THERMODYNAMICS
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Closed system | exchange of heat and work but not matter with the surroundings
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isolated system | no exchange of heat, work, or matter with the surroundings
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open system | exchange of heat, work, and matter with the surroundings
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What are the characteristics of a state function? | path-independent
--> only depend on final and initial states
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What do state functions include? | enthalpy, entropy, free energy change (delta G), and internal energy change (delta U)
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Endothermic / exothermic reaction, delta H = | positive / negative
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What does delta H mean? | change of heat content of a reaction
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What is standard state? | natural, lowest energy state
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What is standard state for oxygen? | O2
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Why is bond dissociation energy positive? | energy input is required to break bonds
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Why is enthalpy of formation negative? | energy is released when bonds are formed
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Calculate bond dissociation energy. | bond dissociation energy of all bonds in reactants - bond dissociation energy of all bonds in products
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Calculate enthalpy of formation. | enthalpy of all bonds in products - enthalpy of formation of all bonds in reactants
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T / F. A change in one degree C is the same as a change in 1 K | TRUE
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heat capactiy | the amt of heat required to raise the temp of something by one degree celsius
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molar heat capacity | heat capacity per mole ( Joules / mol*C)
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specific heat capacity | heat capacity per mass (Joules / g*C)
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How many Joules of energy does it take to raise the temp. of 1 gram of water by 1 degree celsius? | 4.2 J
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How many joules of energy does one calorie equal? One Calorie? | 4.2 J
4200 J
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How many calories does one Calorie equal? | 1000
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What is free energy? | energy available that can be converted to do work
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Are all exothermic rxns spontaneous? | NO --> depends on entropy
delta G = delta H - T*delta S
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Do spontaneous rxns happen quickly? | not necessarily
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Zeroth Thermodynamic law | heat flows from hot objects to cold objects to achieve thermal equilibrium
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If Ta = Tb, Tb = Tc, then? | Ta = Tc
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First Thermodynamic Law | Conservation of energy
--> change in total energy of a system is equal to contributions from heat and work
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What does delta E equal to in thermodynamics? | q + w
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When is q positive? negative? | -heat absorbed into system
-heat leaks out of system
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When is work positive? negative? | -work done on system
-work done by system
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T / F. ALL energy is equivalent even if they are in different forms. | TRUE
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Second thermodynamic law | universe is increasing in entropy
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Why is entropy increasing? | irreversibility nature of real processes
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Room temperature in celsius? body temperature? | 25 / 37
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How to convert from celsius to fahrenheit? | C * 1.8 + 32 = F
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Conduction | heat transfer by direct contact
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Convection | heat transfer by flowing current through a fluid medium
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Radiation | heat transfer by EM radiation through emission of photon energy (infrared range)
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Can radiation occur in a vacuum? | YES
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heat of fusion | energy input needed to melt something from solid to liquid at constant temperature
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heat of vaporization | energy input needed to vaporize something from liquid to gas at constant temperature
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adiabatic process | no heat exchange --> deltaE = W
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isothermal process | no change in temperature
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isobaric pressure | pressure is constant, W = P*deltaV
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isochoric process | volume is constant, W = 0
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When does the q = mcdeltaT formula work? | if no phase change is involved
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Heat of fusion / vaporization is measured in | Joules
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Heat of fusion equation | q = delta H (fusion) * number moles
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Heat of vaporization equation | q = delta H (vaporization) * number moles
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At what temperature does ice melt? Water freeze | 0 degrees C
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At what temperature does water boil? Steam condense? | 100 degrees C
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A refrigerator takes in _____ and releases _____. An engine takes in ______ and releases ____. | work / heat
heat / work
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Why does air blown from pursed lips feel cool on the skin? | Expansion of a gas is an endothermic process as it hits the skin
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Formula for Work with gas expansion / compression | W = - P * deltaV
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Forming bonds is an _____ process Breaking bonds is an ______ process. | exothermic / endothermic
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Expansion of a gas is _________. Compression of a gas is ________. | endothermic / exothermic
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Third Law of Thermodynamics | entropy of a perfect crystal at 0 K is O
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Relate E, q, and w. | delta E = q + w
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Favorable at? -S positive, H negative -S negative, H positive -S positive, H positive -S negative, H negative | -all temperatures
-at no temperatures
-at high temperatures
-at low temperatures
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Rank the enthalpy changes for: melting, evaporation, sublimation | sublimation > evaporation > melting
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Why does a higher reaction temperature accelerate the rxn? | greater KE within the reactants
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After reaction completes, what then proceeds? | equilibrium
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S deals with ____ while G deals with _____. | -entropy
-whether or not rxn is spontaneous
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Does Keq give any information about kinetics? | NO --> only thermodynamics
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Does the slow or fast step have the highest energy to get over? | slow
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What defines the rate of a reaction? | activation energy and kinetic region
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What type of diagram is activation energy read from? | free energy
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What does deltaGo show? | free energy change when a reaction goes from standard conditions to equilibrium
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Does enthalpy say anything about favorability of a reaction? | NO
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In an exothermic reaction, are the products lower or higher than reactants? | lower
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In an endothermic reaction, are the products lower or higher than the reactants? | higher
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Do cyclic compounds have more or less entropy than linear compounds? | less --> more rigid and cannot rotate
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For G and H of formation, an element in its basic form has a value of? | 0
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What are the diatomic gases? | Fluorine, Oxygen, Nitrogen, Chlorine, Hydrogen
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What are the diatomic liquids? | Bromine
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What are the diatomic solids? | Iodine
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How many moles of products do formation reactions create? | one mole
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In an exo rxn, are the bonds formed stronger or weaker than those broken? | stronger
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What are weaker bonds? On the energy diagram are they high or low? | long bonds / high
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Does a tertiary carbon form a stronger or weaker bond with hydrogen than a primary carbon? | weaker --> carbocation stability
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What is the heat capacity fo rwater | 1 cal / g*K
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How to find the final temp. created from mixing 2 solutions with different temperatures? | mcdeltaT = - mcdeltaT
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Do solids have higher or lower heat capacities than liquids? | lower --> only vibrational kinetic energy
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materials with high heat capacities experience smaller or greater temperature increases? | smaller
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Is the enthalpy of vaporization greater or less than the heat of fusion? | greater
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strong base + strong acid = | water and neutral salt
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Why must a lid be used in a calorimetry experiment? | To prevent heat loss from convection and evaporation **
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Is warm air less dense or more dense than cool air? | less dense
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What happens to an object as it radiates photon energy? | object becomes cooler and molecules move less energetically
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What are 2 formulas for work? | W = F*delta d
W = -P * delta V
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What does it mean when "q" is positive vs. negative? | -positive = heat flows from surroundings into system
-negative = heat flows from system into surroundings
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Thermodynamic Energy Equation | delta E = q + w
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When does work = 0? | constant volume
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If a precipitation reaction is favorable, then delta G =? | negative
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Does water or salt water have the greater heat capacity? | salt water
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The lower the heat capacity, the greater or less the temperature increase? | greater
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When something has greater heat capacity, it also has greater? | kinetic energy
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