Hydrolysis and Neutralization Acids and Bases: salt hydrolysis pH 7 pH 8.9 pH 5.3 Hydrolysis and Neutralization

C12-5-11 NEUTRALIZATION AND SOLUTION OUTCOME QUESTION(S): C12-5-11 NEUTRALIZATION AND SOLUTION Write balanced neutralization reactions involving strong acids and bases. Using a standardized acid or base, determine the concentration of an unknown base or acid. Predict whether an aqueous solution of a given ionic compound will be acidic, basic or neutral given the formula. Vocabulary & Concepts salt hydrolysis

Neutralization reaction Acid + Base H2O + salt Salt: ionic compound produced by reacting acid with base HCl(aq) + NaOH(aq) H2O(l) + Na+ Cl- (aq) Hydrolysis: breakdown by water Salt Hydrolysis: The produced salt dissociates in solution and may react with water to produce an acidic/basic solution. When a reactant in the neutralization is weak it will generally result in a solution that is NOT neutral. 

Na+ Cl- HCl(aq) + NaOH(aq) H2O(l) + 3 possible neutralization outcomes: Strong Acid + Strong Base HCl(aq) + NaOH(aq) H2O(l) + Na+ Cl- (aq) Acid to Base Base to Acid Water is neutral Na+ is unreactive Cl- is unreactive Equivalence results in neutral solution pH = 7 No product has characteristics of an acid/base Strong acid/base leave behind weak conjugates

NH4+ is a strong conjugate acid created from weak base NH3 Strong Acid + Weak Base NH3(aq) + HNO3(aq) H2O(l) + NH4+ NO3- (aq) NH4+ is a strong conjugate acid created from weak base NH3 NH4+(aq) + H2O (aq) H3O+(aq) + NH3 (aq) Acid to Base Base to Acid Note: sloppy s-curves Equivalence results in acidic solution pH < 7 A strong conjugate acid has been produced

CH3COO- is a strong conjugate base created from weak acid CH3COOH Weak Acid + Strong Base CH3COOH(aq) + NaOH(aq) H2O(l) + Na+ CH3COO- (aq) CH3COO- is a strong conjugate base created from weak acid CH3COOH CH3COO-(aq) + H2O (aq) OH-(aq) + CH3COOH (aq) Acid to Base Base to Acid Note: sloppy s-curves Equivalence results in basic solution pH > 7 A strong conjugate base has been produced

Anions of strongest acids are unreactive: What to look for: Anions of strongest acids are unreactive: Cl-, ClO4-, I-, Br-, NO3- (weakest CBs) Metal cations of strongest bases are unreactive: Alkali (I) and Earth (II) metals (weakest CAs) SALT Cation Anion Is it a group I or II metal? Is it part of a strong acid? YES NO NO YES No effect (neutral) No effect (neutral) Could hydrolyze WILL hydrolyze

It says “could” because not all metal cations will affect pH SALT Cation Anion Is it a group I or II metal? Is it part of a strong acid? YES NO NO YES NO effect (neutral) Na+ K+ Mg2+ (etc.) Could hydrolyze NH4+ Fe3+ Sn2+ (etc.) NO effect (neutral) ClO4- I- NO3- (etc.) WILL hydrolyze O2- F- NO2- (etc.) It says “could” because not all metal cations will affect pH Notice: Cations generally create acidic solutions, while anions generally create basic solutions

Both solutions are basic Are K2CO3 and MgS acidic, basic or neutral? Step 1. Identify the ions present: How will they dissociate in water? Look for the anions on the Strength Chart… No effect (Group I) No effect (Group II) K2CO3(s) → 2 K+(aq) + CO32–(aq) MgS(s) → Mg2+(aq) + S2–(aq) Strong conjugate base of weak acid HCO3- Strong conjugate base of weak acid HS- Step 2. Determine if each ion will affect the pH: What acid or base reaction did it come from? CO32-(aq) + H2O (aq) OH-(aq) + HCO3- (aq) Both solutions are basic S2-(aq) + H2O (aq) OH-(aq) + HS- (aq)

C12-5-11 NEUTRALIZATION AND SOLUTION CAN YOU / HAVE YOU? C12-5-11 NEUTRALIZATION AND SOLUTION Write balanced neutralization reactions involving strong acids and bases. Using a standardized acid or base, determine the concentration of an unknown base or acid. Predict whether an aqueous solution of a given ionic compound will be acidic, basic or neutral given the formula. Vocabulary & Concepts salt hydrolysis