Advertisements
Advertisements
प्रश्न
What is half life of first order reaction if time required to decrease concentration of reactants from 0.8 M to 0.2 M is 12 hours?
Advertisements
उत्तर १
Given: [A]0 = 0.8 M, [A]t = 0.2 M, t = 12 hours
To find: Half life of reaction (t1/2)
Formulae:
- k = `2.303/"t" log_10 (["A"]_0)/(["A"]_"t")`
- `"t"_(1/2) = 0.693/"k"`
Calculation: Substituting given value in
k = `2.303/"t" log_10 (["A"]_0)/(["A"]_"t")`
k = `2.303/(12 "hr") log_10 0.8/0.2`
= `2.303/(12 "hr") log_10 (4)`
= `2.303/(12 "hr") xx 0.6020`
= Antilog10 (log10 2.303 + log10 0.6020 − log10 12)
= Antilog10 (0.3623 + `bar(1).7796` − 1.0792 )
= Antilog10 `(bar(1).0627 )`
= 0.1115 hr–1
`"t"_(1/2) = 0.693/"k" = 0.693/(0.1155 "hr"^-1)` = 6 hr
उत्तर २
Concentration is reduced to 25%. It means it takes two half-lives to decrease the concentration of reactant from 0.8 M to 0.2 M in first-order reaction. Hence, half-life of the reaction is 12/2 = 6 hours.
The half life of reaction is 6 hours.
APPEARS IN
संबंधित प्रश्न
Write a mathematical expression for integrated rate law for zero-order reaction.
Explain pseudo first order reaction with a suitable example.
Derive an integrated rate law expression for first order reaction: A → B + C
For a first-order reaction, the rate constant is 6.909 min−1 the time taken for 75% conversion in minutes is
The rate constant of a reaction is 5.8 × 10−2 s−1. The order of the reaction is ____________.
Identify the order for the following reaction.
Radioactive disintegration of 92U238
The time for half change in a first order decomposition of a substance A is 60 seconds. Calculate the rate constant. How much of A will be left after 180 seconds?
A zero order reaction is 20% complete in 20 minutes. Calculate the value of the rate constant. In what time will the reaction be 80% complete?
A first order reaction is 40% complete in 50 minutes. Calculate the value of the rate constant. In what time will the reaction be 80% complete?
What is the value of rate constant of first order reaction, if it takes 15 minutes for consumption of 20% of reactants?
How long would it take to electroplate a spoon with 0.1 mol of silver (108 g/mol) at a constant current of 2.0 A using AgNO3?
The rate of the reaction \[\ce{A + B -> C}\] is 3.6 × 10−2 mol dm−3 s−1 when [A] = 0.3 mol dm−3 and [B] = 0.2 mol dm−3. Calculate k if reaction is first order in A and zero order in B.
A reaction that is of the first order with respect to reactant A has a rate constant 6 min−1. If we start with [A]0 = 0.5 mol dm−3, when would [A] reach the value 0.05 mol dm−3?
In a first order reaction, the concentration of the reactant, decreases from 0.8 mol dm−3 to 0.4 mol dm−3 in 15 minutes. The time taken for the concentration to change from 0.1 mol dm−3 to 0.025 mol dm−3 is ____________.
The rate and the rate constants of the reaction, \[\ce{A + 2B -> C + D}\] are 8 × 10−3 mol dm−3 s−1 and 2 × 10−3 s−1 respectively. The concentrations of A and B are 4 mol dm−3 each. The overall order of the reaction is ____________.
Half-life period of a first order reaction, \[\ce{A -> product}\] is 3.0 hours. What is the value of rate constant?
Reaction given below follows first order kinetics:
\[\ce{2N2O2 -> 4NO2 + O2}\]
Calculate the rate constant of reaction if concentration of N2O2 is 0.05 M and rate of reaction is 1.5 × 10−6 mol L−1 s−1?
The slope of a graph, log [A]t versus 't' for a first order reaction is −2.5 × 10−3 s−1. The rate constant for the reaction is ____________.
Which among the following is an example of zero order reaction?
A first order reaction takes 40 minutes for 30% decomposition. What is the half-life of reaction?
In a reaction \[\ce{N2_{(g)} + 3H2_{(g)} -> 2NH3_{(g)}}\], if the rate of disappearance of N2(g) is 2.6 × 10−4 M/s, the rate of disappearance of H2(g) in M/s is ____________.
For the first order reaction A → B, the rate constant is 0.25 s-1, if the concentration of A is reduced to half, the value of rate constant will be ________.
What is the unit of rate constant for the zero order reaction?
Which is the unit of rate constant for the first-order reaction if time is expressed in seconds?
The integrated rate equation is Rt = log C0 – log Ct, then the straight-line graph is obtained by plotting.
The rate constant for a first order reaction is 7.0 × 10-4 s-1. If initial concentration of reactant is 0.080 M, what is the half-life of reaction?
Which is the relation between half life and rate constant for a zero order?
The half-life period for the first order reaction is 1.7 hrs. How long will it take for 20% of the reactant to disappear?
