reaction kinetics

Question 1

what is the rate constant k

Answer 1

the proportionality constant in the rate eqn at a given temperature

(k changes with temp and Ea)

Question 2

what is the half life of a reaction and what are the formulas to calculate half life

Answer 2

time taken for the concentration of a reactant to fall to half its value

*constant for 1st order rxn
for 1st order rxn:
t1/2 = (ln 2)/k

for pseudo 1st order rxn (when [A]»>[B])
t1/2 = (ln 2)/k’, where k’ = k[A]

to calculate number of half life elapsed
[A1]/[A2] = (1/2)^n

Question 3

how does conc/temp/catalyst affect rate of rxn?

Answer 3

1) higher conc, particles are closer
higher temp, particles gain kinetic energy
catalyst provides alternative pathway for rxn w lower Ea

2) (only for temp and catalyst) increases the number of particles having energy greater than or equal to Ea

3) frequency of effective collision invreases

4) rate of rxn increases

Question 4

what are the different types of catalysts?

Answer 4

• heterogenous catalysts
• homogenous catalysts
• autocatalysts
• biological catalysts (enzymes)