Theory and Key Terms of Acid-Base Titration You Need to Know

There are hundreds of organic and inorganic compounds. Titration can be used to assess if a substance is acidic or basic. A base (alkali) is titrated with an acid, and an acid is titrated with a base. In titration, the endpoint is determined through the use of an indication. The term titration is derived from the Latin word titulus, which means “inscription” or “title” and the word title translates to “rank” in French. This means the term titration refers to the measurement of a solution’s concentration or rank in relation to water with a pH of 7. In acid-base titration there are two indicators, namely phenolphthalein and methyl-orange. The choice of indicators in acid-base titration helps in finding the result of the titration.

The Equivalent Point and the Endpoint in a Titration

The endpoint of a reaction is the moment at which the reaction is complete. The endpoint is determined by a physical change in the solution or the addition of an indicator reagent. The equivalent point is the point at which the amount of reagent supplied equals the amount of reacting material in the titrated solution. It is worth noting that the endpoint and equivalence point cannot be the same. The endpoint is usually only observed after a small amount of titrant is added in excess. If there is a discrepancy between the endpoint and the comparable point, the experiment has gone wrong.

Titration Curve

The graph is plotted during titration in which the pH of a solution is represented. The curve obtained during the process is called the titration curve. This curve helps us to know how the pH value of a solution changes when a measured amount of a known chemical is added to it. The titration curve at any point will give us information on the pH of the solution with respect to the increase in the volume of the known chemical.

Examples of Acid-Base Titration 

With titrations, it is critical to measure the quantities precisely, and the burette is the tool of choice. It is a liquid dispensing device that can accurately show the amount of a liquid. Let us look at the following example:

Assume that 25.66 ml or 0.02566 L of 0.1078 M HCl was used to titrate an unknown quantity of NaOH,. What was the sample’s NaOH concentration? 

The number of moles of HCl reacting is calculated as follows: 

(0.10266) 0.01078 M mol HCl = 0.002766 mol HCl, 

There is also a balanced chemical equation interaction:

NaCl+H2O → HCl+NaOH

Now we can figure out how many moles of NaOH reacted.

Using the molar mass of NaOH (40.00 g/mol), we can convert this quantity to mass: 40.

Important Terms of Acid-Base Titration

• Titration occurs when an unknown strength solution is added to a defined volume of a treated sample containing an indicator. 
• A titrant is a solution with a known concentration strength that is used in the titration.
• Any solution to which the titrant contributes and which includes the ion to be detected is referred to as a titrant.
• When a reagent is added to totally react with a material, the equivalent point is reached. 

The Efficiency of the Titration Model

The model is constructed using the dissociation constant rules and the amount of moles present. Its purpose is to keep the percent error as low as possible (1 percent), which it achieves. 

When the titration model’s findings are compared to the theoretical findings, the percent efficiency is remarkable (99.4%). The titration model, on the other hand, is incapable of reducing experimental errors, which implies that it is incapable of correcting any faults made during the experiment. The percent error in this experiment is 9%, indicating that the computation or determination of the equivalence point is relatively imprecise. To reduce the percentage error in the dissociation constant, a computer algebra system is required, and the acid-base titration should be performed numerous times to decrease experimental mistakes. 

Furthermore, the titration model is 99.4% efficient, indicating that any result achieved would be accurate. The titration model also demonstrates a relationship between pH, pKa, volumes, and concentrations. This relationship may be used to determine any of the four criteria. As a result, this mathematical model also describes the many characteristics (pH, pKa, volume, concentration) of the chemicals used (acid or base). Finally, the acid concentration is calculated using this model.

Other chemical parameters (pH, pKa, volume, etc.) might be monitored as well. The dissociation constant will be unknown if the concentration values of two acidic compounds are mislabeled. The two compounds can be easily distinguished using the titration model created in this work, and the confusion between them can be resolved.

Conclusion

In this article, we learned about the important terms of acid-base titration, the titration curve and equivalence point, and how these are helpful in bringing out accurate results. We also learned about the efficiency of the titration model, the endpoint and equivalence point, and how the graph of a titration curve helps us know the nature of the solution at any instance. There could be experimental errors, and the theory and experimental value are close enough to rely on the experimental value. We have understood why the experiment needs to be conducted multiple times and that the average data needs to be tabulated as well.