Advertisements
Advertisements
Question
Calculate the half-life of a first order reaction from the rate constant given below:
200 s−1
Advertisements
Solution
For a first-order reaction,
Half life (t1/2) = `0.693/k`
= `0.693/200`
= 3.46 × 10−3 s
RELATED QUESTIONS
Derive the relation between half life and rate constant for a first order reaction
A first order reaction takes 23.1 minutes for 50% completion. Calculate the time required for 75% completion of this reaction.
(log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)
A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.
(log 2 = 0.3010)
The half-life for radioactive decay of 14C is 5730 years. An archaeological artifact containing wood had only 80% of the 14C found in a living tree. Estimate the age of the sample.
The rate constant for the first order decomposition of H2O2 is given by the following equation:
log k = 14.34 − 1.25 × 104 K/T
Calculate Ea for this reaction and at what temperature will its half-period be 256 minutes?
Which among the following reactions is an example of a zero order reaction?
a) `H_(2(g)) + I_(2(g)) -> 2HI_(g)`
b) `2H_2O_(2(l)) -> 2H_2O_(l) + O_(2(g))`
c) `C_12H_22O_(11(aq)) + H_2O_(l) -> C_6H_12O_(6(aq)) + C_6H_12O_(6(aq))`
d) `2NH_(3g)` `N(2g) + 3H_(2(g))`
The half-life period of zero order reaction A → product is given by
(a) `([A]_0)/k`
(b) `0.693/k`
(c) `[A]_0/(2k)`
(d) `(2[A]_0)/k`
Show that the time required for 99% completion is double of the time required for the completion of 90% reaction.
Define half life of a reaction.
Show that for a first order reaction half life is independent of initial concentration.
The half life of the homogeneous gaseous reaction \[\ce{SO2Cl2 -> SO2 + Cl2}\] which obeys first order kinetics is 8.0 minutes. How long will it take for the concentration of SO2Cl2 to be reduced to 1% of the initial value?
Observe the graph shown in figure and answer the following questions:

Write the relationship between k and t1/2 (half-life period)
A sample of U238 (half-life = 4.5 × 109 years) ore is found to contain 23.8 g of U238 and 20.6 g of Pb206. The age of the ore is ______ × 109 years.
The amount of C-14 isotope in a piece of wood is found to be 1/16th of its amount present in a fresh piece of wood. The age of wood, half-life period of C-14 is 5770 years, is ______ years.
Assertion (A): The half-life of a reaction is the time in which the concentration of the reactant is reduced to one-half of its initial concentration.
Reason (R): In first-order kinetics, when the concentration of reactant is doubled, its half-life is doubled.
Obtain a relation, `k_2/k_1 = ((t_(1/2))_2)/((t_(1/2))_1)`, where k1 and k2 are rate constants while (t1/2)1 and (t1/2)2 are half-life periods of the first order reaction at temperatures T1 and T2 respectively. Write the relation for activation energy.
The half-lives of a first-order reaction are 1.19s at 313 K and 15.45s at 293 K. Calculate the energy of activation.
Show that the half-life of zero order reaction is `t_(1/2) = ([A]_0)/(2k)`.
A first order reaction takes 40 min for 30% decomposition. Calculate t1/2.
