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Chem 105 "Midterm 4"
| Term | Definition |
|---|---|
| energy | capacity to do work and/or transfer heat |
| law of conservation of energy-mass | mass/energy cannot be created nor destroyed, only transferred or converted |
| 1st law of thermodynamics | Euniv = 0 (constant) |
| 3 forms of energy radiant kinetic potential | radiant - light kinetic - energy of motion potential - stored in object due to position or composition |
| chemical potential energy | energy due to positions in atoms (bonds, electrostatic interactions) |
| kinetic energy - 3 types | translational, rotational, vibrational |
| temp is proportional to average ____ energy | kinetic |
| internal energy | KE + PE of a system |
| system | part of universe being studied or isolated |
| systems: isolated closed open | isolated - no energy or matter transferred (thermos) closed - only energy transferred (sealed Tupperware) open - both energy and matter transferred (soup bowl) |
| change in energy is | final energy - initial energy |
| state function | quantity that depends on final-intial, not the path it took to get there path independent |
| change in energy is | q+w |
| q (heat) | spontaneous flow of KE from warm object to a cooler one |
| work (w) | exertion of a force through distance |
| endothermic | heat in to system q>0 work done on system w>0 |
| exothermic | heat out of system q<0 work done by system on surroundings w<0 |
| endothermic vs exothermic | thermal energy entering system thermal energy exiting system |
| heat always flows from ___ object to a ____ one! | heat always flows from warmer object to a cooler one! |
| endothermic phase changes | melting, vaporization, sublimation |
| exothermic phase changes | freezing, condensation, deposition |
| work = | -P(Vfinal-Vinital) |
| if change in volume is (+)... | EXPANSION makes work (-) system does work on surroundings |
| if change in volume is (-) | COMPRESSION makes work (+) work done on system by surroundings |
| heat capacity | how much energy needed to raise the T of an object by 1 C q=C deltaT |
| specific heat capacity | energy needed to raise T of 1 g of an object by 1 C (at constant P) q=mCdeltaT |
| molar heat capacity | amount of energy needed to raise T of 1 mol of a substance by 1 C (at constant P) q=nCdeltaT |
| metals =_____ heat capacity water/ammonia = ____ heat capacity | metals =low heat capacity (low energy to heat) water/ammonia = high heat capacity (lots of energy to heat) |
| caloriometry | measuring calories, experimentally determining quantity of heat/energy transferred during a physical of chemical process |
| -qsubstance = | qwater |
| -(mCdeltaT) substance = | (mCdeltaT)water |
| bomb calorimetry | measuring energy content in food |
| -qrnx = | qwater |
| -qrxn also = | Ccal delta T |
| enthalpy, H | measures total energy of system plus internal energy to push aside surroundings to make space for system |
| H>0 H<0 | endothermic (+) exothermic (-) |
| q=n deltaHvap enthalpy of vaporization | vaporizing a liquid at boiling point |
| q = -n deltaHvap | condensing a gas into liquid |
| q = n deltaHfus enthalpy of fusion | melting a solid at melting point |
| q = -n deltaHfus | freezing a liquid at freezing point |
| heating curve | solid --> solid/liquid --> liquid --> liquid/gas --> gas |
| deltaHrxn enthalpy of reaction | energy released for the reaction as written |
| if coefficients of the rxn are multiplied then... and if reaction is reversed... | enthalpy of rxn is multiplied by that integer as well enthalpy of rxn sign is flipped |
| Hess's law | a process that is a sum of two rxns, the enthalpy of rxn is also equal to the sums of there enthalpies |
| deltaHf standard enthalpy of formation | 1 mol of substance is formed formed by pure elements elements in standard states |
| standard states - gases | noble gases, H2, N2, O2, F2, Cl2 |
| standard state - liquids | Br2, Hg |
| standard state - solids | everything else C= solid = graphite |
| deltaHf for pure elements in their standard states is | 0 |
