How fast

Question 1

describe the iodine clock experiment

Answer 1

H2O + 2H+ + 2I——- 2H2O
add sodium thiosulfate and starch (acts as an indicator) to excess hydrogen peroxide
sodium thiosulfate reacts immediately
when no sodium thiosulfate is left to react it then reacts with starch which gives a deep blue colour

Question 2

what is the rate equation

Answer 2

rate is k(A)^(B)^b
rate is in moldm-3s-1
small numbers are orders of the reaction
big letters are conc of substance

Question 3

what does zero order mean

Answer 3

changes in the concentration has no effect on rate

Question 4

what does 1st order mean

Answer 4

changes in concentration has a proportional effect on rate

Question 5

what does 2nd order mean

Answer 5

changes in conc has a squared proportional effect (if conc doubles then rate quadruples)

Question 6

draw a first order rate concentration graph and a concentration time graph

Question 7

draw zero order rate concentration graphs and concentration time graphs

Question 8

draw a 2nd order rate concentration graph and concentration time graph

Question 9

what is half life

Answer 9

the time taken for half of the reactant to be used up

Question 10

half life is independent of conc. so each half life will be ______

Answer 10

the same length

Question 11

what calculation uses half life to calculate rate

Answer 11

k= ln2/t^1/2 units= s^-1

Question 12

what is the rate determining step

Answer 12

the slowest step in a multi-step reaction, determines the whole reaction rate

Question 13

label Arrhenius equation

Answer 13

k=rate constant
A= Arrhenius constant
e= exponential
-Ea= activation energy (j)
R= gas constant 8.314
T= temperature in kelvin

Question 13

what does Arrhenius equation link

Answer 13

activation energy and temperature to the rate constant