Question

sucrose decomposes in acid solution into glucose and fructose according to first order rate law ,with t half 3hours.what is fraction of sample of sucrose remains after 8hours

Answer 1

For a first order reaction,

k = 2.303/t  Log  [R]º / [R]

It is given that, t1/2 = 3.00 hours

Therefore, k = 0.693 / t1/2

= 0.693 / 3  h-1

= 0.231 h - 1

Then, 0.231 h - 1 = 2.303 / 8h  Log  [R]º / [R]

Hence, the fraction of sample of sucrose that remains after 8 hours is 0.158.

Answer 2

For a first order reaction,

k = 2.303/t  Log  [R]º / [R]

It is given that, t1/2 = 3.00 hours

Therefore, k = 0.693 / t1/2

= 0.693 / 3  h-1

= 0.231 h - 1

Then, 0.231 h - 1 = 2.303 / 8h  Log  [R]º / [R]

Hence, the fraction of sample of sucrose that remains after 8 hours is 0.158.