecules in the gas.
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What are the 7 stages involved in causing the pressure of a gas?
1. Molecules collide elastically with walls. 2. They rebound. 3.Therefore there is a change in momentum. 4. Divided by time between collisions give the rate of change of momentum 5. Equal and oppo force on the wall. 6. add forces.7. P=totalforce/area
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What are the two ways in which the internal energy of a gas could be increased?
1. do work on the gas by compressing it to reduce the volume. 2. heat teh gas causing molecules to collide with the walls more vigorously causing an increase in Ke.
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Define absolute zero.
0K, the temperature at which all substances have minimal internal energy.
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How to convert degrees Celsius to Kelvin.
+273.15
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What are the four properties of gas that we can measure?
Pressure, Volume, Temperature and mass
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Define Boyle's Law.
V ∝ 1/P for fixed T (in K) and m.
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Define Charle's Law
V ∝ T for fixed p and m.
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Define The pressure law.
P ∝ T for fixed V and m.
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In what conditions do gases not obey the 3 laws and why?
In extreme values of low temp or high pressure. This happens b/c inter-molecular forces are no longer negligible.
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What are the ideal gas laws?
pV = NkT or pV=nRT N=number of atoms. n = number of moles.
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How is the number of moles found?
n = Mass of gas/Molar mass.
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How is the number of molecules found?
N= n (Na) (Na = avo constant.)
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How is the mean Ke of a molecule in an ideal gas found?
E = 3/2 kT
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What are the 4 assumptions made for ideal gases?
1.Molecuels make elastic collisions. 2.Time taken for collisions to occur is negligible when compared to the time duration between collisions. 3.Molecules have negligible volume. 4. There are no inter-molecular forces.
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What are the implications of the 4 assumptions of an ideal gas in terms of internal energy?
All the internal energy of an ideal gas is Ke, there is no molecular PE.
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Other cards in this set
Card 2
Front
What happens when the temperature of a liquid is increased?
Back
Particles gain more Ke and move faster and further apart. Particles gain enough energy to break free from their neighbors and the liquid has boiled to become a gas.
Card 3
Front
What does Brownian motion show, and what can be concluded from this?
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