Chapter 18 - Kinetics
No description yet. This curated deck is ready for daily study.
Card preview (21)
what is the rate of reaction defined as
the change in concentration with unit time
when is the initial rate
when t=0
how can you tell that a species is a catalyst from the rate and balanced equations
if it appears in the rate equation but not the balanced equation then it is a catalyst
what condition will change k
temperature
what does a conc against time graph look like for a 0th order reactant and why
linear because over time the concentration changes but the rate does not (the rate is the gradient which is constant)
why can the rate equation only be determined experimentally
because the initial rates need to be measured for a certain reaction at certain conditions
what shape of a rate against concentration graph for 0th, 1st, and 2nd orders
0th is a horizontal line 1st is linear 2nd looks like half a quadratic graph
delete
Delete
what qualitative information does the magnitude of the rate constant K tell you about a reaction
the larger the value of K, the faster the reaction
why does the rate constant depend on temperature only
as temperature increases, a much greater proportion of molecules have enough energy to react so the proportion of successful collisions increases
what are intermediates
species that form during the mechanism of a reaction which then are used to make the products they dont appear in the final balanced equation
what is the rate determining step
the slowest step of a reaction
how do steps before and after the rds affect the rate of reaction
steps after the rds have no effect on the rate so the reactants dont appear in the rate equation steps before the rds do affect the rate and hence their reactants appear in the rate equation
with reference to the mechanism of a reaction, what do the orders in a rate equation tell you about the mechanism
they tell you the stoichiometric ratios in which the reactants of the rds react in
state the significance of 0th order reactants for the mechanism of a reaction
it does not appear in the rds
why does the use of a significant excess of a reactant mean they dont appear in the rate equation
because the concentration of the reactants in excess will not change, thus their concentrations will not affect the rate
what does it mean to quench a reaction and how do you do it
quench means end the reaction and you can do it by diluting the reaction mixture significantly
what is a decomposition step
An elementary step where one molecule breaks up into two is called a decomposition step.
what is a substitution step
An elementary step where two particles collide and form two completely different particles is called a substitution step.
what is a synthesis step
An elementary step where two particles collide and join together as a single particle is called a synthesis step.