4.32 numerical plz

Asked by lovemaan5500 | 18th Sep, 2019, 10:02: PM

Expert Answer:

50% of reaction gets completed in 2 hr. that is, half life period of reaction is 2 hr.
 
Next half reaction gets completed in 2hr that is (25% half of reamaining 50%) half life period is 2 hr.
 
So the half life period of reaction is independent of concentration. Hence it is first order reaction.
 
 
Also, we can solve this by using equations for first order reaction,
 
We have,
 
straight t subscript bevelled 1 half end subscript space equals space fraction numerator 0.693 over denominator straight k end fraction
We know, 
 
t1/2 = 2 hr
 
therefore k = 0.3465 hr−1 
 
By using expression for first order reaction,
 
 straight k space equals fraction numerator 2.303 over denominator straight t end fraction cross times log open parentheses fraction numerator straight A over denominator straight A minus straight X end fraction close parentheses
t = 4 hr
 
A = 100
 
(A-X) = 100- 75
 
         = 25 
 
straight k equals fraction numerator 2.303 over denominator 4 end fraction cross times log 100 over 25

straight k equals 0.3466 space hr to the power of negative 1 end exponent
 
By using expressions for first order reaction, we get same value of rate constant.
 
Hence it is confirmed that, it is a first order reaction.

Answered by Varsha | 19th Sep, 2019, 01:12: PM