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19 Cards in this Set
- Front
- Back
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The first law of thermodynamics |
ΔU = Q - W |
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Ideal gas equation |
pV = nRT n = number of moles R = universal gas constant (8.31JK^-1mol^-1) T = absolute temperature in kelvin (K) nR is constant for a fixed mass of gas therefor pV/T = constant |
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Boyle's law |
pV = constant for a isothermal change |
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Pressure Law |
P/T = constant for a gas of fixed volume |
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Charles Law |
V/T = constant |
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Internal Energy (U) |
The sum of the total kinetic energy of a systems constituent particles and (if not an ideal gas) the total potential energy of the particles. |
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To increase the internal energy of a gas... |
Heat the gas. Do work on the gas by compressing it. |
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To decrease the internal energy of a gas... |
Cool the gas. Allow the gas to expand against atmospheric pressure or a piston. |
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No-flow process |
A process during which the fluid does not move in or out of the system. |
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Isothermal process |
A process in which the system stays at the same temperature. pV = constant At a constant temperature the average molecular kinetic energy is constant so the internal energy is constant so ΔU =0 and Q = W. Requires the gas to be kept in a thin-walled vessel that is an excellent conductor surrounded by a constant temperature bath. Changes must take place slowly so the temperature is always constant throughout. |
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Isothemals |
The higher the temperature, the larger the value of nRT so the the curve is further away from the origin. |
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Work done (W) = |
pΔV |
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Constant-volume process |
W=0 as ΔV = 0 so ΔU = Q |
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Adiabatic Process |
A process where no energy is transferred in or out of the system by heating from or to the external environment. Q = 0 so ΔU = -W pV^γ = constant TV^(γ-1) A system with perfect insulation would undergo an adiabatic change, or if the change happens so fast that there is not enough time for heat to transfer in or out (like in a heat engine). Can be considered reversible as not heat is lost out of the system. |
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Atomicity (γ) |
A value dependent upon the degrees of freedom of a system (The number of methods by as system can absorb energy) Dependant upon the molecular structure. |
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γ= |
cp/cv |
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cv = |
The energy required to produce a unit temperature rise in a unit mass of the gas at constant volume |
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cp = |
The energy required to produce a unit temperature rise in a unit mass of the gas at constant pressure |
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Cyclic Process |
A process in which the system undergoes two or more consecutive changes such that the final state is the same as the initial state. |
