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Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,4/1/2012,#,Acid-Base ReactionsCh. 15,Acid-Base Reactions,Neutralization reactions,中和反应,pH is changed,Produce a,salt and H,2,O,Salts are ionic compounds,2 types of Acids,Strong and Weak,2 types of Bases,Strong and Weak,4 possible combinations of Acids and Bases,Strong A + Strong B,Strong A + Weak B,Weak B + Strong B,Weak B + Weak A,Strong Acid + Strong Base,HCl + NaOH, NaCl + HOH,Double replacement reaction,Both compounds completely dissociate,HCl Cl,-,+ H,+,NaOH Na,+,+ OH,-,Complete equation,(,aq,),can be written:,H,+,+Cl,-,+Na,+,+OH,-,Cl,-,+Na,+,+H,2,O,Spectator Ions,Ions that,do not,take part in the reaction,Net Ionic Equations,净离子方程式,1) Write Complete Ionic Equation,All soluble compounds are shown as free ions,2) Remove Spectator Ions,Ions not directly evolved in the rxn.,3) Balance the remaining rxn.,Strong Acid + Strong Base,What is the net ionic equation:,HCl,(aq),+ NaOH,(aq),1),H,+,(aq),+Cl,-,(aq),+Na,+,(aq),+OH,-,(aq),Cl,-,(aq),+Na,+,(aq),+H,2,O,(aq),2),H,+,(aq),+OH,-,(aq), H,2,O,(l),All strong acid and strong base reactions have this as a,base net ionic equation,KOH,(aq),+HNO,3(aq),KNO,3(aq),+H,2,O,(l),K,+,+OH,-,+H,+,+NO,3,-, K,+,+NO,3,-,+H,2,O,(l),OH,-,+H,+,+ H,2,O,(l),Strong Acid + Weak Base,HCl,(aq),+ Al(OH),3(s),Weak bases wont completely dissociate,Cannot write them as ions on reaction side of net ionic equation,H,+,(aq),+Cl,-,(aq),+Al(OH),3(s),Al,+3,(aq),+Cl,-,(aq),+H,2,O,(l),H,+,(aq),+Al(OH),3(s),Al,+3,(aq),+H,2,O,(l),End solution is slightly acidic,What about NH,3,?,Considered a weak base but has no OH,-,Does not produce water,HCl,(aq),+NH,3(aq),NH,4,Cl,(aq),H,+,(aq),+Cl,-,(aq),+NH,3(aq),NH,4,+,+Cl,-,(aq),H,+,(aq),),+NH,3(aq),NH,4,+,Weak Acid + Strong Base,HC,2,H,3,O,2(aq),+ NaOH,(aq),Weak acid wont completely dissociate,Wont breakdown into ions on reaction side,HC,2,H,3,O,2(aq,),+,Na,+,(aq),+OH,-,(aq),Na,+,(aq),+C,2,H,3,O,2,-,(aq),+ H,2,O,(l),HC,2,H,3,O,2(aq,),+,OH,-,(aq),C,2,H,3,O,2,-,(aq),+ H,2,O,(l),End solution is slightly basic,Weak Acid + Weak Base,?Not clear?,Both the acid and base are so unreactive there is little change,Not common reaction type in nature,Bronsted-Lowery Acids and Bases,Acids produce H,+,ions when added to water,Bases produce OH,-,ions when added to water,HCl,(aq),+H,2,O,(l),H,3,O,+,(aq),+Cl,-,(aq),H,2,O,(l),+NH,3(aq),NH,4,+,(aq),+OH,-,(aq),Acid= Any compound that releases H,+,Base= Any compound that takes H,+,Water can act as an acid or a base,Conjugate Acid/Base,Weak acid or base produced from an acid-base reaction,ACID,BASE,ACID,BASE,Conjugate acid,Conjugate acid,Conjugate base,Conjugate base,Regulating pH,Living things interact with acids and bases all the time; their,pH must be regulated,Buffer,Solution that adjusts to the addition of acids and bases to,slowly,change the pH,Free OH,-,and H,+,ions,Weak acid/base + salt of that acid/base,NaOH +,HC,2,H,3,O,2,H,2,O +,NaC,2,H,3,O,2,NaC,2,H,3,O,2,and HC,2,H,3,O,2,Add a strong base:,H,C,2,H,3,O,2(aq),+NaOH,(aq),C,2,H,3,O,2,-,(aq),+H,2,O,(l),HC,2,H,3,O,2(aq),+OH,-,(aq),C,2,H,3,O,2,-,(aq),+,H,2,O,(l,),Add a strong acid:,NaC,2,H,3,O,2(aq),+HCl,(aq),HC,2,H,3,O,2(aq),+NaCl,(l),C,2,H,3,O,2,-,(aq),+H,+,(aq),HC,2,H,3,O,2(aq),Buffers in the Blood,Blood must keep a pH of,7.4,to allow the best exchange of CO,2,and O,2,Blood buffer is HCO,3,-,/H,2,CO,3,Add Base: H,2,CO,3,+OH,-,HCO,3,-,+,H,2,O,Add Acid: HCO,3,-,+H,+,H,2,CO,3,What happens when you take in too much CO,2,?,H,2,CO,3,increases making blood more acidic,What kind of blood pH results in yawning?,Acidic blood; body needs to release large amount of CO,2,by taking in large amount of O,2,Antacids,抗酸剂,Compound controls acidic pH levels by adding base,2 types:,Hydroxide,Antacids,Low solubility in water,Release OH,-,to neutralize H,+,Milk of Magnesia (Mn(OH),2,),Carbonate,Antacids,XCO,3,or XHCO,3,; react with HCl,CaCO,3,+ 2HCl,CaCl,2,+,H,2,CO,3,Breaks down to CO,2,and H,2,O,Titrations,滴定,Test to determine the molarity of an acid or a base,Find the Standard Solution,标准溶液,Process:,Standard solution of an acid/base is slowly added to an acid/base of unknown molarity,When the unknown acid/base is,neutral, the H,+,=OH,-,How do we know the Standard solution is neutral?,pH Indicators,酸碱指示,剂,Volume of acid/base used gives us molarity,M,A,V,A,= M,B,V,B,End point,Equivalence point,Neutral point,Titrations practice,If 15.0 mL of 0.50 M NaOH is used to neutralize 25.0 mL of HC,2,H,3,O,2, what is the molarity of the acid solution,?,NaOH + HC,2,H,3,O,2,H,2,O + NaC,2,H,3,O,2;,1:1 ratio,M,A,V,A,= M,B,V,B,M,A,= M,B,V,B,/V,A,= (0.50 M)(15.0 ml)/25.0 ml =,0.30 M,If 25.0 mL of a standard 0.05 M HCl solution is required to neutralize 20.0 mL of a solution of Sr(OH),2, what is the concentration of the base?,2,HCl + Sr(OH),2,SrCl,2,+,2,H,2,O;,2:1 ratio,M,A,V,A,=,2,M,B,V,B,M,B,= M,A,V,A,/2V,B,= (0.05 M)(25.0 ml)/(2)(20.0 ml),= 0.03 M,Titrations practice,What types of acid-base reactions do these titration graphs show?,Titrations practice,Graphs shows titration of 0.5 M NaOH with 50ml of an unknown acid. After titration NaBr salt crystals were isolated from the solution.,a) What is the acid used? Is it strong or weak?,b) what is the concentration of the acid used?,HBr,:,NaOH + HBr, NaBr + H,2,O;,strong,M,A,= M,B,V,B,/V,A,= (0.5M)(35ml)/50ml,= 0.35 M,
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