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41 Cards in this Set
- Front
- Back
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constant value that the mass action expression gives you
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equilibrium constant- Keq
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what is the only thing that can change the value of Keq
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temp
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rate
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product/time
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catalyst
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lowers the Ea-outs the particles together so you need less energy
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exothermic
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A+B-->C+energy
feels warm |
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endothermic
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A+B+energy-->C
feels cold |
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factors affecting rate of reaction
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1. temp (for every 10 degree incrase,it doubles the rate of reaction
2. concentration-adding particles increases it 3. particle size -larger surface area=faster 4. catalyst- helps orient the molecules 5. inhibitor- slows down rate |
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effective collisions
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collisions must be effective in order for there to be a reaction
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what 2 things make collisions effective
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1. adequate rate
2. correct angle |
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kinetics
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the branch of chemistry considered with the rates and mechanics of reaction
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princeton clock
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-shows intermediate stage
-goes from clear--> yellow (intermediate)--> to black |
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rate determining step
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the one that happens the slowest (only as fast as the slowest part)
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Rochelle salt and hydrogen peroxide (H2O2)
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shows how a catalyst works
-oxygen is reactive and kills germs when H202 is broken down -it is breaking down when u see bubbles -colbalt chloride (CoCl2) acts as a catalyst for reaction -increases the rate of reaction but it is not effected -add peroxide to Rochelle salt- breaks down peroxide end= colbat chloride, water, some things in ROchelle salt |
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enthalpy
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the change in the amount of heat during a reaction
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is heat of reaction negative or positive in exothermic
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negative
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what happens to energy as bonds are formed?
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energy is released
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what environmental conditions cause peroxide to decompose
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heat and light
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equilibrium
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is reached when the rate of the forward reaction equals the rate of the reverse reaction
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what will get this reaction to move forward
A+B-->C+D |
removing D
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Keq
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equilibrium constant- how far a reversible reaction goes forward
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mass action expression
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[C] x [D]
--------- [A] x [B] |
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what is the unit of mass action expression (keq)
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mole/L
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what Keq FAVORS the products
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when it is GREATER THAN 1
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what keq favors the reactants
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when it is LESS THAN 1
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saturated solution
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solution at physical equilibrium
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physical equilibrium
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condensation and evaporation occuring at the same time
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what different kinds of stress can you put on equilibrium and what are the affects
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1. change in pressure- if you increase the pressure, it will shift towards the side with less moles
2. change in concentration- increasing causes more effective collisions A+B---> C+D I D I I if you start with decrease, the other two on the other side wiill decreawse, if you start with increase the other two on the other side will increase 4. change in temp- an increase in temperature favors teh ENDOthermic reaction |
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Haber process
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nriogran (nitrates) explosives
N2+ 3H2<--->2NH3 + heat |
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entropy
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S- easure of disorder/measure of randomness
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negative and positive entropy
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increasing- +
decreasing- - |
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ex. of S increasing
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S-->L-->G
increase # of particles increase temp -dissociation/dissolving-more particles NaCl--(H2o)-->Na+ + Cl- -decrease pressure (only in gases) |
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gibbs free energy equation
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deltaG= deltaH - TdeltaS
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G
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free energy- energy available to do work
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when is G spontaneous
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when delta G is negative
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when is G improbable
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when delta G is prositive
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when is G equilibrium
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when delta G is zero
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what are two fators that determine whether a reaction is spontaneous
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the size and irection of heat (enthalpy) change and entropy changes
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NO2<-->N2O4 colors etc.
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NO2<---------->N2O4
dark brown light brown higher temp lower temp mixture- hot=darker cold=lighter shows physical equilibrium -shows frwrad and reverse reaciton bc of color change |
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Le Chateliers principle
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explains how a system at equilibrium responds to relieve any stress on the system
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stress
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any change in temp, concentration, or pressure on an equilibrium system
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when do pressure changes not have an effect on the rate of reaction
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when only solids and liquids are involveed
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