A certain first-order reaction a → b is 25% complete in 42 min at 25°c. What is the half-life of the reaction?

First-order reaction is defined as the reaction in which the rate of the reaction is dependent on the concentration of only one reactant.

The half-life of the reaction is 101.6 minutes.

The rate constant for the first-order reaction can be determined by:

In which:

x= amount of reactant decomposed in time t

k= rate constant  

a-x= amount of reactant left after time t

t= time required for a reaction

a= initial concentration

The initial concentration of the reaction is 100.

Now, given:

x = 25

a - x = 75

t = 42

Putting the values in the above equation, we get:

k = 6.85 x 10 ⁻³

The half-life will be:

minutes.

Therefore, the half-life of the reaction is 101.6 minutes.

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link

minutes

Explanation:

For a First order reaction, the rate constant is determined by

Where

k= rate constant

t= time required for a reaction

a= initial concentration

x= amount of reactant decomposed in time t

a-x= amount of reactant left after time t

Let the initial concentration be

Then

Substituting the given values in above equation, we get -

Also,

minutes

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explanation:

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unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.