Why is that instantaneous rate of reaction does not change when a part of the reacting solution is taken out?
It DOES change
The instantaneous rate of reaction refers to the rate at a specific moment during a chemical reaction. It is determined by measuring the change in the concentration of a reactant or product with respect to time at that particular moment.
When a part of the reacting solution is taken out, the total volume of the solution decreases, but the total number of reactant particles remains the same. Therefore, the concentration of the reactants and products in the remaining solution increases, but the ratio between their concentrations remains unchanged.
The rate of reaction depends on the concentrations of the reactants. Since the concentration ratios remain the same, the rate of reaction, including the instantaneous rate, is not affected by removing a portion of the mixture. The remaining solution still contains the same proportions of reactants, which allows the reaction to continue at the same rate.
To determine the instantaneous rate of reaction, you can use the method of initial rates. This involves measuring the change in concentration of a reactant or product over a short period of time near the start of the reaction when the concentration changes most rapidly. By dividing the change in concentration by the corresponding time interval, you can calculate the instantaneous rate at that specific moment.