thermodynamics Flashcards

1
Q

closed vs. open system

A

closed system: exchange energy with outer environment

open system: exchange energy and matter with outer environment

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2
Q

1st law of thermodynamics

A

energy remains constant, only changes form (kinetic energy vs potential energy)

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3
Q

kinetic energy vs potential energy

A

kinetic: heat, pressure, motion
potential: bonds, gradients

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4
Q

enthalpy

A

energy content of bonds
-measure with change in heat in system from reactants –> products

change in enthalpy = change in heat = sum of heat of products - heat of reactants

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5
Q

enthalpy:
exothermic
endothermic
isothermic

A

exothermic: release heat (- change in heat) (usually spontaneous)
endothermic: absorb heat (+ change in heat) (non spontaneous)
isothermic: doesn’t release or absorb heat (zero change in heat)

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6
Q

2nd law of thermodynamics

A

more from order to disorder- entropy in universe always increases

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7
Q

entropy

A

how spread out (dispersed) energy is in a system
-increase entropy (s)= more dispersed
-i.e. a hot pan (concentrated energy) cools down (disperse energy into environment)

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8
Q

Gibbs free energy

A

energy difference between reactants and products

G = H - TS

H=enthlpy
T= temperature
S= entropy

-G= spontaneous, exergonic
+G= non spontaneous, endergonic
G=0 then at equilibrium

-depends on pH, temperature and concentration of reactants and products

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9
Q

standard Gibbs free energy

vs

non standard conditions

A

standard: 298k, pH=7, 1M of products and reactants

nonstandard: G= G* + RT ln [P]/[R]

  • increase [R] = more exergonic (-G)
    -increase [P] = more endergonic (+G)

-even if endergonic and large +G, if have lots more reactant then product then will be exergonic

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10
Q

spontaneous reaction (Gibbs, enthalpy and entropy)

A

-release heat (-H)
-increase entropy (+S)
- (-G)

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11
Q

enzymes

A

catalyst, dont change Gibbs free energy, decrease the activation energy (the energy to break bonds)

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