722123
Description
Flashcards by Moa Lindström, updated more than 1 year ago
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Created by Moa Lindström
over 11 years ago
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| Question | Answer |
| Element | material made up of just one type of atom |
| Molecule | contains more than one type of atom |
| Compounds | materials made from molecules |
| Gas | no fixed shape or volume. (ideally) no force between molecules |
| Liquid | no fixed shape but fixed volume. force between molecules not so strong so molecules can move around |
| Solid | fixed shape and volume. molecules held in position by a force, vibrate but don't move around |
| Temperature (T) | a measure of how hot or cold an object is. it is temperature that determines the direction of heat flow |
| Celsius --> Kelvin | add 273 |
| Kelvin --> Celsius | subtract 273 |
| Thermal capacity (C) | the amount of heat needed to raise its (somethings) temperature by 1*C. (J*C^-1) C=Q/(change in)T, where Q is quantity of heat |
| Specific heat capacity (c) | the amount of heat required to raise the temperature of 1kg of the material by 1*C. (unit: J kg^-1 *C^-1). c=Q/m(change in)T |
| Boiling | takes place throughout the liquid and always at the same temperature |
| Evaporation | takes place only at the surface of the liquid and can happen at all temperatures |
| Specific latent heat (L) | amount of heat required to change the state of 1kg of the material without change of temperature. L=Q/m (unit: J kg^-1) (latent = hidden) |
| Energy supplied | power x time |
| The ideal gas | made up of a large number of perfectly ELASTIC, (IDENTICAL) TINY SPHERES moving in random motion. there are no forces between molecules (except when they collide);they move with constant velocity between collisions |
| Pressure | force/area |
| Equation of state for an ideal gas | PV=nRT. P(ressure), V(olume), n(umber of moles), R (molar gas constant(booklet)), T(emperature) |
| Isobaric | constant pressure |
| Isochoric | constant volume |
| Isothermal | constant temperature |
| Internal energy | the sum of all the KE of all the molecules |
| Work done | work is done when the point of application of a force moves in the direction of the force. force exerted on piston = PxA. work done when piston is moved (change in) d(istance), work done=PxAx(change in)d -> Ax(change in)d=change in volume V -> work done = Px(change in)V |
| Sign of work | + when a gas does work it is pushing the piston out = positive. - if work is done on the gas then something must be pushing the piston in = negative |
| First law of thermodynamics | simple version; if a gas expands and gets hot, heat must have been added. according to the law of conservation of energy; Q=(change in)U+W. (Q- amount of heat (change in)U - internal energy, W - work done by gas) |
| Using P(ressure)V(olume) diagrams | ~change in VOLUME tells us whether work is done by the gas or on it. ~change in TEMPERATURE tells us whether the internal energy goes up or down. ~change in pressure is not interesting... |
| Adiabatic contraction | an adiabatic transformation is one where no heat is exchanged (Q=0). steeper than a "normal" temperature curve. first law of thermodynamics; Q=(change in)U+W -> 0=(change in)U+W -> (change in)U=W |
| Net work done (thermodynamic cycles) | the net work done during a (thermodynamic) cycle is the difference between the work done BY the gas and the work done ON the gas. this is equal to the area enclosed by the cycle on a PV diagram |
| Thermodynamic cycle | isochoric and isobaric changes. (volume and pressure) |
| The Carnot cycle | isothermal and adiabatic changes. (temperature) |
| The second law of thermodynamics | it is not possible to convert heat completely into work. (since energy always spreads out) |
| Entropy | about the spreading out of energy. ~entropy is a measure of how spread out or disordered the energy has become. ~saying entropy has increased implies that the energy has become more spread out. (change of)S=Q/T, unit: J K^-1. S=entropy, Q=quantity of heat, T=temperature |
| Second law of thermodynamics in terms of ENTROPY | in any thermodynamic process, the total entropy ALWAYS increases |
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