第5章 酸堿滴定法總結(jié)

1、第,5,章,酸堿平衡和酸堿滴定法小結(jié),一、活度和平衡常數(shù),c,a,i,1,3,0,1,50,0,lg,2,I,I,I,Z,i,i,i,i,i,Z,c,I,2,2,1,1,512,0,lg,2,I,B,I,Z,i,i,I,Z,i,i,2,5,0,lg,m,n,n,m,nB,mA,B,A,K,2,本性有關(guān),僅與溫度及,活度常數(shù),n,m,B,A,n,B,m,A,a,B,A,a,a,a,K,n,m,本性及介質(zhì)條件有關(guān),與溫度,濃度常數(shù),n,m,n,m,n,m,c,a,B,A,B,A,B,A,K,1,n,m,B,A,n,B,m,A,a,c,a,K,K,二者關(guān)系,1,1,2,1,2,1,2,n,n,n,n

2、,n,n,n,n,H,A,a,a,a,a,a,a,H,H,A,c,H,K,H,K,K,H,K,K,K,二,計算,A,H,n,1,1,1,2,1,2,1,1,1,1,2,n,n,n,a,n,n,n,n,n,H,A,a,a,a,a,a,a,K,H,H,A,c,H,K,H,K,K,H,K,K,K,1,2,1,1,2,1,2,0,1,2,n,n,n,n,a,a,a,n,n,n,H,A,a,a,a,a,a,a,K,K,K,A,c,H,K,H,K,K,H,K,K,K,i,i,i,a,i,H,A,H,A,f,H,K,H,A,c,A,HA,pK,pH,a,A,HA,pK,pH,a,A,HA,pK,pH,a,H

3、A,2,1,HA,A,H,pK,pH,a,2,1,HA,A,H,pK,pH,a,2,2,A,HA,pK,pH,a,2,1,2,1,HA,pK,pK,pH,a,a,2,2,A,HA,pK,pH,a,H,2,A,2,1,2,2,1,1,A,H,HA,pK,pK,pH,pK,a,a,a,2,1,2,2,2,1,A,HA,pK,pH,pK,pK,a,a,a,三、質(zhì)子條件與,pH,計算,1,MBE,CBE,PBE,2,pH,的計算,一元強酸,c,mol,L,1,HA,PBE,H,c,OH,6,1,8,1,10,10,w,c,mol,L,H,c,c,mol,L,H,K,a,w,H,c,K,H,精確式,PB

4、E,OH,H,c,W,OH,c,K,OH,一元強堿,c,mol,L,1,NaOH,6,1,8,1,10,10,w,c,mol,L,OH,c,c,mol,L,OH,K,二元強酸,C,mol,L,1,H,2,SO,4,2,2,4,4,OH,SO,HSO,H,PBE,2,2,2,4,a,a,cK,H,c,SO,c,H,K,2,2,2,2,0,a,a,H,K,c,H,cK,1,強酸強堿,2,4,2,近似式,b,b,b,b,K,C,K,K,OH,最簡式,b,b,K,C,OH,10,100,b,b,b,w,b,C,C,K,K,K,且,10,100,b,b,b,w,b,C,C,K,K,K,且,10,100,

5、b,b,b,w,b,C,C,K,K,K,且,簡式,w,b,b,K,K,C,OH,2,4,2,近似式,a,a,a,a,K,C,K,K,H,最簡式,a,a,K,C,H,10,100,a,a,a,w,a,C,C,K,K,K,且,10,100,a,a,a,w,a,C,C,K,K,K,且,10,100,a,a,a,w,a,C,C,K,K,K,且,簡式,w,a,a,K,K,C,H,2,一元弱酸、弱堿,一元弱酸,一元弱堿,3,多元弱酸（弱堿,2,1,2,1,0.05,20,a,n,a,a,a,K,H,A,K,c,K,K,c,若,或,可忽略二級解離，按一元弱酸處理,4,混合酸,弱酸與弱酸混合,例如,C,HA,

6、mol/L HA,C,HB,mol/L HB,H,HA,HB,HA,a,HB,a,c,K,c,K,強酸與弱酸混合,例如,a mol/L HCl,Ca,mol/L HAc,a,Ac,OH,H,PBE,a,K,K,c,a,a,a,a,H,Ac,H,HA,a,HA,HB,a,HB,HA,a,HA,K,C,K,C,K,C,H,時,當(dāng),5,兩性物質(zhì),適合：酸式鹽,HCO,3,弱酸弱堿鹽（如,NH,4,Ac,氨基酸（如,NH,2,CH,2,COOH,類兩性,如,HAc-KF,HB,HB,1,2,1,H,C,K,C,K,K,a,a,a,2,1,H,a,a,K,K,p,p,2,1,pH,2,1,a,a,K,K

