**1.** The decomposition ammonia on a platinum surface follows zero order kinetics.

2NH_{3}(g) N_{2}(g)+3H_{2}(g) K= 2.5x10^{-4} mole/l/sec. Determine the rate of

**a)** disapperance of NH_{3}

**b)** rate of formation of N_{2}

**c)** rate of formation of H_{2}.

**2. **The decomposition ammonia on a platinum surface follows zero order kinetics.

Calculate the value of rate constant K and the half life of the reaction. Given

**Time (seconds) ** ** Pressure of NH**_{3}(g) in Pascal

0 4x10^{-2}

100 3.5 x10^{-2}

200 3.0 x 10^{-2}

300 2.5 x 10^{-2}

**3.** A first order reaction is 20% complete in 10 minutes. Determine the time taken for 80% completion of the reaction.

**4. ** 2A +B A_{2}B K= 2.5 x10^{-4 }M^{-2} sec^{-1} Find the rate when the initial concentrations of [A] = 0.1M [B] = 0.2 M. Also find the rate when 0.04 moles/litre of A has reacted.Rate=K[A][B]^{2}

**5.** For a certain chemical reaction variation in the concentration in [R ] versus time(s) plot is given below

**i)** what is the order of the reactions?

**ii) **what are the units of rate constant k?

**iii)** give the relationship between k and t1/2

**iv)** what does the slope of the above line indicate?

**v)** draw the plot [R ] 0 / [R] versus time(s)

**6.** Consider the reaction R → P. The change in the concentration of R with shown in the following plot.

** i)** Predict the order of the reaction.

**ii)** Write the expression for half life of this reaction.

**7.** 2NO_{2}+F_{2} _2NO_{2}F Write the rate of reaction in terms of

**(a)** rate of formation of NO_{2}F

**(b)** rate of disappearance of NO_{2}

**(c)** rate of disappearance of F_{2}

**8.** The decomposition of NH3 follows zero order. 2 NH_{3} N_{2}+3H_{2} Find the rate of production of N_{2} and H_{2}.K=2.5x10^{-4}MS^{-1} −1

**9.** 2A+B+C_ A_{2}B+C Rate=K(A)(B)_{2} K=2x10_{-6}M_{-2}S_{-1}Calculate the initial rate when

**(A)**=0.1M

**(B)**=0.2M

**(C)**=0.6M Find the rate when 0.04mole of (A) is consumed.

**10**. 2NO_{2}+F_{2} _2NO_{2}F

**Experiment ** **(NO**_{2})M ** (F**_{2}) M **Rate(M/S)**

1 0.2 0.05 0.006

2 0.4 0.05 0.012

3. 0.8 0.10 0.048

Find the order with respect to NO_{2} and F_{2}.Also find the overall order of the reaction. Deduce the mechanism of the reaction.

**11.** Show that(a) 2t½=t¾ (b)Half life of a reaction is 10seconds.Find t_{2/3}

**12. **Hydrolysis of methyl acetate in aqueous solution has been studied by titrating liberated acetic acid with NaOH

rate=K(CH_{3}COOCH_{3}) (H_{2}O)

t/min 0 30 60 90

c/M 0.8500 0.8004 0.7538 0.7096

Show that it follows pseudo first order reaction as the concentration of water remains constant (1L of water=1000g) What is the value of K?

**13. **The rates of a reaction starting with initial concentrations 2x10^{-3}−3M and1x10^{-3}M are 2.4x10^{-4}M/s

and0.6x10^{-4}M/s respectively. Find the order of the reaction and rate constant K.

A+5B+6C 3L+3M |

**Experiment** |
**(A)M ** |
** (B)M** |
**(C)M** |
** Rate M/minute** |

1. |
0.02 |
0.02 |
0.02 |
00208 |

2. |
0.01 |
0.02 |
0.02 |
0.00104 |

3. |
0.02 |
0.04 |
0.02 |
0.00416 |

4. |
0.02 |
0.02 |
0.04 |
0.00832 |

Determine the order with respect to each reactant. Find K .Calculate the initial rate when concentration of each reactant is 0.01M.Find the initial rate of change in concentrations of B and L

**14.** Rate of a reaction becomes 1.414 times when concentration of the reactant is doubled. Find the order of the reaction.

