Question

For a given order reaction, the half life is 0.5 minute, at a given temperature. Calculate the time needed for

75% of the reactant to decompose.
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Answer 1

Answer:

t = 0.99932 minute

Explanation:

Given = t1/2 = 0.5 minutes

to find= t such that 75% of reactant get decompose

So let us assume at ;

a) t = 0 ⇒ 100% reactant present = [A]o

b) t = x ⇒ 100-75 = 25 % reactant present [A]x

we know that ; k= 2.303/t ㏒[A]o/[A]x

to find k we use the formula ;

for first order reaction : t1/2 = 0.693/k

therefore= k = .693/.5⇒ 1.386

putting the value we get :  t = 2.303/1.386 log[100]/[25]

t = 0.99932 minute