7、,HB,HB,2,1,H,C,C,K,K,K,a,w,a,HB,HB,1,2,1,H,C,K,C,K,K,K,a,a,w,a,2,HB,w,10K,a,K,C,1,HB,a,10K,C,2,HB,w,10K,a,K,C,1,HB,a,10K,C,類兩性物質(zhì),C,HA,mol/L HA,C,B,mol/L B,B,HA,B,HA,H,C,C,K,K,C,K,C,K,K,K,HA,HB,B,HA,w,HB,a,K,作為堿的物質(zhì)其共軛酸的,值,作為酸的物質(zhì)的,值,1,a,K,2,a,K,a,K,6,C,a,mol,L,1,HA,C,b,mol,L,1,A,OH,H,OH,H,lg,pH,a,b,a,

8、C,C,pK,H,H,lg,pH,6,pH,a,b,a,C,C,pK,OH,OH,lg,pH,8,pH,a,b,a,C,C,pK,a,b,a,C,C,pK,lg,pH,C,C,b,a,濃度較大時,五、酸堿緩沖溶液,1,緩沖溶液,2,緩沖容量,定義,dpH,dc,2.3,HA,HA,A,c,max,0.58,HA,c,1,a,pK,pH,緩沖范圍,HA-A,3,緩沖溶液由,pH,1,pH,2,可容納酸,或堿的量,2,1,A,A,HA,HA,A,b,A,c,4,緩沖溶液的選擇,42,P,pH,pK,a,是在指定,pH,時衡量一個緩沖體系的重要指標(biāo),標(biāo)準(zhǔn)緩沖溶液,一般緩沖溶液,六、酸堿指示劑,理論變

9、色點,理論變色范圍,實際變色范圍：依靠眼睛觀察。如,MO,H,In,ep,H,In,pK,pH,pK,pH,In,HIn,原理,1,HIn,pK,pH,4,4,1,3,4,3,H,In,pK,指示劑用量,雙色：用量對變色點,pH,無影響，但量大多消耗,T,且顏色變化不敏銳,單色：用量對變色點,pH,有影響,的影響,I,變小,變色點,pH,I,I,Z,pK,pK,pH,HIn,In,HIn,2,0,0,5,0,lg,混合指示劑,作用原理,顏色互補,特點,變色敏銳；變色范圍窄,分類,兩種指示劑混合,指示劑與染料混合,七、酸堿滴定基本原理,1,OH,H,1,繪制,曲線,2)pH,突躍范圍,3,指示劑

10、選擇,a,pH,0,0,1,1,C,a,a,C,V,V,V,V,H,b,a,b,a,0,0,1,1,C,a,a,C,V,V,V,V,OH,a,b,a,b,滴定前,sp,點前,0.1,sp,點,sp,點后,0.1,3,sp,pC,pH,3,14,sp,pC,pH,w,K,H,1,0,L,mol,C,H,2,OH,HA,1,繪制,曲線,2)pH,突躍范圍,3,指示劑選擇,a,a,pK,HA,A,pK,pH,a,a,1,lg,lg,0,0,1,1,C,a,a,C,V,V,V,V,OH,a,b,a,b,滴定前,C,0,mol,L,1,HA,sp,點前,HA-A,0.1,sp,點,A,sp,點后,A,O

11、H,0.1,3,a,pK,pH,sp,pC,pH,11,b,sp,K,C,OH,a,CK,H,a,pH,sp,sp,pC,pC,11,3,sp,a,pC,pK,11,3,3,多元酸和混合酸的滴定,準(zhǔn)確滴定判別式,分步滴定判別式,混酸分步滴定判別式,8,10,i,a,CK,4,1,5,1,10,10,i,a,i,a,i,a,i,a,K,K,K,K,4,10,HB,HB,HA,HA,K,C,K,C,八、終點誤差,1,2,10,10,pH,pH,t,ep,t,HX,E,K,c,ep,ep,t,ep,HX,OH,H,E,c,1,OH,H,ep,ep,t,ep,HA,OH,HA,E,c,1,2,10,1

12、0,pH,pH,t,ep,t,HA,E,K,c,2,OH,HA,1,2,1,2,10,10,pH,pH,t,a,a,E,K,K,2,3,1,2,10,10,2,pH,pH,t,a,a,E,K,K,3,OH,H,3,A,sp,點,pH,的計算,指示劑的選擇,sp,ep,pH,pH,思考題,1,512,0,lg,2,I,B,I,Z,i,i,pm,pm,900,400,2,H,HSO,4,1,Z,2,Z,1,H,HSO,SO,4,2,4,Z,2,4,4,SO,HSO,H,2,4,4,SO,HSO,H,4,HSO,H,1,2,2,1,1,2,2,0,0,a,a,HA,c,c,a,a,H,HA,H,A,

