Rates Flashcards
definition of rate of reaction? what are the units?
the amount of product formed per unit volume per unit time (mol dm-3 s-1)
what is the rate equation?
Rate=k[A]0[B]1[C]2
describe first order
if [B] is changed, the rate is changed by the same amount (directly proportional on a graph)
how do you calculate overall order?
simply add up all the orders
describe second order
if [C] is changed, the rate is changed by a squared relationship (curve on a graph)
describe zero order
if [A] is changed, rate is unaffected (straight horizontal line on a graph)
how can you find out the order of a reaction?
plot a graph of rate against [concentration] and analyse the shape
what practical’s are done to determine rate?
disappearing cross (initial), gas syringe (continuous), iodine clock
how do you rearrange to find k?
rate/[A][B][C]
what are units the same for?
k and rate
how do you determine k from a graph if first order?
find the gradient as k would be m in y=mx+c OR use half life
definition of half life
the time taken for the concentration of a reactant to decrease to half its original value
when are concentration-time graphs used?
for continuous monitoring methods
how do you use half life to determine an order?
a constant half life indicates first order (use any two)
what is the equation to find k from half life?
k=ln2/half life value
