Acid Base Reactions and Salts 10.7-10.8

Acid – Base Reactions A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.

Equations With Acids Acids undergo characteristic double replacement reactions with oxides, hydroxides, carbonates and bicarbonates. e.g. 2HCl (aq) + CuO (s)  CuCl2 (aq) + H2O (l) 2HCl (aq) + Ca(OH)2 (aq)  CaCl2 (aq) + 2H2O (l) 2HCl (aq) + CaCO3 (aq)  CaCl2 (aq) + H2O (l) + CO2 (g) 2HC l (aq) + Sr(HCO3)2 (aq)  SrCl2 (aq) + 2H2O (l) + 2CO2 (g)

Equations With Acids Bases undergo a double replacement reaction with acids called neutralization: NaOH (aq) + HCl (aq)  H2O (l) + NaC l (aq) In words this well known reaction is often described as: “acid plus base = salt plus water” We previously discussed this reaction when describing types of reactions.

Acidic Single Replacement Reactions Another property of acids is their reaction with certain metals to produce hydrogen gas, H2 (g). Zn (s) + 2HC l (aq)  H2 (g) + ZnCl2 (aq) This is an example of a single replacement reaction and is a redox reaction. Total ionic equation: Zn (s) + 2H+ (aq) + 2Cl- (aq)  H2 (g) + Zn2+ (aq) + 2Cl- (aq) Net ionic equation: Zn (s) + 2H+ (aq)  H2 (g) + Zn2+ (aq)

Acid – Base reactions Each salt listed in this table can be formed by the reaction between an acid and a base.

Salts Salts are the ionic product of an acid base neutralization reaction. Acidic Salts are formed from a strong acid and a weak base. Neutral salts are formed from a strong acid and strong base. Basic salts are formed from a strong base and a weak acid. Give the acid and base the following salts were formed from and label the salts as acidic, basic, or neutral. NaCl NaC2H3O2 NH4Cl HCl + NaOH NaCl + HOH neutral salt s.a. s.b. HC2H3O2 + NaOH NaC2H3O2 + HOH basic salt w.a. s.b. HCl + NH4OH NH4Cl + HOH acidic salt s.a. w.b.

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