Thread: Rate Laws
View Single Post
disneychannel
#1
Nov21-09, 03:56 PM
P: 52
The first-order decomposition of a colored chemical species, X, into colorless products is monitored with a spectrophotometer by measuring changes in absorbance over time. Species X has a molar absorptivity constant of 5.00 x 10^3 cm^ -1 M^ -1 and the path length of the cuvette containing the reaction micture is 1.00 cm. The data from the experiment are given in the table below.
[X] Absorbance Time(min)
(M)

? 0.600 0.0
4.00 x 10^ -5 0.200 35.0
3.00 x 10^ -5 0.150 44.2
1.5 x 10^ -5 0.075 ?

a) calculate the initial concentration of the colored species.
- I got 1.2 * 10 ^ -4 is that right?

b) calculate the rate constant for the first-order reaction using the values given for concentration and time. Include unites with your answer.
- I got 0.0314, however I do not know if this is correct and will the units be cm ^ -1 M ^ -1

c) calulate the number of minutes it takes for the absorbace to drop from 0.600 to 0.075
how do you do this?
d) calculate half-life of the reation. Include units with your answer.
e) http://www.collegeboard.com/prod_dow...-chem-0607.pdf
question # 3

I WOULD REALLY APPRECIATE if you help me out, it is really confusing!

THANKS!
Phys.Org News Partner Chemistry news on Phys.org
Mineral magic? Common mineral capable of making and breaking bonds
Seeing is bead-lieving: Scientists create model 'bead-spring' chains with tunable properties
New molecule puts scientists a step closer to understanding hydrogen storage