Advertisements
Advertisements
प्रश्न
Mention the factors that affect the rate of a chemical reaction.
Advertisements
उत्तर
The factors that affect the rate of a reaction are as follows:
(i) Nature of the reactant - The rate of reaction depends on the nature of the reactant. For instance, ionic molecules react more quickly than covalent ones.
(ii) State of reactants - Solid reactions are slower, liquid reactions are faster, and gas reactions are very quick.
(iii) Temperature - The rate of reaction is mainly affected by temperature. Every 10°C rise in temperature leads to an increased rate of reaction by 2-3 times.
`(r_(t + 10))/r_t` = 2 − 3
This ratio is called the temperature coefficient.
There are two reasons why the rate of reaction increases with increasing temperature.
- Increasing temperature raises the average kinetic energy of reactant molecules, increasing the rate of collisions.
- As temperature rises, the number of molecules with threshold energy increases, resulting in more active molecules. As a result, the number of effective collisions grows. As a result, the rate of reaction rises.
(iv) Concentration - The rate of reaction depends on the concentration of reactants.
Rate = k × Cn, where n = order of reaction, C = concentration of reactant.
(v) Catalyst - The presence of a catalyst changes the rate of the reaction. It lowers the activation energy by producing a chemical intermediate, lowering the potential energy barrier. Thus, the rate of reaction increases.
APPEARS IN
संबंधित प्रश्न
For a reaction A + B ⟶ P, the rate is given by
Rate = k [A] [B]2
How is the rate of reaction affected if the concentration of B is doubled?
The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :
SO2Cl2 (g) → SO2 (g) + Cl2 (g)
| Experiment | Time/s–1 | Total pressure/atm |
| 1 | 0 | 0.4 |
| 2 | 100 | 0.7 |
Calculate the rate constant.
(Given : log 4 = 0.6021, log 2 = 0.3010)
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{H2O2_{( aq)} + 3I^-_{( aq)} + 2H^+ -> 2H2O_{(l)} + I^-_3}\] Rate = k[H2O2][I−]
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{CH3CHO_{(g)} -> CH4_{(g)} + CO_{(g)}}\] Rate = k [CH3CHO]3/2
From the rate expression for the following reaction, determine the order of reaction and the dimension of the rate constant.
\[\ce{C2H5Cl_{(g)} -> C2H4_{(g)} + HCl_{(g)}}\] Rate = k [C2H5Cl]
Write the principle behind the following methods of refining:
Hydraulic washing
Define the following term:
Pseudo first-order reaction
The value of rate constant of a pseudo first order reaction ______.
For which type of reactions, order and molecularity have the same value?
Why does the rate of any reaction generally decreases during the course of the reaction?
Assertion: Order of the reaction can be zero or fractional.
Reason: We cannot determine order from balanced chemical equation.
Assertion: The enthalpy of reaction remains constant in the presence of a catalyst.
Reason: A catalyst participating in the reaction, forms different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.
The role of a catalyst is to change
The rate constant for the reaction \[\ce{2H2O5 -> 4NO2 + O2}\] is 30 × 10–5 sec–1. if the rate is 204 × 10–5 mol L–1 S–1, then the concentration of N2O5 (in mol–1) is-
The half-life period of a. substance in a certain enzyme catalysed reaction is 138 s. The time required for the concentration of the substance to fall from 1.28 mol–1 to 0.04 mg L–1 is
For the reaction, \[\ce{A +2B → AB2}\], the order w.r.t. reactant A is 2 and w.r.t. reactant B. What will be change in rate of reaction if the concentration of A is doubled and B is halved?
Read the following passage and answer the questions that follow:
|
The rate of reaction is concerned with decrease in the concentration of reactants or increase in the concentration of products per unit of time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law: Rate = k[A]x [B]y x and y indicate how sensitive the rate is to change in concentration of A and B. Sum of x + y gives the overall order of a reaction. |
- What is the effect of temperature on the rate constant of a reason? [1]
- For a reaction \[\ce{A + B → Product}\], the rate law is given by, Rate = k[A]2 [B]1/2. What is the order of the reaction? [1]
- How order and molecularity are different for complex reactions? [1]
- A first-order reaction has a rate constant 2 × 10–3 s–1. How long will 6 g of this reactant take to reduce to 2 g? [2]
OR
The half-life for radioactive decay of 14C is 6930 years. An archaeological artifact containing wood had only 75% of the 14C found in a living tree. Find the age of the sample.
[log 4 = 0.6021, log 3 = 0.4771, log 2 = 0.3010, log 10 = 1] [2]
The following data was obtained for chemical reaction given below at 975 K.
\[\ce{2NO(g) + 2H2(g) -> N2(g) + 2H2O(g)}\]
| [NO] | [H2] | Rate | |
| Mol L-1 | Mol L-1 | Mol L-1 s-1 | |
| (1) | 8 × 10-5 | 8 × 10-5 | 7 × 10-9 |
| (2) | 24 × 10-5 | 8 × 10-5 | 2.1 × 10-8 |
| (3) | 24 × 10-5 | 32 × 10-5 | 8.4 × 10-8 |
The order of the reaction with respect to NO is ______. (Integer answer)
Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.
Reason (R): For a complex reaction, molecularity has no meaning.
