Initial Concentration

The concentration of the solution tells you how much solute has been dissolved in the solvent. Dilution is the addition of solvent, which decreases the concentration of the solute in the solution. The first measured concentration of a compound in a substance is the initial concentration. When both the reactants and the product are in a concentration that doesn't modify according to the time, it's stated to be in a state of equilibrium. During this state, the speed of forward reaction is the same as the rate of backward reaction. For a reaction, if you recognise the initial concentrations of the substances, you'll be able to calculate the equilibrium concentration. We will be focusing on how to calculate the initial concentration of a substance.

What is Concentration?

In Chemistry, concentration refers to the quantity of a substance in an outlined space. In chemistry, the concentration of a solution is the amount of a solute that is contained in a specific amount of solvent or solution. Knowing the concentration of solutes is vital in controlling the ratio of reactants for solution reactions.

Initial Concentration Formula

The formula below is employed in laboratories to calculate the final concentrations, volume which is unknown or the initial concentration of a solution.

${{C}_{1}}{{V}_{1}}={{C}_{2}}{{V}_{2}}$

${{C}_{1}}=\frac{{{C}_{2}}{{V}_{2}}}{{{V}_{1}}}$

Where, C1 = Initial concentration of solution

V1 = Initial volume of solution

C2 = Final concentration of solution

V2 = Final volume of solution

How to Find Initial Concentration?

We can also use integrated rate laws, and rate constants to find out how to calculate the initial concentrations or final concentrations.

The common integrated rate laws:

For a zero order reaction:

rate = k

The integrated rate law is:

$[A]$ = -kt + [A_o]

[Ao] = $[A]$ + kt

For first order reaction:

rate = k$[A]$

The integrated rate law is:

ln $[A]$ = -kt + ln [Ao]

ln [Ao] = ln $[A]$ + kt

Here, $[A]$ = final concentration or concentration of product.

[Ao] = Initial concentration or concentration of reactant.

k= is the rate constant and t is time taken for reaction to complete.

What is the Initial Concentration of HCl?

A sample problem is discussed below to find the concentration of HCl solution.

Q. If 100 ml of 0.5 M HCl solution is diluted with water to 1000 ml, find the new concentration or final concentration of the solution.

Ans. By using the solution dilution equation , ${{C}_{1}}{{V}_{1}}={{C}_{2}}{{V}_{2}}$

The initial concentration of HCl , C1 = 0,5 M

Initial volume ,V1=100 ml

Final concentration of HCl , C2 = to find

Final volume , V2 = 1000 ml.

${{C}_{2}}=\frac{{{C}_{1}}{{V}_{1}}}{{{V}_{2}}} \\$

${{C}_{2}}=\frac{0.5\times 100}{1000}=0.05M \\$

Therefore, the final concentration is 0.05 M.

Interesting Fact

• To concentrate a solution, one should add more solute, or reduce the quantity of solvent.

• The concentration of a solute is incredibly necessary in learning chemical reactions because it determines how usually molecules collide in solution and therefore indirectly determines the rates of reactions and also the conditions at equilibrium.

Conclusion

A dilution may be used to not only lower the concentration of the analyte being tested but also additionally to help minimise interferences from different compounds within the sample that would unnaturally change the analysis. In this article, the determination of initial concentration by using dilute equation or integrated rate law equation is explained with the assistance of a solved example.