Basic knowledge of titration analysis

Titration analysis method refers to the method of making a sample into a solution, adding a standard solution of known concentration until the end, and calculating the content of the component to be tested according to the volume of the standard solution used

2.

1 Overview

The titration analysis method is to add a standard titration solution (titrant) dropwise to the solution of the tested substance until the reaction between the substances reaches the stoichiometric point, and calculate the content of the tested component according to the concentration of the standard solution used and the volume consumed Method

The key to titration is whether it can accurately indicate the arrival of the chemical reaction metering point

We call the above-mentioned operation of dropping a standard solution of known and accurate concentration with a burette as titration; the equivalent point when the chemical reaction equilibrium between substances is reached is called the stoichiometric point; the turning point when the indicator color changes is called the titration end point; the titration end point The stoichiometric point may be the same or inconsistent.

(1) The reaction is completed quantitatively, that is, the reaction proceeds according to a certain reaction formula, no side reaction occurs, and the reaction proceeds to completion, which is the basis of quantitative calculation

(2) The reaction can be completed quickly.

(3) There is an appropriate method to determine the titration end point

Titration analysis method is an important type of analysis method in chemical analysis.

Titration analysis is a very widely used method in quantitative analysis

2.

In the direct titration method, the reaction formula of test substance A and titrant B is as follows:

When the titration reaches the stoichiometric point, a mol A happens to interact completely with b mol B, that is

For example, C ₂ O ₄ ^2- and MnO ₄ ^- react with each other in a molar ratio of 5:2:

5C ₂ O _.

Therefore

If the substance to be tested is a solution, its volume is V _A , and its concentration is C _A.

In practical applications, for the convenience of calculation, the amount of substance (n) in the equivalent unit is often used to represent the amount of substances participating in the reaction substances A and B.

Can be simplified to

n _A = n _B

and

Can be simplified to

C _A V _A =C _B V _B

This simplifies the calculations in redox titration and indirect titration
.
For example, when both oxalic acid and potassium permanganate are equivalent substances, they can be written as

Similarly, if the concentrations of oxalic acid and potassium permanganate standard solutions are C(½H ₂ C ₂ O ₄ )=0.
1000mol/L and C(⅕KMnO ₄ )=0.
1000mol/L, then there is an equal volume between them In the solution, the amount of solute contained in the equivalent unit is also equal
.

What is introduced here is only the calculation of the quantitative relationship of the titration analysis method, and the detailed calculation will be discussed in various analysis methods
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