Welcome to Chem Zipper.com......: CHEMICAL KINETICS

## Search This Blog

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, September 5, 2023

### A certain Zero order reaction has rate constant K is 0.025 MS^-1 for disappearance of A . What will be the concentration of A after 15 sec if initial concentration is A is 0.5M.

(A) 2.5 M  (B) 0.5 M (C) 1.5 M  (D) 0.125 M

### The rate constant for zero order reaction is 2× 10^-2 Mole L^-1 sec-1. If the concentration of reactant after 25 sec is 0.5M ,the initial concentration must have been ?

(A) 1M (B) 2M (C) 1.5M  (D) 2.5M

### Consider a general reaction A--->B follow zero order kinetics.if concentration of A is reduces from 0.1 M to 0.05 M in 10 second then calculate time taken when concentration reduce to 0.025 M.

(A) 2.5 sec  (B) 2 sec (C) 5 sec   (D) 10 sec

## 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:

## 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:

## 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:

### 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:

### 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:

### 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:

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

Related Questions:

### 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:

## Monday, September 21, 2020

### Chemical Kinetics

(1) Physical Chemistry
Book by O.P Tandon

(2) Physical chemistry
Book by KS Verma (Cengage Publications)

(3) Physical Chemistry
Book by P.W. Atkins (Oxford publication)

(4) Physical Chemistry

(5) Physical Chemistry
Book by Ranjeet Shahi (Arihant publication)

(6) Balaji Advanced problems in Physical chemistry
Book by Narendra Awasthi

(7) Modern Approach to Chemical Calculations
Book by R.C. Mukherjee

## 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:

## Tuesday, June 9, 2020

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.