Advertisements
Advertisements
प्रश्न
A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75% of the reaction will be completed.
(Given : log = 2 = 0·3010, log 3 = 0·4771, log 4 = 0·6021)
Advertisements
उत्तर
For a first order reaction
`t = 2.303/k log [R]_0/[R]`
`k = 2.303/"20 min" log 100/(100 - 25)`
`= 2.303/"20 min" log 4/3`
`= 2.303/"20 min" (log 4 - log 3)`
`= 2.303/"20 min" (0.6021 - 0.4771)`
= 1.44 x 10-2 min-1
The time when 75% of the reaction completed can be calculated as
`t = 2.303/k log 100/(100 - 75)`
`= 2.303/(1.44 xx 10^(-2)) log 4`
`= 2.303/(1.44 xx 10^(-2)) (0.6021)`
= 96.3 min (approximately)
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?
In a pseudo first order hydrolysis of ester 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.
The rate constant for a first order reaction is 60 s−1. How much time will it take to reduce the initial concentration of the reactant to its `1/16`th value?
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.
Following data are obtained for reaction :
N2O5 → 2NO2 + 1/2O2
| t/s | 0 | 300 | 600 |
| [N2O5]/mol L–1 | 1.6 × 10-2 | 0.8 × 10–2 | 0.4 × 10–2 |
1) Show that it follows first order reaction.
2) Calculate the half-life.
(Given log 2 = 0.3010, log 4 = 0.6021)
Define order of reaction. How does order of a reaction differ from molecularity for a complex reaction?
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?
What is the rate constant?
Write the equation for integrated rate law for a first order reaction.
Show that `t_(1/2)= 0.693/k` for first reaction.
