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Showing posts with label CHEMICAL KINETICS. Show all posts
Showing posts with label CHEMICAL KINETICS. Show all posts

Sunday, May 26, 2024

Derivation of Van't Hoff equation.

This equation gives the quantitative temperature dependance of equilibrium constant K. 

The relation between standard free energy change ∆G° and equilibrium constant is 
∆G° = – RT ln K ……(1) 
We know that, 
∆G° = ∆H° – T∆S° -(2)  

Substituting (1) in equation (2)  

– RT ln K = ∆H° – T∆S° 

Rearranging, 

ln K = − Δ H °/R T + T ΔS °/R T
ln K = − Δ 𝐻 °/ 𝑅 𝑇 + Δ 𝑆 °/ 𝑅   ….(3) 

Differentiating equation (3) with respect to temperature  
d(in K) = d(in K) / dT = ∆H° / RT2

Equation (4) is known as differential form of van't Hoff equation. 

On integrating the equation (4), between T1 and T2 with the respective equilibrium constants and K2 


Equation is known as integrated form of van't Hoff equation.

Tuesday, November 23, 2021

Class Claperon equation:


Vapour pressure is directly proportional to the Temperature so that on increasing temperature the rate of evaporation increases and rate of condensation decreases and hence vapour pressure increases.
The dependence of vapour pressure and temperature is given by CLASIUS CLAPERON equation.

Related topics:

What is relation between equilibrium constant and activation energy ?

Monday, May 10, 2021

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4x 10^13 sec^-1 and 98.6 kJ mole^-1 respectively. At what temperature, the reaction will have specific rate constant 1.1x 10^-3 sec^-1.

 Arrhenius equation:

The temperature dependence of rate of a chemical reaction can be accurately explained by Arrhenius equation. It was first proposed by Dutch chemist   J.H. Vant’s Hoff but Swedish chemist Arrhenius provides its physical justification and interpretation.

                            

Where  

 K= Rate constant

 A= Arrhenius constant or frequency factor or pre exponential factor

 R= Universal gas constant =25/3 joule per mole per second

Ea= Activation Energy

 T= temperature

-Ea/RT= Boltzmann factor or fraction of molecule having equal or greater than Activation energy or fraction of molecule that have kinetic energy greater than activation energy.


Related Questions:

(1) What is Arrhenius equation ?

(2) what happen when activation energy of a chemical reaction becomes equal to RT?

(3) What is the activation energy and how to different from threshold energy ?

(4) In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

(5) The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

(6) A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

(7) A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion. 

(8) The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^1 mol^1).

 

Thursday, October 1, 2020

The energy of activation for a reaction is 100 kJ mol^-1. Presence of a catalyst lowers the energy of activation by 75%. What will be effect on rate of reaction at 20”C, other things being equal ?

 

Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion. 

The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^1 mol^1). 

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 x10^13 sec^1 and 98.6 kJ mol1 respectively. At what temperature, the reaction will have specific rate constant 1.1x10^-3 sec^-1 ? 

At 407 K the rate constant of a chemical reaction is 9.5 x10^-5s^-1 and at 420 K, the rate constant is 1.9 x10^-4s^-1. Calculate the frequency factor of the reaction.

 

At 407 K the rate constant of a chemical reaction is 9.5 x10^-5s^-1 and at 420 K, the rate constant is 1.9 x10^-4s^-1. Calculate the frequency factor of the reaction.

 


Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion. 

The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^1 mol^1). 

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 x10^13 sec^1 and 98.6 kJ mol1 respectively. At what temperature, the reaction will have specific rate constant 1.1x10^-3 sec^-1 ?

 

 

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 x10^13 sec^1 and 98.6 kJ mol1 respectively. At what temperature, the reaction will have specific rate constant 1.1x10^-3 sec^-1 ?

 

Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion. 

The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^1 mol^1).

 

The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^-1 mol^-1).


Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion.

 

A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion.

 

Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

 

 

A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

 

Related Questions:

What is Arrhenius equation ?

what happen when activation energy of a chemical reaction becomes equal to RT?

What is the activation energy and how to different from threshold energy ?

In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

 

 

 

 

 

Saturday, June 27, 2020

What is Arrhenius equation ?

The temperature dependence of rate of a chemical reaction can be accurately explained by Arrhenius equation. It was first proposed by Dutch chemist   J.H. Vant’s Hoff but Swedish chemist Arrhenius provides its physical justification and interpretation.

Where  

 K= Rate constant

 A= Arrhenius constant or frequency factor or pre exponential factor

 R= Universal gas constant =25/3 joule per mole per second

Ea= Activation Energy

 T= temperature

-Ea/RT= Boltzmann factor or fraction of molecule having equal or greater than Activation energy or fraction of molecule that have kinetic energy greater than activation energy.

Related Questions:

(1) What is Arrhenius equation ?

(2) what happen when activation energy of a chemical reaction becomes equal to RT?

(3) What is the activation energy and how to different from threshold energy ?

(4) In Arrhenius equation for a certain reaction, the value of A and Ea (activation energy) are 4 × 10^13 sec–1 and 98.6 kJ mol–1 respectively. At what temperature, the reaction will have specific rate constant 1.1 × 10^–3 sec–1?

(5) The energy of activation for a reaction is 100 kJ mol–1. Presence of a catalyst lowers the energy of activation by 75%.What will be effect on rate of reaction at 20ºC, other things being equal?

(6) A drug becomes ineffective after 30 % decomposition. The original concentration of a sample was 5mg/mL which becomes 4.2 mg/mL during 20 months. Assuming the decomposition of first order , calculate the expiry time of the drug in months. What is the half life of the product?

(7) A first order reaction is 20 % completed in 10 minutes. Calculate the time taken for the reaction to go to 80 % completion. 

(8) The rate of a reaction triple when temperature changes from 20”C to 50”C. Calculate energy of activation for the reaction (R = 8.314 JK^1 mol^1).

Tuesday, June 9, 2020

Consider the following reaction: A(g) + B(g) --> AB (g)The activation energy of backward reaction exceeds that of the forward reaction by 2RT (in J per mole). If the pre-exponential factor of forward reaction is 4 times of the reverse reaction. The absolute value of (G) Gibbs energy at STP (in j per mole) for the reaction at 300 K is (Given ln2= 0.7, RT= 2500 J per Mole at 300 K and G is the Gibbs energy) (JEE Advanced 2018)


SOLUTION:  
Given condition

What is the activation energy and how to different from threshold energy ?

Threshold Energy and Activation Energy:
Threshold energy(THE): For a reaction to take place the reacting molecules must colloid together, but only those collisions, in which colliding molecules possess certain minimum energy is called threshold energy (THE or ET) or the total minimum energy that reacting species must possess in order to undergo effective collision to form product molecules is called threshold energy.
Activation energy (Ea): It is extra energy which must be possessed by reactant molecules so that collision between reactant molecules is effective and leads to formation of product molecules.
ET =Threshold Energy, (THE)

HR = Enthalpy or Energy or Potential of reactants.
HP = Enthalpy or Energy or Potential of product,
(Ea)f =Activation energy for forward reaction.
(Ea)b =Activation energy for backward reaction.
Activated complex: It is formed between reacting molecules which is highly unstable and readily changes into product.