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# Chapter 3

### Thernodynamics

Energy capacity to do work
What is a state function? property whose value does not depend on the path taken to reach that specific value
State Function Example Mountain trail vs. train
Not sure if it's a state function? Do I care how I got the final value ; if no then it's a state function
State Change the change in value between the final and starting position
The sentence to remember the 10 state functions Many people deserve entertaining tele-vision, everyone enjoys great comedies
Enthalpy energy transfer in physical and chemical processes
Enthalpy Change the measure of energy during a chemical reaction
What kind of energy is present in chemical bonds of molecules potential energy
What is temperature a measure of random motion of particles
What is Heat? transfer of energy between 2 objects due to temperature difference
Enthalpy Change amount of heat given off or absorbed
What can be said if the PE of products is lower than the reactants energy given off, exothermic
If PE of products is higher than reactants then reaction is endothermic energy is needed
Calculate Enthalpy delta H (sum of enthalpies of products)-(sum of enthalpies of reactants) if neg then exothermic, if pos. endothermic
What is a thermal chemical equation special type of chemical equation that shows enthalpy change going from reactants to products
1 calorie = ? Joules 4.184 J=1 calorie
SI Unit for Heat Joule
Calorie Amt of energy (heat) needed to raise temperature of 1 gram of water 1 deg. C
Calorimeter a device used to experimentally determine heat associated with a chemical reaction
Calorimetry The science of measuring heat transfer when a substance absorbs or releases energy
Amt of heat energy needed to change temperature of a substance depends on three things amt of substance, amt of temp change, ID of substance (chemical composition)
Specific Heat Capacity amount of energy required to change temp of 1 gram of a substance by 1 deg C
Units for Specific Heat Joule/g-deg C
Equation to calculate heat or energy of a reaction (Q) Q=SmdeltaT S= specific heat (J/g degC), m mass in grams Delta T temp in C
2 types of calorimeters bomb-food burned-heat transfered to water surrounding the burn chamber Q=SmdeltaT 2. coffee cup-chem rxn takes place in insulated styrofoam cup, heat transfered to outside cup same formula
What happens the the energy you gat from the food you eat if it isn't all used up? turns to fat
Entrophy (S) measurement of the randomness or disorder in a system
Spontaneous Reaction process that occurs by itself w/out any outside work
Silly Little Goats Entropy increases with the order of phases: solid (lowest)-liquid-gas (highest)
What does heating do to the entropy of the substance increases it
How do moles of a gas affect entropy (S) more moles yields higher entropy
How do you calculate entropy change deltaS delta S= S(final)-S(initial)
Spontaneity of a process is affected by... temperature
Gibbs Free Energy G amount of total energy change that is available or free to do useful work G=H-TS
What kind of reaction if delta G is negative spontaneous reaction, we can get energy out
What kind of reaction if delta G is positive Non spontaneous reaction
What can we say about a boulder as it related to the calculate delta G neg=boulder going down hill positive, no way the boulder goes up the hill
Gibbs (Free) Energy as it relates to what we eat amt. of energy left over after chem rxn has taken place; excess energy stored as fat
Spontaneity direction a reaction will take w/out outside interference
Enthalpy (H) how much energy released or absorbed during a chemical reaction
Green Eagles Hit Moaning TV's Suddenly delta G= delta H- (T)(deltaS) neg H heat released, exo; pos H heat absorbed, endo
? A Battery electrochemical cell- converts chemical energy to electrical energy
Galvanic Cell a spontaneous chemical reaction produces electrical energy
What is another name for a galvanic cell? voltaic cell
What kind of reaction is taking place in a galvanic cell? ReDox reaction oxidation electrons lost, anode; reduction electrons gained, cathode
what is the cell potential energy, E measure of the spontaneity of the reaction; different 1/2 cells produce different voltages
The larger the cell potential the more _____ we get out of the cell work
Relationship of Potential Energy (E) and Gibbs Energy (G) used to measure spontaneity of a reaction delta G = -nFE : G standard free energy for the reaction at standard conditions; E standard voltage or cell potential energy for the rxn n=#moles electrons transferred F=96,500J/molV
delta G & E have opposite signs spontaneous reaction neg G and + cell potential energy
Temperature amount of kinetic energy in a substance
Heat amount of energy in a substane
Specific Heat Energy = Heat Energy / (m)(delta T) Specific Heat of water = 1 calorie
Why don't large bodies of water not have large temperature changes? water can absorb a lot of heat w/out much temperature change (high specific heat)
2nd Law of Thermodynamics aka... Law of Entropy: total energy=useable (free energy) + unusable energy
2nd Law of Thermodynamics not all energy can be used as kenetic energy decreases heat lost due to friction is increasing
1st Law of Thermodynamics aka Law of the Conservation of Energy Energy can not be created or destroyed
What does the direction an electric field depend on? direction always points in the direction a positive particale would move within the field pos-repel;neg-attract
Created by: roisinmac19