**15. (a)** show that for a first order reaction t½ is independent of the initial concentration of the reactant.

**(b) **show that for a zero order reaction t½ is directly proportional to initial concentration of the reactant and inversely proportional to rate constant.

**16.** Rate constant of a reaction is 2M ^{-1} S ^{-1} at 700K and 32 M ^{-1} S ^{-1} at 800K.Find Ea

**17.** Rate of a reaction becomes 4 times when temperature changes from 27 ^{0}C to 37 ^{0}C. Find Ea.

**18.** Rate constant of a reaction at 700K and 760K are 0.01 M ^{-1} S ^{-1}and 0.105 M ^{-1} S ^{-1} respectively. Find A and Ea .

**19. ** Show that for a first order reaction, time required for 99.9% reaction is 10 times the time needed for 50% completion of the reaction.

**20.** A piece of wood shows C_{14} activity which is 60% activity found today. Find the age of the sample.t½=5770years.

**21. **The following data were obtained during the first order decomposition of SO_{2}Cl_{2} at constant

volume . SO_{2}Cl_{2}(g) SO_{2}(g) +Cl_{2}(g)

**Experiment** ** Time(sec) ** **Total pressure(atm)**

1 0 0.5

2 100 0.6

Calculate the rate when total pressure is 0.65 atmospheres.

**22.** 2N_{2}O_{5}(g) 2 N_{2}O_{4}(g) +O_{2}(g) follows first order kinetics at constant volume.

**Experiment** ** Time(sec)** **Total pressure(atm)**

1 0 0.5

2 100 0.512

Find the value of rate constant K.

**23. ** The time required for 10% completion of a first order reaction at 298K is equal to that required for

25% completion at 308K. Find Ea. Calculate K at 318K.

**24. **2HI(g) H_{2}(g) +I2(g) Ea at 581K is 209.5KJ/mole. Determine the fraction of molecules

having energy equal to or greater than Ea.

**25.** Ea of a reaction is 75 KJ/mole in the absence of a catalyst and 50KJ/mole in the presence of a Catalyst at 300K. Determine the extent to which the rate of reaction is increased.

**26**. The rate constant for the first order decomposition of H_{2}O_{2} is given as logK = 14.34 – 1.25x 104 K/T. Calculate Ea for this reaction. At what temperature will its half life be 256 minutes?

**27.** The decomposition of hydrocarbon follows the equation K = (4.5x 1011 sec-1) e-28000K/T

Calculate Ea

**28.** 2NO(g) + O_{2}(g) 2NO_{2}(g) occurs in one step. What will happen to the rate when the Volume of the reaction vessel is reduced to 1/3 of the original volume?

**29. **A reaction is first order with respect to A and second order with respect to B. What will happen to the rate if concentration of A and B are doubled?

**30.** Rate of a reaction becomes 1.414 times when concentration of the reactant is doubled. Determine the order of the reaction.

**31.** Rate constant K of a reaction varies with the temperature according to the equation logK = constant- Ea/2.303RT where Ea is activation energy of the reaction. When a plot of logK vs 1/T , a straight line with a slope – 6670K is obtained. Find Ea. [R=8.314J/K/mole]

**32. ** The possible mechanism for the reaction

2 NO(g)+O_{2}(g) 2 NO_{2}(g) is

**i)** NO(g) +O_{2}(g) NO_{3}(g) [Fast]

** ii)** NO_{3}(g) +NO(g) NO_{2}(g)+NO_{2}(g) [slow]

Submitted By : Mr. R. Srinivas Vasudevamurthy

Email: vasudm@yahoo.co.uk