Neutralization reactions titration

FIGURE 11.7 A typical pH curve for the titration of a weak base with a strong acid. The stoichiometric point (S) occurs at pH < 7 because the salt formed by the neutralization reaction has an acidic cation. 

The pH at the stoichiometric point depends on the type of salt produced in the neutralization reaction. At the stoichiometric point of the titration of formic acid, HCOOH, with sodium hydroxide,... 

Well after the stoichiometric point in the titration of a weak acid with a strong base, the pH depends only on the concentration of excess strong base. For example, suppose we went on to add several liters of strong base from a giant buret. The presence of salt produced by the neutralization reaction would be negligible relative to the concentration of excess base. The pH would be that of the nearly pure titrant (the original base solution). 

We are asked for the molarity of an acid. The analysis is a titration. Knowing that the wastewater contains strong acid, we can write the general acid-base neutralization reaction ... 

In a titration, one solution is added slowly to the other until the equivalence point is reached. At the equivalence point of a neutralization reaction, the moles of acid and moles of base are equal. An indicator, placed in the reaction mixture, tells you by means of a color change, when the equivalence point has been reached. Your experimental data—the volume and molarity of the standard solution and the volume of the unknown acid or base solution—are all that you need to calculate the molarity of the unknown acid or base. 

Generally, acids and bases react according to the rules for replacement and double-replacement reactions given above. They are so important, however, that a special nomenclature has developed for acids and their reactions. Acids were introduced in Sec. 6.4. They may be identified in their formulas by having the H representing hydrogen written first, and in their names by the presence of the word acid. An acid will react with a base to form a salt and water. The process is called neutralization. Neutralization reactions will be used as examples in Sec. 10.5, on titration. 

The acetylium ion is the strongest acid species in the acetic anhydride system, and acetyl fluoborate, which is a good conductor in liquid sulfur dioxide, is a strong acid in acetic anhydride. Acetyl fluoborate, chloride, thiocyanate, and benzene sulfonate may all be titrated as acids in acetic anhydride using sodium acetate, a strong base in that system. 08 The neutralization reaction is ... 

This simple calculation illustrates the fundamental truth underlying neutralization reactions complete reaction requires equal amounts of acid and alkali. In fact, the primary purpose of a titration is to measure an unknown amount of a substance in a sample, as determined via a chemical reaction with a known amount of a suitable reagent. We perform the titration to ascertain when an equivalent amount of the reagent has been added to the sample. When the amount of acid and alkali are just equal, we have the equivalence point, from which we can determine the unknown amount. 

In this chapter, you learned about solutions and how to use molarity to express the concentration of solutions. You also learned about electrolytes and nonelectrolytes. Using a set of solubility rules allows you to predict whether or not precipitation will occur if two solutions are mixed. You examined the properties of acids and bases and the neutralization reactions that occur between them. You then learned about redox reactions and how to use an activity table to predict redox reactions. You learned about writing net ionic equations. Finally, you learned how to use the technique of titrations to determine the concentration of an acid or base solution. 

In a neutralization reaction, moles of H+ ions equal moles of OH ions. This relationship is the basis for the procedure called titration, which you will use to standardize a base solution. Standardizing a base means determining its molar concentration. You will then use your standardized base to determine the molar mass of an acid. To determine when the moles of H+ equal the moles of OH, you will monitor the pH of an acid solution as a solution of base is added slowly. The pH will rise suddenly when the concentrations of the two ions are equal (the equivalence point). 

M Mg(OH)2. This problem gives you Step 6 in the titration procedure and asks you to back-solve for the molarity of the base. Start by finding the number of moles of acid present in the solution by multiplying the molarity (0.50 M) by the volume (0.005 L), giving you 0.0025 mol. Next, examine the balanced neutralization reaction to determine the number of moles of mc -nesium hydroxide needed to neutralize 0.0025 mol HNO2 ... 

The pH of a solution at the stoichiometric point of an acid-base titration depends on the properties of the salt formed in the neutralization reaction. At the stoichiometric point of the titration of formic acid, HCOOH (1), with sodium hydroxide, the solution consists of sodium formate, NaHC02, and water. Formate ion, HC02 (2), is a base, and the Na+ ions have virtually no effect on pH so overall the solution is basic, even though the acid has been completely neutralized. 

