Question

If rate constant for a 1st order reaction is k, then T1/4 can be written as: 0.29/k.

I know, that k=0.693/T1/2, where k=> rate const. and T1/2=> half life.

T1/4 is twice half-life.

How do you get the given answer?i.e 0.29/k.

Answer 1

T (1/4) = [ln (1/(1-0.25))] /k
= ln (4/3) x 1/k
= 0.285/k

Answer 2

How can i use T1/2 = 0.693/k, without using logs.

Answer 3

uve got to use logs even if u break it up like
[ln 4 - ln 3]/k
= 2(ln2)/k -(ln3)/k
the first term u cn use t1/2 but uve gotta use logs for the second term