Salts and Titration.docx - Salts When an acid and a base...

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SaltsWhen an acid and a base react, water and a salt are formed. A salt is an ionic compound that results from an acid-base reaction. A chemical reaction between an acid and a base that yields a salt and water is called a neutralization reaction.Salts are strong electrolytes that completely ionize in water and they often affect the pH of a solution. The pH of the salt solution can be neutral, acidic, or basic. When the salt dissociates or splits apart in water, an anion, a negatively charged ion, and a cation, a positively charged ion, form. The process in which salt reacts with water is called salt hydrolysis.Neutral Salt SolutionsWhen a salt consisting of an anion of a strong acid or a cation of a strong base reacts with water, hydrolysis, or a reaction with water, usually does not occur. For example, when a strong acid, such as nitric acid, HNO3(ℓ), dissolves in water, the acid completely dissociates and ionizes as shown below:Water is a much stronger conjugate base than the nitrate ion, NO3(aq), so the reaction essentially goes to completion.Consider the ionization of a strong base in water, such as sodium hydroxide, NaOH(s),as shown below:Recall that the H2O written above the yield arrow indicates that water is required as the solvent, but water is not considered a reactant. The sodium ion, Na+(aq), does not react further with water and cannot donate or accept a proton. The solution is neutral, with a pH of about 7. The positively charged ions, or cations, from all strong bases behave in this same way.Acidic Salt SolutionsWhen a salt consisting of the anion of a strong acid and the cation of a weak base ionizes in water, the solution is acidic because the cation acts as a weak acid. When ammonium chloride, NH4Cl(s), dissolves in water, as shown below, the chloride ions, Cl(aq), do not react with water because the ion is a very weak base.The ammonium ion, NH4+(aq), is a weak Brønsted-Lowry base that does react with water, as shown below:Because hydronium ions are produced, the solution is acidic.Basic Salt Solutions

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