Chemical Kinetics

As. temperature coefficient is 2, the rate of reaction becomes double when temperature is raised by 10 degrees. Hence when temperature is increased from 25� to 55� the rate increases in steps of 10�. i.e., 3 times. Hence, rate of reaction should increase times i.e, 8 times. Velocity at 55�C = 5 \times 8 = 40 times

From the two eqns. (i) and (ii),
t = 16 minutes.

The value of the rate constant or velocity constant does not depend upon the concentrations of the reactants.

Answer (b) Acid hydrolysis of sucrose

For every 10� rise in temperature, the rate of a chemical reaction doubles thus, for 60� rise in temperature the rate of reaction increases by = 64 times.

The rate constant of a reaction is related to temperature and activation energy by the Arrhenius equation: Where: - is the pre-exponential factor,
- is the activation energy,
- is the universal gas constant,
- is the temperature. From this equation, we can deduce that for the rate constant to be at its least value, the temperature should be low and the activation energy should be high. Therefore, the correct answer is Low T and high , as these conditions result in the lowest rate constant.

For a first-order reaction, the half-life is related to the rate constant by the formula: Given that the half-life , we can solve for : Thus, the rate constant is . Therefore, the correct answer is option (B).

For a first-order reaction, the integrated rate law is: where: - is the initial pressure, - is the final pressure, - is the rate constant, - is time. Substitute the given values: Solving for , we get 588 atm. Thus, the correct answer is Option (C).

Activation energy is the minimum energy required for a reaction to occur. The rate of reaction is inversely proportional to the activation energy. - Option (A) is true because higher activation energy does indeed slow down the reaction rate.
- Option (B) is true since catalysts lower the activation energy required for a reaction to proceed.
- Option (C) is incorrect. The SI unit for activation energy is J/mol, not J/mol/K.
- Option (D) is true because activation energy is a property of the reaction itself, not directly related to the rate. Thus, the incorrect statement is option C.

Since the reaction is a first-order reaction, the integrated rate law for first-order reactions is given by: Where: - is the initial pressure = 100 atm - is the pressure at time - is the rate constant = - is the time = 20 minutes = 1200 seconds Substituting the values: Thus, the final pressure is 96 atm.

Let's examine each match: % Option (A) A: For complex reactions order is determined by matches with R: Slowest rate determining step. % Option (B) B: For zero order reaction unit of k is same as that of matches with S: Rate law. % Option (C) C: Mathematical expression which gives relationship matches with D: For a first order reaction plot of log vs time gives. % Option (D) D: For a first order reaction plot of log vs time gives matches with Q: Slope = k/2.303. Thus, the correct match is:

Acidity in alcohols is influenced by the electron-withdrawing effects of the substituents on the carbon bearing the hydroxyl group. The more electron-withdrawing the substituents, the more they stabilize the negative charge on the oxygen atom after deprotonation, making the compound more acidi(C) 1. CH CH OH (Ethyl alcohol) has no electron-withdrawing group, so it is the least acidic among the given options. 2. CCl CH OH (Trichloroethanol) has three chlorine atoms attached to the carbon. Chlorine is a highly electronegative element, and its electron-withdrawing inductive effect increases the acidity by stabilizing the negative charge on the oxygen after deprotonation. 3. CF CH OH (Trifluoroethanol) has a trifluoromethyl group (-CF ) attached to the carbon. The trifluoromethyl group is an even stronger electron-withdrawing group than the chloro group, and it stabilizes the negative charge on oxygen more effectively, making trifluoroethanol the most acidi(C) Therefore, the correct order of increasing acidic strength is: Thus, the correct answer is (A)

The rate law for the reaction is given by: Where is the rate constant, is the order with respect to , and is the order with respect to . Now, the initial rate of the reaction is: Next, the concentrations of and are changed as follows: - The concentration of is tripled, so the new concentration is . - The concentration of is reduced to one third, so the new concentration is . The new rate will be: Thus, the ratio of the new rate to the initial rate is: Therefore, the ratio between the new rate and the original rate is . Thus, the correct answer is .

The ratio of the rate constants for the catalysed and uncatalysed reactions can be determined using the Arrhenius equation: Where: - and are the rate constants for the catalysed and uncatalysed reactions, respectively. - is the activation energy difference (100 J/mol here). - is the universal gas constant (8.314 J/mol·K). - and are the temperatures in Kelvin for the uncatalysed and catalysed reactions, respectively. Since the temperature change is negligible, we can approximate the ratio of rate constants as: Substituting the values: - J/mol, - J/mol·K, - K,
Thus, the ratio of the rate constants for the catalysed to uncatalysed reactions is approximately 1.0
4.

For the given data, we can use the rate law to determine the order of reaction: The rate law is: Where: - is the rate of decomposition of XY, - is the concentration of XY, - is the order of the reaction, - is the rate constant. Taking the ratios of the rates for two different concentrations, we can find the order : Using the first two points: Simplifying the equation:
Thus, the order of reaction is 2.