2.Rates of reaction Flashcards
define rate of reaction
the rate of change of concentration of a reactant or product per unit time
unitis of rate?
mol dm-3 s-1
initial rate of reaction?
the change in conc of a reactant or product at the strat of a reaction wehn t=0
examples of things to measure to get rate?
- ph
- volume/pressure
- loss of mass
- colour change
- temp change
what is the rate equation?
for reaction A+B->C
rate=k[A]m[B]n
m+n=overall order
what is the order?
the power to which the conc of a reactant is raised to in the rate equation.
what is overall order?
the sum of the individual orders in a reaction
what is the rate constant?
the constant that links the rate of reaction with the concs of reactants raised to the powers of their orders in the rate equation.
how can rate equation be determined?
only from experimental data
factors that effect rate constant?
- temp
- catalyst
- Surface area
(not concentration)
what is the half life?
time taken for the rectant concentration to redude by half.
half life in a 0 order?
half life decreases, as rate is constant but less [conc] is used.
half life is a 1st order?
half life is CONSTANT, decreased rate and decreased [conc]
half life in a 2nd order?
half life increases, as rate is decreasingby [conc]2 and conc decreasing by [conc] .
what is the rate determining step?
The slowest step in the reaction mechanism of a multi step reaction.
Governs the whole reaction.
(that speaps rate equation determins the overall rate equation)
