Copy_of_Salt_Hydrolysis_and_Titrations_note.docx - SCH4U...

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SCH4U – Chemical Equilibrium Salt Hydrolysis and Titrations SALT HYDROLYSISWhen added to water, salts __disocciate ____________ into ____ions __________If these ions react with H2O by taking a proton or by giving a proton then the pH of the solution will be affected.These ions are said to __hydrolyze____________There are several different ways to classify/predict the affect this dissociation of ions will have on the pH of the solution.We must consider _____both_________ ions from the salt in order to determine the effect on pH of an aqueous solution.SALTS THAT PRODUCE NEUTRAL SOLUTIONSWhen you test solution of sodium chloride with a pH meter, the reading is 7or ___netural ___________. Anion of a strong acid (acid’s conjugate base) has virtually no affinity for _hydrogen ions _____________ ______________.Cation of a strong base has virtually no affinity for __hydroxide ions ____________ ______________. Dissociated ions therefore do no react with water and do no change balance of [H3O+] or [OH-] in H2O so solution is neutral, pH=7SALTS THAT PRODUCE BASIC SOLUTIONSConsider a sodium acetate solution:NaC2H3O2= Na +c2h3o2 (dissociation)c2h3o2+h2o= hc2h3o2+ oh ( hydrolysis) Since Na+is the cation of a strong base – NaOH(aq) – it does not react with water to form NaOH(aq) and H+Acetate ion, C2H3O2-is the anion(conjugate base) of a weak acid – acetic acid, HC2H3O2– thereforeit is a sufficiently strong base to react with water to produce HC2H3O2and OH-. No H+ions produced; some OH-ions produced_basic solution _____________DETERMINING THE pH OF A BASIC SALT SOLUTIONCalculate the pH of a 0.30 mol/L sodium nitrite solution, NaNO2(aq).

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