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A first order reaction is 20% completed in 10 minutes. Calculate the time (in minutes) taken for the reaction to go to 80% completion: [rounded up to two decimal places]
    Correct answer is between '71.80,72.40'. Can you explain this answer?
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    A first order reaction is 20% completed in 10 minutes. Calculate the t...
    Explanation:

    Given, the reaction is a first-order reaction.

    The equation for first-order reaction is,

    ln ([A]t/[A]0) = -kt

    where [A]t is the concentration of reactant at time t, [A]0 is the initial concentration of reactant, k is the rate constant, and t is the time.

    Step 1: Finding the rate constant (k)

    Let's assume the initial concentration ([A]0) to be 100. Then the concentration at 20% completion would be ([A]t) = 80.

    Using the given information, we can write:

    ln ([A]t/[A]0) = -kt

    ln (80/100) = -k(10)

    -0.223 = -10k

    k = 0.0223 min^-1

    Step 2: Finding the time taken for 80% completion

    Now, we need to find the time taken for the reaction to go from 20% to 80% completion, which means the concentration at 80% completion would be ([A]t) = 20.

    Using the same equation as before, we can write:

    ln ([A]t/[A]0) = -kt

    ln (20/100) = -0.0223t

    -1.609 = -0.0223t

    t = 71.8 min (rounded up to two decimal places)

    Therefore, the time taken for the reaction to go to 80% completion is 71.8 minutes (rounded up to two decimal places).
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