Chapter 14 Kinetics and rates of reactions Flashcards
rate of reaction
the rate at which a reaction occurs, measured in M/s`
what are rates measured for in chemical reactions
concentration per second
N2 + O2 = 2NO
rate expressed in N2
-delta N2/deltat
N2 + O2 = 2NO
rate expressed in NO
1/2(deltaN0)/deltaT
are the products or reactants negative and why
the reactants are negative because they are consumed
average rate of reactons
the average rate over a given time
3 things that affect reaction rates
concentration
temperatures
structures and orientations
general formula for the rate of a reaction
1/a(delta molecule)/delta t
-if the molecule is a reactant than the whole system is negative
concentration and the rate of reaction
if concentration increases then the rate increases
temperature and the rate of reaction
if the temperature increases than the rate of reaction increases
structure and orientation of colliding particles
ASK
given a graph of concentration over time
asked for the average rate of reaction between 2 times
-(concentration t2 - concentration t1)/(t2-t1)
given the concentration vs time graph can you use either products or reactants
yes jsut make sure to watch negatives and use the 1/a coefficient strat
calculate the instantaneous rection rate gioven the graph or a chart of time and concentration
basiacally take the average which will get you the slop at the point, usually the 2 adjacent points
rate law
rate = k[a]^n k = constant a = molecule n = reaction order
reaction orders can be
whole numbers or fractions
how to find the reaction order given a chart of concentrations and rates
- set it up as rate2/rate1 = k[a2]^n/k[a1]^n
- use algebra to solve for n
- take the log of both sides and use log properties for the exponent
can a reaction have more than 1 reaction order
yes. it can be entirely respective to the molecule
if the temp increaseses what happens to k
it also increases
given the rate of a reactant find the rate of the product
use stoich to transfer the rate
given the rate of a species in the reaction, find the rate of the entire reaction
find the rate as it is for a species with a coefficient of 1
describe the graphs of the different orders of reacions
0 flat
1 line angled
2 curved
how to find the rate constant k after solving for the reaction order
plug in eberything and solve for k
effect of temp on rates of reactions
as temp increases so does the rate
arrhenius equation
k = A*e^(-(Ea/RT))
k
gass constant
T
temp
Ea
energy of activation(an energy barrier that must be surmounted for a reaction to take place)
A
frequency factor( number of times the reactants approach the activation barrier per unit time
