hymie

a first order reaction has a fifth life of 20 seconds ( the amount of time needed to use up 1/5) a) Prove that the reaction has a constant 1/5 life. b) find the half life.

oh i see 1/5 times 80 is 16 so that is the fifth life of the rxn. for the half life usage should i take 50 seconds using the convenient number of 100 seconds?

how did you get 80 - 16?

when i chose the next interval of a fifth i did 64 x 1/5 = 12.8 and then i took ln(64/12.8) and that did not give me the same constant as the first two so does this mean that the fifth life is not constant

i think you made a mistake in the first answer you take ln(100/20) not 100/80 then it will prove it has a constant fifth life