sign up I login
 advanced
refer a friend - earn nickels!!

Ask & Discuss Questions with Community & Experts

Moderation Team
 90 chars left    advanced
Ask iit jee aieee pet cbse icse state board community Community Discussion Question: Chemical Kinetics Problems
Forum Index -> Physical Chemistry like the article? email it to a friend.  
Author Message
thegreateye (25)

Cool goIITian

Olaaa!! Perrrfect answer. 3  [8 rates]

thegreateye's Avatar

total posts: 67    
offline Offline

Q1) The activation energy of the reaction: 2HI (g) --------> H2 + I2 is 209.5 KJ/mol. Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy.


Q2) The half life for radioactive decay of 14   C is 5730 years. A sample had 80%  14C . Estimate the age of the sample.


Q3)The rate constant for the decomposition of hydrocarbons is 2.418 * 10-5  at 546 K. If the energy of activation is 179.9 kJ/mol, what is the value of pre-exponential factor.


Q4)The decomposition of A into product has value of k as 4.5 * 103 /s at 10 degrees celsius and energy of activation 60 kJ/mol. At what temperature would k be 1.5 8 104 /s.


pls explain


thnx

    
netkid07 (2019)

Blazing goIITian

Olaaa!! Perrrfect answer. 361  bad job dude!! I dont approve of this answer! 2  [472 rates]

netkid07's Avatar

total posts: 696    
offline Offline
q1---

fraction of molecules of reactants having energy equal to or greater than activation energy= e^(-E/RT)

put the values n get the answer

q3---

k=Ae^(-E/RT)

k=2.418 * 10^-5

E=179.9 kJ/mol

T=546 K

R=0.0821

now put these values and get the value of A

hope it helps...

Who says nothing is impossible.

I've been doing nothing for years !!..............


I know KUNG FU KARATE
and 47 other dangerous words.............

 this reply: 15 points  (with Olaaa!! Perrrfect answer.   in 3 votes )   [?]
 
You have to be logged on to rate
  
MUDIT (614)

Blazing goIITian

Olaaa!! Perrrfect answer. 110  [142 rates]

MUDIT's Avatar

total posts: 324    
offline Offline
for the second one. the decay constant of the reaction is ln2/T
where T is the half life of the reaction = 5730 years
so letAo be the initial conc of carbon in the sample and At be the final so At = 0.8Ao and so usin that formula
ln(Ao/0.8Ao)=(ln2/5730)t
and so t comes out to be round abt 1910 years
please correct me if i am wrong or nudge me if you have any doubts

FAILURE, THE FIRST STEP TO SUCCESS
 this reply: 0 points  (with Olaaa!! Perrrfect answer.   in 0 votes )   [?]
 
You have to be logged on to rate
  
deedee (2203)

Blazing goIITian

Olaaa!! Perrrfect answer. 365  [554 rates]

deedee's Avatar

total posts: 1152    
offline Offline

fpr d last one


log (k2/k1)=Ea/(2.303R)*(T2 - T1/t2*t1)


here substitue k1 as d given value


and k2 we wanna find hope it helps


don't walk as if u rule d world
walk as if u dont care who rules d world

-this is knw as attitude



B who u r and say wat u feel ......
coz those who mind don't matter ........
and those who matter dont mind ......... :)


 this reply: 0 points  (with Olaaa!! Perrrfect answer.   in 0 votes )   [?]
 
You have to be logged on to rate
  
MUDIT (614)

Blazing goIITian

Olaaa!! Perrrfect answer. 110  [142 rates]

MUDIT's Avatar

total posts: 324    
offline Offline

4 pretty same asw the third one

use the equation k=Ae^-E/RT

so for the process occurin at different temperature energy of activation will remain the same

k1=Ae^-E/RT1

k2=Ae^-E/RT2

so k1/k2=e^(E/R)(1/T2-1/T1)

so let k1=4.5*10^3

T1=283K

k2=1.5*10^4

T2=?

E=60kJ/mol=60000J/mol

solve and calculate the ans

it is a little lengthy calculation but if you have any doubts then please feel free to ask


FAILURE, THE FIRST STEP TO SUCCESS
 this reply: 2 points  (with Olaaa!! Perrrfect answer.   in 1 votes )   [?]
 
You have to be logged on to rate
  
MUDIT (614)

Blazing goIITian

Olaaa!! Perrrfect answer. 110  [142 rates]

MUDIT's Avatar

total posts: 324    
offline Offline
ans to 4th one comes to 297.62K or 24.62C

FAILURE, THE FIRST STEP TO SUCCESS
 this reply: 10 points  (with Olaaa!! Perrrfect answer.   in 2 votes )   [?]
 
You have to be logged on to rate
  
 
Forum Index -> Physical Chemistry
Go to:   

 Aakash Institute IIT/ AIEEE/ Medical Crash Course
Name  
E-mail  
Phone  
Mobile  
** Hurry. Exclusive goIIT Offer. Limited Seats Only!
available in: New Delhi, Amritsar, Bhatinda, Bokaro, Chandigarj, Dehradun, Guwhati, Hyderabad, Indore, Jaipur, Kanpur, Karnal, Kolkata, Kota, Lucknow, Ludhiana, Mumbai, Noida, Patiala, Patna, Pune, Ranchi, Varanasi
Top Offers for goIITians
Correspondence Courses
Brilliant Tutorials
Narayana Institute
Aakash Institute
Classroom/Crash Courses
Aakash-IITJEE : AIEEE
Aakash-IITJEE : DCE
Aakash-IITJEE : MHTCET
Aakash Institute : AIPMT
Online Test Series
Brilliant Tutorials
Narayana Institute
Aakash Institute
Mahesh Tutorials
AMITY      Sri Chaitanya