Question

A first order reaction is 20% completed in 10 min in how much time it will be 75% complete approximately

Answer 1

Answer:

Explanation:

We known that time period for 1 St order reactions is

T = -2.303 log(final concentration/initial concentration)/k

For given reaction we need to find k

Now

initial concentration A = 100

Final concentration B = 80

And time T = 10 min

So

k = -2.303 log (B/A) /T

=-2.303 log(80/100) / 10

=0.0223

Therefore k = 0.0223.

For new reaction

Final concentration C = 25 ( because 75 of reaction is finished).

Now

time taken T = -2.303 log(C/A)/k

= -2.303 log(25/100) /0.0223

=62.17 min

Therefore time taken to complete 75% of reaction is 62.17 min.