| deltaHbreaking bonds bond enthalpy | energy required to break 1 mol of a certain bond in gas phase |
| bond enthalpies are always ____ because it always _____ energy to break a bond | bond enthalpies are always positive because it always requires energy to break a bond |
| energy is _____ and _____ when bonds form | negative and released |
| fuel value | energy/g |
| fuel density | energy/mL |
| environmental value | how much energy a fuel produces per unit of greenhouse gas emissions (CO2) |
| entropy | dispersion of energy at a certain T |
| spontaneous process | once started, a process that continues to occur without outside intervention |
| greater dispersion of energy = | spontaneous |
| disperse positions of particles disperse KE | positional (configurational) entropy excite different vibrational, rotational, and translations of different bubbles |
| 2nd law of thermodynamics | in any spontaneous process, the entropy of the universe increases deltaSuniv > 0 |
| change in entropy of the universe is = | entropy of system + entropy of surroundings |
| microstates (W) | a unique arrangement of the positions and momenta of particles in a system |
| "accessible" microstates | microstates possible at certain time T |
| more microstates = _____ entropy = ____ favorable = ____ likely | more |
| thermal equilibrium is the most ______ arrangement | most which is why heat always flows from warmer to cooler object |
| boltzman equation | entropy increases when W increases |
| S=0 for a perfect | crystal lattice |
| we can measure both __ and ________ for entropy | S and change in S |
| standard molar entropy - S knot | the absolute entropy of 1 mol of a substance in its standard state at 298 K and 1 bar |
| factors that affect S | mass increases, entropy increases molecular structure/size increases, entropy increases rigidity increases, entropy decreases |
| factors affecting deltaS | phase change direction, positive entropy volume increases, positive entropy temp increases, kinetic energy increases, positive entropy |
| deltaSuniv > 0 deltaSuniv < 0 deltaSuniv = 0 | spontaneous non-spontaneous constant |
| lst law 2nd law 3rd law | Euniv=0 deltaS>0 (for spontaneous rxn) S of perfect crystal = 0 |
| delta S is proportional to | q/T must be isothermal (have constant T) to be true |
| isothermal | constant T |
| exothermic processes ______ the entropy of surroundings | raise |
| more heat = _____ change in S colder starting temp = _____ change in S | greater |
| deltaSsurr = | -deltaHsys/T |
| Gibb's free energy equation deltaH deltaS(-T) deltaG | deltaH - total energy of system (enthalpy) delta S (-T) energy made available due to entropy deltaG - free energy |
| free energy | energy available to do useful work |
| G<0 | exergonic, spontaneous |
| G>0 | endergonic, non-spontaneous |
| endergonic vs endothermic exergonic vs exothermic | gonic - change in free energy (Giibb's) thermic - change in heat (enthalpy) |
| H -, S + | G is always <0 always spontaneous |
| H -, S - | G<0 at lower temp spontaneous at lower temp |
| H +, S + | G<0 at higher temp spontaneous at higher temp |
| H +, S - | G is always >0 always non-spontaneous |
| isothermal | constant temperature |
| isothermal + reversible processes | ice to water bending and unbending paper clip |
| irreversible processes | egg fried paper burned popcorn popped |
| q/T = Ssys | phase changes |
| q/T = Ssurr | when surroundings are so large, T won't really effect it |
| G is also a ____ function | state |
| coupled reactions | couple a spontaneous reaction with a nonspontaneous reaction to get the energy you need |
| example of coupled reactions | muscle movement ATP to ADP + P |
| G and H both = 0 when | 1 mol of element is in standard state |
| glycolysis | conversion of 1 mol glucose to pyruvates with 2 mole of ATP (takes energy) |
| ATP hydrolysis | breakign down ATP to ADP + P |
| the released energy of ATP hydrolysis drives the glycolysis energy up | yay |
| thermodynamically favorable means | delta G < 0 spontaneous downhill |
Created by:
anyasalmon