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प्रश्न
If the half-life period for a first-order reaction is 69-3 seconds, what is the value of its rate constant?
उत्तर
If the half-life of the first-order reaction is T, then its rate constant,
`K = 0.693/T = 0.693/69.3 = 0.01 `sec-1
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संबंधित प्रश्न
Complete the following statement by selecting the correct alternative from the choices given:
The half-life period of a first-order reaction is 20 minutes. The time required for the concentration of the reactant to change from 0.16 M to 0.02 M is:
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
(first, zero, twice, lanthanoid, iron, copper, yellow, blue, benzophenone, transition)
The half-life of a ______ order reaction is independent of the initial concentration of reactants. For a first-order reaction, the time required for 75% completion is ______ the half life time.
For a first order reaction, the half-life period (t1/2) is ______.
Read the passage carefully and answer the questions that follow.
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A plant or any other living being maintains a reasonable balance of C-14 (radioactive carbon) in its tissue during its lifetime. C-14 is used to determine the age of fossils. In the upper atmosphere, neutrons present in the cosmic rays are captured to produce the following nuclear reaction. \[\ce{_7N^14 + _0n^1 -> _6C^14 + _1H^1}\] C-14 isotope circulates in the atmosphere and is absorbed by living organisms during photosynthesis. The ratio of C-14 to C-12 in living beings is 1 : 1012. Once a living being dies, the level of C-14 in the dead being decreases due to the following reaction. \[\ce{_6C^14 -> _7N^14 + _-1e^0 + γ rays}\] The death of the plant brings an end to its tendency to take up C-14. The half-life period of C-14 is 5770 years. By knowing the concentration of C-14 in the living plant and the piece of dead material at a particular time, the age of the material (fossil) can be determined. |
- Write the relation between the decay constant and half-life period.
- In a piece of dead wood, the activity or concentration of C-14 is found to be one third of its initial activity. Calculate the age of the old wood.
- The half-life period (t1/2) for a first order reaction is 30 minutes. Calculate the time taken to complete 87·5% of the reaction.
