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29 Cards in this Set
- Front
- Back
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thermochemistry
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the study of changes in energy that occur during chemical and physical changes
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Kinetic Energy
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energy of motion
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Potential Energy
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stored energy (waiting to happen)
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Chemical Potential Energy
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stored energy in chemical bonds (making and breaking)
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Heat
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(q) - an energy transfer from one object to another, always going from hot to cold
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Law of Conservation of Energy
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energy cannot be created or destroyed by ordinary chemical or physical means, but it can be transferred
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Exothermic
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energy is being released - energy on product side
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Endothermic
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enery is being absorbed - energy on reactant side
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SI Unit
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Joule (J)
1 cal = 4.184 J |
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Common Unit
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Calorie
1 Cal= 1000 cal= 1kcal a calorie is the specific heat of water |
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Heat Capacity
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the amount of heat required to raise the temperature of a substance by 1 degree C
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Specific Heat
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the amount of heat required to raise the temperature of a substance by 1 degree C per gram (C)
- C of H2O is 4.18 J/degreeC |
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Calorimeter
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-measures calories
-opposite temperature of actual thing qcalorimeter = -qreaction |
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Equation for Calorimetry
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q = mC(deltaT)
q=heat m=mass C=specific heat deltaT=change in temperature |
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Thermochemical Equations
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chemical equations which include energy as a reactant or product
-involve energy stoichiometry |
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Reaction Coordinates
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relative charts that show energy of reactants and products, the added energy needed to start a reaction, and amount of heat produced
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delta H
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the amount of heat produced
products-reactants -deltaH is exothermic,A to B +deltaH is endothermic,B to A q=deltaH=enthalpy |
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State Function
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functions which are independent of the path taken
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Hess' Law Method
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find deltaH using multiple equations and combining them to find the given equation
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Standard Heats of Formation
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(deltaHfdegrees) method
-the change in enthalpy that accompanies the formation of the compound from its elements in their standard state - use chart on pg 530 = sum of deltaH products-sum of deltaH reactants |
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Collision Theory
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-reactions are car accidents
- they need to be near each other and hit for reaction to occur -Factors: Temperature, Pressure, Concentration, Catalysts, Particle Size(Surface Area) |
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Reversible Reaction
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reaction that can go from A to B, or B to A
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Chemical Equilibrium
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the rate of forward and reverse are the same
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Le Chatelier's Principle
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if stress is applied to a system at equilibrium, the system will change in a way to relieve the stress
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Free Energy
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( G )
- energy available to do work or the amount you can use - change is Gibbs |
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Spontanious Reaction
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reaction can occur by simply bringing reactants together, without stirring or anything
- deltaG is negative |
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Entropy
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( s )
- the measure of disroder - high mess=high entropy |
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Law of Disorder
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natural tendency is for a system to maximize disorder, increasing s
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Free Energy equation
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deltaG=deltaH-TdeltaS
deltaG=change in Gibbs(G) deltaH=heat of reaction T= temperature in kelvin deltaS= change in entropy |
