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33 Cards in this Set
- Front
- Back
rate of a reaction |
change of concentration of prod or react / change in time
negative |
|
rate of product formation |
positive
change of concentration of prod or react / change in time |
|
reactant and product concentration over time |
reactants decrease as products increase |
|
average rate of reaction |
rate slowly decreases over time |
|
rate - k[A]^n |
k= rate constant n = reaction order: 0,1,2 |
|
zero order |
n=0
rate is independent of concentration
(M s) |
|
first order |
n=1
rate is directly proportional to the concentration
(M-1 s) |
|
second order |
n = 3
rate is proportional to the square of the concentration
(M-1 s-1) |
|
reactant concentration vs time graph |
go downwards, getting less linear as order number increases |
|
rate vs reactant concentration graph |
zero order is horizontal first order is diagonal ascending second order is curved, diagonal ascending |
|
overall order |
the sum of all the exponents |
|
integrated rate law |
relationship between concentrations of the reactants and time
depends on order of reaction |
|
half life (t/2) |
the time required for the concentration of a reactant to fall to one half of its initial value |
|
arrhenius equation |
shows the relationship between the rate constant and the temperature in kelvins |
|
activation energy (Ea) |
the energy barrier that must be overcome for the reactants to be transformed into products
downhill: exothermic uphill: endothermic |
|
frequency factor (A) |
number of times that the reactants approach the activation barrier per unit time |
|
activated complex / transition state |
a high-energy intermediate state of the reactants before being formed into products |
|
the higher the activation energy... |
the slower the reaction rate at a given temperature |
|
exponential factor |
is a number between 0 and 1
the fraction of approaches that the reactants approach in actually overcoming the activation barrier and forming products
|
|
exponential factor relationship with temp and activation energy |
increases with increasing temperature
decreases with increasing activation energy |
|
collision model and frequency factor |
depends on orientation to affect collision frequency |
|
orientation factor of individual atoms |
is close to 1 |
|
reaction mechanism |
series of individual chemical steps by which an overall chemical reactions occur |
|
elementary steps |
each step in a reaction
cannot be broken down into simpler ones |
|
reaction intermediate |
forms in one elementary step and is consumed in the other |
|
rate determining step |
the slowest step in the whole reaction, determining the overall rate |
|
catalyst |
increases the rate of a chemical reaction and is not consumed by the reaction |
|
homogenous catalyst |
exists in the same state as the reactants |
|
heterogenous catalyst |
exists in a different state as the reactants |
|
adsporption |
reactants are adsorbed onto the metal surface |
|
diffusion |
reactants diffuse on the surface until they approach each other |
|
reaction |
the reactants react to form products |
|
desorption |
products desorb from the surface into the gas phase |