The molecularity of the elementary step Cl₂ + H₂ → 2HCl is:
Two molecules collide → molecularity = 2.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
Chemical Kinetics
Practice questions focused on chemical kinetics, including reaction rates and the factors that influence them.
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The rate constant of a reaction is 3.0 × 10⁻³ s⁻¹ at 27°C. If the activation energy is 55 kJ/mol, what is the rate const
k₂ ≈ 6.12 × 10⁻³ s⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction’s rate increases by 2.25 times when the temperature rises from 300 K to 310 K. What is the activation energy
log 2.25 ≈ 0.352 → Ea ≈ 62.7 kJ mol⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
For a first-order reaction, the time for 99% completion is approximately how many times the half-life?
t₉₉ / t½ ≈ 6.64 ≈ 7.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
The rate law for a reaction is Rate = k[A]²[B]. What is the overall order of the reaction?
Overall order = 2 + 1 = 3.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction has the rate law Rate = k[A]². If the concentration of A is tripled, by how many times will the rate increase
New rate = 9 × initial rate.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
The decomposition of a gas follows first-order kinetics with an initial pressure of 2.0 atm. After 60 s, the total press
x = 0.8, pA = 1.2. k ≈ 0.00675 s⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction’s rate increases by 3 times when the temperature rises from 290 K to 300 K. What is the activation energy (R
log 3 → Ea ≈ 79.4 kJ mol⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction’s rate increases by 2.83 times when the temperature rises from 300 K to 310 K. What is the activation energy
log 2.83 ≈ 0.451 → Ea ≈ 80.3 kJ mol⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction’s rate increases by 2 times when the temperature rises from 25°C to 35°C. What is the activation energy (R =
log 2 → Ea ≈ 52.8 kJ mol⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
A reaction’s rate constant increases from 2.5 × 10⁻⁴ s⁻¹ at 27°C to 7.5 × 10⁻⁴ s⁻¹ at 37°C. What is the activation energ
log 3 → Ea ≈ 84.9 kJ mol⁻¹.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy
The molecularity of the elementary step H₂ + 2ICl → 2HCl + I₂ is:
Three molecules collide → molecularity = 3.
Ref: NCERT Class 12 Chemistry > Chapter 3: Chemical Kinetics > Topic: Temperature Dependence - Arrhenius Equation and Activation Energy