Q. No.The thermal decomposition of a compound is of first order. If 50 % of a sample of the compound decomposes in 120 minutes, how long will it take for 90 % of the compound to decompose?
1. 399 min
2. 410 min
3. 250 min
4. 120 min
The first order rate constant for a certain reaction increases from\(1.667 \times 10^{-6} \mathrm{~s}^{-1} \text { at } 727^{\circ} \mathrm{C} \text { to } 1.667 \times 10^{-4} \mathrm{~s}^{-1} \text { at } 1571{ }^{\circ} \mathrm{C}.\) The rate constant at \(1150^{\circ} \mathrm{C}\) is:
(assume activation energy is constant over the given temperature range)
| 1. | \(3.911 \times 10^{-5} \mathrm{~s}^{-1} \) | 2. | \(1 .139 \times 10^{-5} \mathrm{~s}^{-1} \) |
| 3. | \(3.318 \times 10^{-5} s^{-1} \) | 4. | \(1.193 \times 10^{-5} \mathrm{~s}^{-1}\) |
The rate constant of a particular reaction has the dimension of frequency. The order of the reaction is:
1. Zero.
2. First.
3. Second.
4. Fractional.
The half life period of gaseous substance undergoing thermal decomposition was measured for various initial pressure ‘P’ with the following result.
P(mm) 250 300 400 450
(min) 136 112.5 85 75.5
Calculate the order of reaction.
(A) 2
(B) 4
(C) 6
(D) 10
The decomposition of A into product has value of k as \(4.5 \times 10^3 \mathrm{~s}^{-1} \text { at } 10^{\circ} \mathrm{C}.\) Energy of activation of the reaction is \(60 \mathrm{~kJ}~mol^{-1}.\) The temperature at which value k would become \(1.5\times10^4~s^{-1}\) is :
| 1. | \(12{ }^{\circ} \mathrm{C} \) | 2. | \(24^{\circ} \mathrm{C} \) |
| 3. | \(48^{\circ} \mathrm{C} \) | 4. | \(36^{\circ} \mathrm{C}\) |
The rate constant for a first order reaction is . How much time will it take to reduce the initial concentration of the reactant to its 1/16th value –
(A) 0.046 s
(B) 0.46 s
(C) 1.124 s
(D) 2.123 s
The rate of reaction triples when the temperature changes from \(20{ }^{\circ} \mathrm{C} \text { to } 50^{\circ} \mathrm{C}\). The energy of activation for the reaction will be:
| 1. | \(28.81 \mathrm{~kJ} \mathrm{~mol}^{-1} \) | 2. | \(38.51 \mathrm{~kJ} \mathrm{~mol}^{-1} \) |
| 3. | \(18.81 \mathrm{~kJ} \mathrm{~mol}^{-1} \) | 4. | \(8.31 \mathrm{~kJ} \mathrm{~mol}^{-1}\) |
A catalyst lowers the activation energy of a reaction from 20 kJ mol–1 to 10 kJ mol-1. The temperature at which the uncatalysed reaction will have the same rate as that of the catalysed at 27 oC will be:
1. \(-123\ ^{\circ}C\)
2. \(-327\ ^{\circ}C\)
3. \(327\ ^{\circ}C\)
4. \(23\ ^{\circ}C\)
The rate constant, the activation energy, and the Arrhenius parameter of a chemical reaction at 25°C are 3.0×10-4 s-1, 104.4 kJ mol-1 and 6.0×1014s-1 respectively.
The value of the rate constant as T → ∞
will be:
1. 2.0 × 1018 s-1
2. 6.0 × 1014 s-1
3.
4. 3.6 × 1030 s-1
The kinetic data for the reaction: 2A + B2 → 2AB are as given below
| [A]/mol L-1 | [B2]/mol L-1 | Rate/mol L-1s-1 |
| 0.5 | 1.0 | 2.5 × 10-3 |
| 1.0 | 1.0 | 5.0 × 10-3 |
| 0.5 | 2.0 | 1 × 10-2 |
The order of reaction with respect to A and B2 is, respectively:
| 1. | 1 and 2 | 2. | 2 and 1 |
| 3. | 1 and 1 | 4. | 2 and 2 |
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