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A rate law shows how the rate of a chemical reaction depends on reactant concentration. For a reaction such as aA → products, the rate law generally has the form rate = k[A]ⁿ, where k is a proportionality constant called the rate constant and n is the order of the reaction with respect to A.
- Reaction mechanism and rate law (article) | Khan Academy
A reaction that occurs in two or more elementary steps is...
- Reaction mechanism and rate law (article) | Khan Academy
- What Is The Rate Law?
- Rate Constants
- Differential Rate Equations
- Integrated Rate Equations
- Solved Examples on The Rate Law
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The rate law (also known as the rate equation) for a chemical reaction is an expression that provides a relationship between the rate of the reaction and the concentrations of the reactants participating in it.
Rearranging the rate equation, the value of the rate constant ‘k’ is given by: k = Rate/[A]x[B]y Therefore, the units of k (assuming that concentration is represented in mol L-1 or M and time is represented in seconds) can be calculated via the following equation. k = (M s-1)*(M-n) = M(1-n) s-1 The units of the rate constants for zero, first, secon...
Differential rate laws are used to express the rate of a reaction in terms of change in the concentration of reactants (d[R]) over a small interval of time (dt). Therefore, the differential form of the rate expression provided in the previous subsection is given by: -d[R]/dt = k[A]x[B]y Differential rate equations can be used to calculate the insta...
Integrated rate equations express the concentration of the reactants in a chemical reaction as a function of time. Therefore, such rate equations can be employed to check how long it would take for a given percentage of the reactants to be consumed in a chemical reaction. It is important to note that reactions of different orders have different int...
Example 1
For the reaction given by 2NO + O2→ 2NO2, The rate equation is: Rate = k[NO]2[O2] Find the overall order of the reaction and the units of the rate constant. The overall order of the reaction = sum of exponents of reactants in the rate equation = 2+1 = 3 The reaction is a third-order reaction. Units of rate constant for ‘nth’ order reaction = M(1-n) s-1 Therefore, units of rate constant for the third-order reaction = M(1-3) s-1 = M-2 s-1 = L2 mol-2 s-1
Example 2
For the first-order reaction given by 2N2O5→ 4NO2 + O2 the initial concentration of N2O5 was 0.1M (at a constant temperature of 300K). After 10 minutes, the concentration of N2O5was found to be 0.01M. Find the rate constant of this reaction (at 300K). From the integral rate equation of first-order reactions: k = (2.303/t)log([R0]/[R]) Given, t = 10 mins = 600 s Initial concentration, [R0] = 0.1M Final concentration, [R] = 0.01M Therefore, rate constant, k = (2.303/600s)log(0.1M/0.01M) = 0.003...
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In chemistry, the rate equation (also known as the rate law or empirical differential rate equation) is an empirical differential mathematical expression for the reaction rate of a given reaction in terms of concentrations of chemical species and constant parameters (normally rate coefficients and partial orders of reaction) only. [1]
Rate laws (sometimes called differential rate laws) or rate equations are mathematical expressions that describe the relationship between the rate of a chemical reaction and the concentration of its reactants. As an example, consider the reaction described by the chemical equation
Aug 26, 2023 · Explain the form and function of a rate law. Use rate laws to calculate reaction rates. Use rate and concentration data to identify reaction orders and derive rate laws. As described in the previous module, the rate of a reaction is often affected by the concentrations of reactants.
Nov 13, 2022 · The relation between the rate of a reaction and the concentrations of reactants is expressed by its rate law. For example, the rate of the gas-phase decomposition of dinitrogen pentoxide \[2N_2O_5 → 4NO_2 + O_2\] has been found to be directly proportional to the concentration of \(N_2O_5\): \[\text{rate} = k [N_2O_5]\]
A reaction that occurs in two or more elementary steps is called a multistep or complex reaction. A reaction intermediate is a chemical species that is formed in one elementary step and consumed in a subsequent step. The slowest step in a reaction mechanism is known as the rate-determining step.