To see how titration works, let s imagine that we have an HC1 solution (an acid) whose concentration we want to find by allowing it to react with a base such as NaOH in what is called a neutralization reaction. (We ll learn more about acid-base neutralization reactions in the next chapter.) The balanced equation is... 

The change in pH seen in a / V / titration curve is due primarily to the neutralization reaction, but it is also due to the dilution effect of mixing two solutions. Volume changes constantly during a titration. 

The neutralization reaction goes to completion, but the amount of H30 + added before the equivalence point is not sufficient to convert all the NH3 to NH4+. We therefore have an NH4+-NH3 buffer solution, which accounts for the leveling of the titration curve in the buffer region between the start of the... 

Acid-base titration involves a neutralization reaction between an acid and a soluble base. The reactants may be a strong acid and a strong base, a strong acid... 

The conventional conductometric titration was not suitable for the characterization of these carboxylated latexes because the surface of the latex particles was varied during the titration. In carboxylated latexes, the carboxyl groups located at the particle surface are neutralized and hydrated first, follow ed by the neutralization and hydration of the carboxyl groups located in the inner layers adjacent to the surface, and so on. These sequential reactions seemed to take longer than the experimental time (say, 30 minutes). Verbrugge (4) reported that it took almost two days to get to equilibrium completely. The overall rate of reaction should be controlled by a diffusion process in the neutralization reaction of carboxylated latexes. If this is the case, the rate of reaction must be a function of the distribution of carboxyl groups within the latex particles. 

Consequently, modified conductrimetric titration, which takes into account the time dependence of the neutralization reaction was devised and used in this work, as follows (12). 

In a typical acid-base titration, an acid-base indicator (such as phenolphthalein) or a pH meter is used to monitor the course of a neutralization reaction. The usual goal of titration is to determine an unknown concentration of an acid (or base) by neutralizing it with a known concentration of base (or acid). 

In some ionic liquids, acid (proton) impurities are significant. This is common in the phosphonium cation family of ionic liquids and can also be the case with nitrogen-based cations if the synthetic method involves a neutralization reaction. It is relatively easy to deal with this situation. Acidity should be determined by a standard titration method and then the acidity neutralized by addition of an appropriate base. Carbonates are particularly useful in this regard since they produce CO2 as the product. 

One of the most common titrations of this type is the titration of hydrochloric acid, HC1, with sodium hydroxide, NaOH. If you remember from earlier, this is a neutralization reaction. However, you should also remember from earlier that in order for a complete neutralization to occur, the reaction must use appropriate stoichiometric ratios. When we first look at the process, we will do so with two solutions of known concentration, but you will see that this process can be used to determine the concentration of one of the solutions. 

The acid-base properties of calcium-, copper-, zinc-, and manganese-montmoril-lonites produced from calcium-montmorillonite were studied by potentiometric titration (Nagy and Konya 2004 Nagy et al. 2004). The neutralization reactions of Cu, Zn, and Mn ions can be described by Equations 2.6-2.8 ... 

Electrometric Titration Precipitation Reactions.—One of the most important practical applications of electrode potentials is to the determination of the end-points of various typos of titration the subject will be treated here from the standpoint of precipitation reactions, while neutralization and oxidation-reduction processes are described more conveniently in later chapters. 

Figure 6.3. Titration of H30 and Cu aq with ammonia (a) and with tetramine (trien) (b). Equilibrium diagrams for the distribution of NH3-NH4 (c) of the amino coppeifll) complexes (d) and of Cu ", Cu-trien (e). The similarity of titrating with a base and titrating a metal ion with a base (Lewis acid-base interaction) is obvious. Both neutralization reactions are used analytically for the determination of acids and metal ions. A pH or pMe indicator electrode (glass electrode for and copper electrode for Cu " ) can be used for the end point indication.

Use the following terms to create a concept map hydronium ions (HsO ), hydroxide ions (OH ), neutralization reaction, pH, and titration. 

Explain how neutralization reactions are used in acid-base titrations. 

Acid-base titration The stoichiometry of an acid-hase neutralization reaction is the same as that of any other reaction that occurs in solution. In the antacid reaction you just read about, one mole of magnesium hydroxide neutralizes two moles of hydrochloric acid. 

Titration is the process in which an acid-base neutralization reaction is used to determine the concentration of a solution of unknown concentration. 

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