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
Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law with t1/2 = 3 hours. What fraction of the sample of sucrose remains after 8 hours?
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.
A first order reaction is 50% complete in 25 minutes. Calculate the time for 80% completion of the reaction.
Show that the time required for 99.9% completion of a first-order reaction is three times the time required for 90% completion.
Straight line graph for first order reaction is obtained between ____________.
State a condition under which a bimolecular reaction is kinetically first order reaction.
The rate constant of a first order reaction is 6.9 × 10–3s–1. How much time will it take to reduce the initial concentration to its 1/8th value?
In the first order reaction, half of the reaction is complete in 100 seconds. The time for 99% of the reaction to occurs will be
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).
Gaseous cyclobutene isomerizes to butadiene in a first order process which has a 'k' value of 3.3 × 10−4 s−1 at 153°C. The time in minutes it takes for the isomerization to proceed 40% to completion at this temperature is ______. (Rounded-off to the nearest integer)
A definite volume of H2O2 undergoing spontaneous decomposition required 22.8 c.c. of standard permanganate solution for titration. After 10 and 20 minutes respectively the volumes of permanganate required were 13.8 and 8.25 c.c. The time required for the decomposition to be half completed is ______ min.
The slope in the plot of `log ["R"]_0/(["R"])` Vs. time for a first-order reaction is ______.
Radioactive decay follows first-order kinetics. The initial amount of two radioactive elements X and Y is 1 gm each. What will be the ratio of X and Y after two days if their half-lives are 12 hours and 16 hours respectively?
How will you represent first order reactions graphically?
Define first-order reaction.
Write the unit of rate constant [k] for the first order reaction.
