Question

If a zero order reaction completed to 60% in 30 minutes then time in which reaction completed to 80% will be​

Answer 1

Given:

The time taken for zero order reaction to complete 60%, t = 30 minutes

To Find:

The time in which reaction will be completed to 80%.

Calculation:

- After 60% completion, amount left, [R] = 40% of [R]₀ = 0.4 [R]₀

- For zero order reaction:

k = ([R]₀ - [R])/t

⇒ k = ([R]₀ - 0.4 [R]₀)/ 30

⇒ k = 0.6 [R]₀/ 30

⇒ k = 0.02 [R]₀

- Now, when reaction is 80% complete, amount left, [R] = 20% of [R]₀ = 0.2 [R]₀

- Again using the same formula, we get:

k = ([R]₀ - 0.2 [R]₀)/ T

⇒ 0.02 [R]₀ = 0.8 [R]₀/ T

⇒ T = 0.8 /0.02

⇒ T = 40 minutes

- So, the time in which reaction will be completed to 80% is 40 minutes.

Answer 2

Time of 80% completion = 40 minutes

Explanation:

Given: A zero order reaction completed to 60% in 30 minutes.

Find: Time in which 80% reaction is completed.

Solution:

Let the concentration of the reactant initially be x.

Then 60% reaction can be written as: 0.6x = -k *t1 ------(1)

Then 80% reaction can be written as: 0.8x = -k *t2 ------(2)

Dividing (1) by (2), we get:

0.6x / 0.8x = -k *t1 / -k *t2

  3/4 = t1/t2

  3/4 = 30/ t2

Therefore t2 =  4 * 30 / 3 = 40 minutes