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A first order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?
  • a)
    1.26 × 1015 s
  • b)
    2.52 × 1014 s
  • c)
    2.52 × 1028 s
  • d)
     infinite
Correct answer is option 'D'. Can you explain this answer?
Verified Answer
A first order reaction is 50% completed in 1.26 × 1014s. How muc...
The time taken for half the reaction to complete, i.e., the time in which the concentration of a reactant is reduced to half of its original value is called half-life period of the reaction. But it is impossible to perform 100% of the reaction. Whole of the substance never reacts because in every half-life, 50% of the substance reacts. Hence, time taken for 100% completion of a reaction is infinite. 
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A first order reaction is 50% completed in 1.26 × 1014s. How muc...
To determine the half-life of a first-order reaction, we can use the equation:

t1/2 = (0.693 / k)

where t1/2 is the half-life and k is the rate constant.

In this case, we know that the reaction is 50% completed, which means that the concentration of the reactant has decreased by half.

Since the reaction is first-order, we can use the natural logarithm to solve for the rate constant:

ln(C0 / C) = kt

where C0 is the initial concentration, C is the concentration at time t, k is the rate constant, and t is the time.

Since the reaction is 50% completed, the concentration at time t is equal to half of the initial concentration (C = C0/2).

ln(C0 / (C0/2)) = k(1.26)

ln(2) = 1.26k

Now, we can solve for k:

k = ln(2) / 1.26

k ≈ 0.5513 min^-1

Finally, we can calculate the half-life:

t1/2 = (0.693 / k) = (0.693 / 0.5513)

t1/2 ≈ 1.258 min

Therefore, the half-life of the first-order reaction is approximately 1.258 minutes.
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Community Answer
A first order reaction is 50% completed in 1.26 × 1014s. How muc...
A first order reaction never completes fully
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A first order reaction is 50% completed in 1.26 × 1014s. How much time would it take for 100% completion?a)1.26 × 1015sb)2.52 × 1014sc)2.52 × 1028sd)infiniteCorrect answer is option 'D'. Can you explain this answer?
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