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Chem 122
chapter 16
11
Chemistry
Undergraduate 3
08/21/2009

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Term
Chemical Equilibrium
Definition
when the rate of the forward reaction equals the rate of the reverse reaction.
Ex. aA + bB = cC + dD
Term
When products are formed, they react to produce reactants.
Definition
We use the double arrow to indicate that a reaction is reversible. Meaning that both the forward and reverse reactions occur simultaneously.
Term
Rates of chemical reactions
Definition
every reaction has a rate(speed) at which it proceeds. the study of reactant rates is called chemical kinetics.
Reaction rate is variable and depends on the concentration of the reactant species, the temperature, the presence of catalysts, and the nature of the reactants.
Term
A collision between A & B is necessary for a reaction to occur. The rate at which A & B collide is dependent on the concentration of A & B molecules (# of them). It is fastest when they are first mixed. As the reaction proceeds, the number of A & B molecules available for the reaction decreases, there for the reaction rate decreases....RED LINE
Definition
Term
If the reaction is reversible, the speed of the reverse reaction is zero at the beginning and gradually increases as the concentrations of C & D increase from the forward reaction...BLUE LINE
Definition
Term
Equilibrium represents a dynamic state in which two or more opposing processes are taking place at the same time and at the same rate...PURPLE LINE
Definition
Term
when the forward reaction rate is equal to the reverse reaction rate,the reaction is in a state of chemical equilibrium.
This Doesn't mean 100% ionization though.
Definition
Term
LeChatelier's Principle
Definition
States that if a stress is applied to a system in equilibrium, the system will respond in such a way as to relieve the stress and restore its equilibrium under a new set of conditions.
Term
equilibrium constants
Definition
For a reverse reaction at equilibrium, the concentration (aq)/pressure (g) of reactant and products are constant. At euqilibrium, the rates of forward and reverse reactions are equal.
At a given temperature, each reaction has an equilibrium constant associated with these pressures/concentrations.
Term
Keq=(C)^c(D)^d/(A)^a(B)^b
Products over reactants, each raised to the power of the coeff.
If K is large it means you have a lot of Product so it is a product favored reaction. (K is unitless)(only put in aq & g)
the equilibrium will shift after a stress is added in order to maintain its constant.
Definition
Term
Effects of Equilibrium
Definition
1. Concentration: add=shift away; remove=shift towards
2. Pressure/Volume: when the volume decreases the pressure increases so it will increase the concentration of gas making it shift to side with less moles.
If the volume is increased then the pressure decreases and so does the concentration making it shift toward the side with more moles of gas.
3. Temperature:
Endothermic(requires heat): delta H is positive=heat is a reactant.
Exothermic(give off heat): delta H is negative=heat is a products
so
increase of temp=shift away from heat
decrease of temp=shift towards heat
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