Rate equations Flashcards
For the following reaction aA + bB -> products what is the generalised rate equation
r = k[A]m[B]n
rate units
moldm-3 s-1
What do square brackets symbolise?
concentration
what is k called?
the rate constant
In the rate equation r = k[A]m[B]n , what are the m and n called?
reaction orders
Total orders=
adding all individual orders
Zero order A means it has what effect on the rate of reaction?
r= k[A]0
no effect
First order A means it has what effect on the rate of reaction?
r = k[A]1
directly proportional to concentration of A
Second order A means it has what effect on the rate of reaction?
r = k[A]2
proportional to concentration of A^2
1st order overall reaction k units?
s-1
2nd order overall reaction k units?
mol-1 dm3 s-1
3rd order overall reaction k units?
mol-2dm6s-1
k’s value is independent of
concentration and time
constant at a fixed temperature (if temp increases, k increases)
how to calculate k?
rearrange rate equation for k as a subject
indices in rate equations are not …
stoichiometric values
Initial rate on a concentration vs time graph?
gradient at 0
Different volumes of the same initial concentrations will have the _____ initial rate if other conditions are the same but _____
the same
will end at different amounts
Make the rate equation rate = k[y]n into a y = mx+ c equation
log both sides of the eqn
lograte = logk + nlog[Y]
y = c + mx
Deducing rate equation from experiment data
compare between reactions where a reactant conc hasn’t changed
use this value if the others all change after
Arrhenius equation
k = Ae^–Ea/RT
lnk (arrhenius equation) =
y = mx + c components:
-Ea/RT + ln A
gradient = 1/T
m = -Ea/R (/1000 for Ea)
c = ln A
