# 25% of First Order Reaction is Completed in 30 Minutes. Calculate the Time Taken in Minutes for the Reaction to Go to 90% Completion. - Chemistry (Theory)

Sum

25% of first order reaction is completed in 30 minutes. Calculate the time taken in minutes for the reaction to go to 90% completion.

#### Solution

t = 30 min
[A]0 = 100
[A]1 = 75

∴ k = (2.303)/tlog  [A]_0/[A]_1

therefore k = 2.303/30 log  100/75
therefore k = 0.076xx0.1249=9.58 xx 10^-3
Now, time requried for 90% completion
t = ?
[A]_0= 100

[A]_1 = 10
k = 9.58 × 10-1
9.58 × 10^-3 =2.303/t  log  100/10
t = 204.39 min

Concept: Meaning of Chemical Kinetics - Scope and Importance of Kinetics of the Reaction
Is there an error in this question or solution?