A first-order reaction is 25% complete in 15 minutes. What is the rate constant?
k = (2.303/15) log(1/0.75) ≈ 0.0192 min⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
Pseudo First Order and Complex Reactions
Practice questions and explanations on pseudo first order reactions and complex reaction mechanisms, including their derivation and real-world applications.
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A first-order reaction is 40% complete in 15 minutes. What is the rate constant?
k = (2.303/15) log(1/0.6) ≈ 0.0341 min⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A first-order reaction is 25% complete in 10 minutes. What is the rate constant?
k = (2.303/10) log(1/0.75) ≈ 0.0288 min⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A first-order reaction has a half-life of 18 minutes. What fraction of the reactant remains after 54 minutes?
3 half-lives → fraction remaining = 1/8.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A first-order reaction has a rate constant of 0.0173 min⁻¹. What is the time for 80% completion?
t = (2.303/0.0173) log 5 ≈ 93 min.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
For a first-order reaction, how many half-lives are required for 75% completion?
25% remains = (1/2)² → 2 half-lives.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A zero-order reaction has a rate constant of 3.0 × 10⁻³ mol L⁻¹ s⁻¹. If the initial concentration is 0.09 mol L⁻¹, how l
t = (0.09 − 0.03)/(3.0×10⁻³) = 20 s.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A first-order reaction is 30% complete in 15 minutes. What is the rate constant?
k = (2.303/15) log(1/0.7) ≈ 0.0238 min⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
For the reaction A + 2B → C + D, the rate of formation of D is 0.04 mol L⁻¹ s⁻¹. What is the rate of disappearance of B?
−Δ[B]/Δt = 2 × 0.04 = 0.08 mol L⁻¹ s⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A first-order gaseous reaction has an initial pressure of 0.8 atm. After 30 s, the total pressure is 1.0 atm. What is th
x = 0.2, pA = 0.6. k ≈ 0.0096 s⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A zero-order reaction takes 120 s to reduce the concentration from 0.06 mol L⁻¹ to 0.03 mol L⁻¹. What is the rate consta
k = 0.03/120 = 2.5 × 10⁻⁴ mol L⁻¹ s⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions
A reaction has a rate constant of 0.08 s⁻¹. What is its order?
Unit s⁻¹ → first-order.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Pseudo First Order and Complex Reactions