MY CART (5)

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price:

There are no items in this cart.
Continue Shopping
                   what is the difference between first order kinetics and pseudo first order kinetics. Is adsorption kinetics is different. Because Iam working in Dye removal studies by algal biomass, which order kinetics should I follow.
                   

3 years ago

Share

Answers : (2)

                                        

Dear Rashmi V,


The main difference between a First Order Reaction & a Pseudo First Order reaction is that the Pseudo first order eaction is a reaction that should actually happen by some higher order(higher than 1) but occurs by first order beacuse the concentration of one reactant used is very high & another reactant used is very low ...


The concentration of the reactant which is very low can be negleted & thus the concentration of the reactant which has higher concentration is alone taken !


This makes the reaction follow a first order kinetics rather than some higher order.This is Pseudo First order reaction !


 


Hope you understood now..


All the Best & Good Luck !


Please approve my answer if you liked it by clicking on "Yes" given below...!!Smile


 

3 years ago
                                        

Pseudo First Order Reaction

A  and  B  react to produce  P:



If the initial concentration of the reactant  A  is much larger than the concentration of  B,   the concentration of  A  will not change appreciably during the course of the reaction The concentration of the reactant in excess will remain almost constant. Thus the rate's dependence on  B  can be isolated and the rate law can be written


Equation  (1)  represents the differential form of the rate law. Integration of this equation and evaluation of the integration constant  C  produces the corresponding integrated law.

Substituting  [ B ]  =  c  into equation  (1)  yields


Integrating equation  (2)  gives: The constant of integration  C  can be evaluated by using boundary conditions. At  t  =  0,   the concentration of  B  is  co.

Therefore Accordingly, equation  (3)  can be rewritten as follows:
If the decrease in concentration of  B  is followed by photometric measurement the  Beer' Law  must be taken into account.

Combining equation  (5)  and  Beer' Law

A  =  Absorbance,  e = Molar absorbtivity with units of  L · mol -1 · cm -1
c  =  Concentration of the absorbing species in solution, expressed in  mol · L -1,  d  =  Path length through the sample
Io =  Intensity of the initial light beam,  I  =  Intensity of the transmitted light

gives the relationship between  k'  and  lnA:



According to equation  (7),  a plot of lnA versus time should lead to a straight line whose slope is the pseudo-first order rate constant  k'.  The value of  k'  can then be divided by the known, constant concentration of the excess compound to obtain the true constant second order  k:


The  pseudo-first order rate constant k'  can be also determined from the  half-life t 1 / 2.



Measuring a second order reaction rate (see below) can be problematic: the concentrations of the two reactants must be followed simultaneously, which is more difficult; or measure one of them and calculate the other as a difference, which is less precise. A common solution for that problem is the pseudo first order approximation. As a general rule, a minimum of a 20-fold stoichiometric excess is necessary. A 50-fold or 100-fold stoichiometric excess is preferable.

3 years ago

Post Your Answer

More Questions On Physical Chemistry

Ask Experts

Have any Question? Ask Experts

Post Question

 
 
Answer ‘n’ Earn
Attractive Gift
Vouchers
To Win!!!
Click Here for details
Which book can be useful for studying IIT physical chemistry?
 
 
You can find here list of good books. Apart from physical chemistry you will find help for other books. http://www.askiitians.com/important-books-iit-jee.aspx
  img
Harsh Patodia one month ago
 
Dr.P.bhadur’s numerical chemistry for good numericals with solutions.
 
Vignesh R one month ago
 
HC VERMA
 
Ch. Sai tejasri one month ago
when 0.1 mole of ammonia is dissolved in sufficient water to make 1 litre of solutionThe solution is found to have a hydroxide ion conc of 1.34 * 10 power -3.The dissociation const of...
 
 
Dear student, please put the value of [OH-]=1.34*10 -3 M (Given in the question) Here I did a mistake in putting the value for hydroxide ion.Then the equation will be x+10 -7 M=1.34*10 -3....
  img
Naveen Kumar 7 months ago
 
Molarity of NH3=0.1mole/1Litre=0.1M The raction can be given as : NH3+H2O...........=NH4 + ....+OH- 0.1M.........................0.........10 -7 M (due to water)........initially...
  img
Naveen Kumar 7 months ago
 
sir i didnt get the ans.
 
Shriya Mehrotra 7 months ago
I have these two doubts please help me with these please try to be more explanative
 
 
Let us cosider two molecules of Ethylene. we can think it as we have to break two c-c double bond and we have to form four c-c single bond. Now breaking of bond requires energy(endothermic)...
  img
Naveen Kumar 6 months ago
 
this is a simple question and you can get good things from solving this so just try
 
britto george one month ago
 
thank you
 
Kaustubh Nayyar 5 months ago
What happens when acetone reacts with HgSO4 in HCl instead of Sulphuric acid
 
 
Acetone reacts with HgSO4 in acedic medium and undergoes nucleophilic addition reaction. It results in formation of alochol.
  img
Gaurav 8 days ago
 
it reacts in same way H2SO4 is used because it has high boiling point
 
Shubham Singh 8 days ago
sodium thiosulphate is formed when
 
 
thiosulpahate ion is also used in the iodometric titration
 
akshat yesterday
 
6 NaOH + 4 S → 2 Na 2 S + Na 2 S 2 O 3 + 3 H 2 O approve if useful
 
akshat yesterday
Dative bond is not involved during : a)protonation of ether b)Dissolution of HCl in water c)Dimerisation of benzoic acid d)formation of Be 2 Cl 4
 
 
yeah actually it should be c. becl2 exists as a dimer be2cl4 and hence involves co ordinate bond. dimerization of benzoic acid involves hydrogen bonding
 
sanika muley one month ago
 
co ordinate bond is also known as dative bond. i guess the answer should be (d).
 
sanika muley one month ago
 
ans. given in the book is c.
 
mansi dabriwal one month ago
View all Questions »