Question: Define the rate-determining step....

Question

Define the rate-determining step.

Answer 1

Solution

Chemistry exists around the chemical reaction. Some reactions are slow, and some are very fast, it all depends on how much the element is reactive.During the reaction, many products are produced. And it happens in many steps.

Complete answer:
Rate Determining step-When the slowest step determined during the whole chemical reaction is known as the rate-determining step. Due to it, we can identify the speed of the chemical reaction.
Example - $$$$ $N{O_2} + CO \to NO + C{O_2}$
The above reaction occurred in a single step, so its reaction rate is proportional to the rate of collision.
Many reactions occur in more than one step.
$2N{O_2} + {F_2} \to 2N{O_2}F$

It occurs in elementary steps
1. $N{O_2} + {F_2} \to N{O_2}F + F$
2. $N{O_2} + F \to N{O_2}F$

Another example is Nucleophilic substitution
1. Carbonate formation $R - Br \to {R^ + } + B{r^ - }$
2. Hydroxide attack on Nucleophilic ${R^ + } + O{H^ - } \to ROH$

Here $R$ is $t - {C_4}{H_9}$
The first step is the rate-determining step also known as unimolecular.
And the second step is much faster and not dependent on $O{H^ - }$ .
As we know that so many factors affect the rate of reaction.
1. Physical state: Physical state of the reactant plays an important role in the chemical reaction. If reactants are in the same phase, they will be in contact due to thermal reaction. If the reactant is in a separate phase, they will contact a limited manner.
2. Nature of reactant: The rate of reaction depends on the nature of the reactant. Acid/base, ion exchange, and formation of salt reactions are usually fast.
3. Surface area: Frequency of collision between reactants increases as increases surface area.
4. Concentration: It enhances the rate of reaction, reactant reacts actively with others.

Note: Equilibrium- When the rate of forwarding and reverse reaction will be the same and no further change required in reactant and product. Some more factors also affect the chemical reaction like temperature, catalyst, pressure, and Absorption of light.