Advertisements
Advertisements
प्रश्न
With the help of an example explain what is meant by pseudo first order reaction.
Advertisements
उत्तर
Pseudo first order reaction: Reaction which appears to be a second order reaction, but actually is first order reaction is called pseudo first order reaction. This condition occurs in a chemical reaction between two substances when one reactant is present in large amount. The concentration of reactant present in excess does not gat alterned much during the course of the reaction. Due to this reaction behaves as first order reaction.
E.g. hydrolysis of esters
\[\ce{CH3COOC2H5 + H2O -> CH3COOH + C2H5OH}\]
Rate law for this reaction is; rate = \[\ce{k[CH3COOC2H5]][H2O]}\]
But the concentration of water does not change during the course of the reaction. So; \[\ce{H2O}\] is constant.
Therefore rate = \[\ce{k1[CH3COOC2H5]}\], where \[\ce{k = k[H2O]}\].
The reaction behaves as a first order reaction.
APPEARS IN
संबंधित प्रश्न
A first order reaction has a rate constant 1.15 × 10−3 s−1. How long will 5 g of this reactant take to reduce to 3 g?
Time required to decompose SO2Cl2 to half of its initial amount is 60 minutes. If the decomposition is a first order reaction, calculate the rate constant of the reaction.
The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume.
\[\ce{SO2Cl2_{(g)} -> SO2_{(g)} + Cl2_{(g)}}\]
| Experiment | Time/s–1 | Total pressure/atm |
| 1 | 0 | 0.5 |
| 2 | 100 | 0.6 |
Calculate the rate of the reaction when total pressure is 0.65 atm.
In a pseudo first order reaction in water, the following results were obtained:
| t/s | 0 | 30 | 60 | 90 |
| [A]/mol L−1 | 0.55 | 0.31 | 0.17 | 0.085 |
Calculate the average rate of reaction between the time interval 30 to 60 seconds.
For the decomposition of azoisopropane to hexane and nitrogen at 543 K, the following data are obtained.
| t (sec) | P(mm of Hg) |
| 0 | 35.0 |
| 360 | 54.0 |
| 720 | 63.0 |
Calculate the rate constant.
The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 308 K. If the value of A is 4 × 1010 s−1. Calculate k at 318 K and Ea.
A first order reaction is 50% complete in 25 minutes. Calculate the time for 80% completion of the reaction.
In the presence of acid, the initial concentration of cane sugar was reduced from 0.2 M to 0.1 Min 5 hours and to 0.05 Min 10 hours. The reaction must be of?
The reaction X → product
Follow first order of kinetics. In 40 minutes the concentration of 'X' changes from 0.1 m to 0.025. M. The rate of reaction when concentration of X is 0.01 m is.
Time required to decompose SO2Cl2 to half of its initial concentration is 60 minutes. If the de-composite is a first order reaction, calculated the rate constant of the reaction-
In a first order reaction the concentration of reactants decreases from 400mol L-1 to 25 mol L-1 in 200 seconds. The rate constant for the reaction is ______.
Observe the graph shown in figure and answer the following questions:
- What is the order of the reaction?
- What is the slope of the curve?
- Write the relationship between k and t1/2 (half life period).
The decomposition of formic acid on gold surface follows first-order kinetics. If the rate constant at 300 K is 1.0 × 10−3 s−1 and the activation energy Ea = 11.488 kJ mol−1, the rate constant at 200 K is ______ × 10−5 s−1. (Round off to the Nearest Integer)
(Given R = 8.314 J mol−1 K−1)
Define first-order reaction.
Write the equation for integrated rate law for a first order reaction.
Write the unit of rate constant [k] for the first order reaction.
