Advertisements
Advertisements
प्रश्न
In a first-order reaction A → B, 60% of a given sample of a compound decomposes in 45 mins. What is the half-life of reaction? Also, write the rate law equation for the above first-order reaction.
60% of the reactant decomposes in 45 minutes in a first order reaction. Calculate the half life period of the reaction. Write the relation between half life period and initial concentration for zero order reaction.
उत्तर
Given:
[A]0 = 100%
[A]t = 100 − 60 = 40%
t = 45 min
To find: Half life of reaction (t1/2)
Formula: k = `2.303/"t" log_10 ["A"]_0/["A"]_"t"`
Calculation: Substitution of these in above
k = `2.303/"t" log_10 100/40`
= `2.303/(45 "min") log_10 (2.5)`
= `2.303/(45 "min") xx 0.3979`
= 0.0203 min-1
For a first-order reaction, the half-life formula is:
`"t"_(1/2) = 0.693/"k"`
= `0.693/(0.0203 "min"^-1)`
= 34 min
∴ The half life of reaction is 34 min.
Relation between half life and initial concentration for zero-order reaction
`"t"_(1/2) = [A]_0/"2k"`
In first-order reactions, the half-life of a zero-order reaction is directly proportional to the initial concentration.
संबंधित प्रश्न
Choose the most correct option.
The order of the reaction for which the units of the rate constant are mol dm-3 s-1 is _______.
Choose the most correct option.
Slope of the graph ln[A]t versus t for first-order reaction is _________.
Choose the most correct option.
The elementary reaction \[\ce{O3_{(g)} + O_{(g)} -> 2O2_{(g)}}\] is ___________.
Choose the most correct option.
Rate law for the reaction, \[\ce{2NO + Cl2 -> 2NOCl}\] is rate = k[NO2]2[Cl2]. Thus of k would increase with _____________.
Answer the following in one or two sentences.
For the reaction,
\[\ce{CH3Br_{(aq)} + OH^-_{ (aq)} -> CH3OH^-_{ (aq)} + Br^-_{ (aq)}}\], rate law is rate = k`["CH"_3"Br"]["OH"^-]`
What is the change in rate if concentrations of both reactants are doubled?
The rate law relates to the rate of a chemical reaction in terms of _______.
For the reaction \[\ce{2NO_{(g)} + 2H_{2(g)} -> N_{2(g)} + 2H2O_{(g)}}\],
The rate law is, rate = k[NO]2 [H2].
What is the overall order of reaction?
Define order of reaction with suitable examples.
A reaction occurs in the following steps:
Step 1: \[\ce{NO_{2(g)} + F_2 -> NO2F_{(g)} + F_{(g)}}\] (slow)
Step 2: \[\ce{F_{(g)} + NO_{2(g)} -> NO_2F}\] (Fast)
- Write the equation of overall reaction.
- Write the rate law.
- Identify reaction intermediate.
The rate constant of a first order reaction whose half-life is 480 seconds, is ____________.
For the reaction, \[\ce{N2(g) + 3H2(g) -> 2NH3(g); \Delta H}\] is equal to ______.
A gaseous hypothetical chemical equation \[\ce{2A ⇌ 4B + C}\] is carried out in a closed vessel. The concentration of B is found to increase by 5 × 10−3 mol dm−3 in 10 second. The rate of ____________.
For a hypothetical reaction \[\ce{A + B -> C}\], it is found that doubling the concentration of A increases the rate by 8 times and doubling the concentration of B increases the rate by 4 times. The overall order of the reaction is ____________.
The order of the reaction occurring by following mechanism should be:
(i) \[\ce{A2 + B2 -> AB2 + A (slow)}\]
(ii) \[\ce{A + B2 -> AB2 (fast)}\]
The rate law for the reaction \[\ce{A + B + C -> Product}\] is expressed as Rate = k[A]2 [B]1 [C]0. What is the overall order of the reaction?
Consider the reaction \[\ce{2A + 2B -> C + 2D}\], if concentration of A is doubled at constant [B], rate increases by a factor 4. If concentration B is doubled at constant [A] the rate is doubled. Rate law of the reaction is ____________.
In the reaction \[\ce{A + B2 -> AB + B}\], the rate of reaction is directly proportional to the concentration of A and independent on the concentration of B2. What is the rate law expression?
The reaction \[\ce{A + B -> P}\], is second order in A and first order in B. What is the rate law for the reaction?
In the reaction, \[\ce{N2 + 3H2 -> 2NH3}\], the rate of disappearance of H2 is 0.02 Mis. The rate of appearance of NH3 is ______.
In the reaction \[\ce{2SO_{2_{(g)}} O_{2_{(g)}} -> 2SO_{3_{(g)}}}\], the rate of disappearance of SO2 is 1.28 × 10-5 M/s. What is the rate of appearance of SO3?
For the reaction \[\ce{4NH3 + 5O2 -> 4NO + 6H2O}\], the rate of disappearance of NH3 is 3.6 × 10-3 M/s. What is the rate of formation of water?
Which of the following statement is not true for a reaction having rate law r = k[H2][I2]?
Write the rate law for the following reaction:
A reaction that is zero order in A and second order in B.
Write the rate law for the following reaction:
A reaction that is second order in NO and first order in Br2.
For the reaction A + B → P.
If [B] is doubled at constant [A], the rate of reaction doubled. If [A] is triple and [B] is doubled, the rate of reaction increases by a factor of 6. Calculate the rate law equation.