13、K,K,K,K,2,1,1,2,2,0,0,2,c,a,a,A,c,a,a,HA,K,K,K,K,I,Z,2,5,0,lg,2,0.5,4,2,0.5,2,10,10,10,I,A,I,I,HA,2,1,2,2,c,A,a,c,a,HA,K,I,K,3. d, f,4,a,偏低,b,第一化學(xué)計量點,pH,sp,4.7,甲基橙指示劑）結(jié)果不受影響,第二化學(xué)計量點,pH,sp,9.66,酚酞指示劑）結(jié)果偏高,c,強堿滴定弱酸，化學(xué)計量點偏堿性,Na,2,CO,3,被滴定到,NaHCO,3,多消,耗,0.2%NaOH,5. HAc: K,a,1.8,10,5,6. H,2,CO,3,pK,a1,6.

14、38 pK,a2,10.25,pH = 10.50 CO,3,2,主,HCO,3,pH = 6.00 H,2,CO,3,主,HCO,3,pH,4.0 H,2,CO,3,CO,2,H,2,O,7,變小,變色點,pH,I,I,Z,pK,pK,pH,HIn,In,HIn,2,0,0,5,0,lg,8. a. 2,個,b,1,個,c,1,個,d,2,個,e,2,個,f,1,個,9,HCl+H,3,BO,3,NaOH(V,1,MR,H,3,BO,3,甘油,NaOH(V,2,HCl+NH,4,Cl,NaOH(V,1,MR,NH,4,Cl,甲醛,NaOH(V,2,Na,3,PO,4,Na,2,HPO,4,H

15、PO,4,2,HCl(V,1,pp,HCl(V,2,MO,H,2,PO,4,Na,3,PO,4,NaOH,HPO,4,2,HCl(V,1,pp,HCl(V,2,MO,H,2,PO,4,NaHSO,4,NaH,2,PO,4,H,2,PO,4,NaOH(V,1,MO,NaOH(V,2,pp,HPO,4,2,H,2,SO,4,H,3,PO,4,H,2,PO,4,NaOH(V,1,MO,NaOH(V,2,pp,HPO,4,2,13,Na,3,PO,4,Na,2,CO,3,H,2,PO,4,HCl(V,1,pp,NaOH(V,2,MO,H,2,PO,4,H,2,CO,3,14,緩沖溶液的緩沖能力與,pH

16、,值（或分布分?jǐn)?shù)）及總濃度有關(guān),15,混合指示劑優(yōu)點：變色敏銳；變色范圍窄,HPO,4,2,例題,1,用,0.100mol,L,1,NaOH,滴定,0.100mol,L,1,HAc,至,pH=6,求終點誤差,解,ep,ep,t,ep,HA,OH,HAc,E,c,1,2,10,10,pH,pH,t,ep,t,HA,E,K,c,ep,ep,HAc,HAc,a,ep,H,HAc,c,c,K,H,8,10,10,ep,OH,H,6,而,由定義,6,8,5,6,10,10,0.0500,1.8,10,10,100,5.3,0.0500,t,E,例題,2,用,0.1000mol,L,1,NaOH,滴定,0

17、.1000mol,L,1,HCl,和,0.2000mol,L,1,H,3,BO,3,混合溶液，,1,計算化學(xué)計量點時溶液的,pH,值；,2,若滴定終點比化學(xué)計量點高,0.5,個,pH,單位，計算終點,誤差,3,化學(xué)計量點和終點各有百分之幾的,H,3,BO,3,參加了反應(yīng),解,10,w,5.8,10,0.100010K,a,K,c,10,0.1000,100,5.8,10,a,c,K,1,化學(xué)計量點時,0.1000mol,L,1,H,3,BO,3,溶液,10,6,5.8,10,0.1000,7.6,10,a,H,K,c,5.12,sp,pH,2,5.62,ep,pH,設(shè)過量,NaOH,量為,c,

18、b,2,3,2,3,b,PBE,c,H,OH,H,BO,H,BO,2,3,100,100,b,t,ep,ep,HCl,HCl,c,H,BO,H,E,c,c,3,5.12,sp,pH,5.62,ep,pH,2,3,100,a,H,BO,a,K,H,K,1,PBE,a,H,= OH,+ NH,3,c,1,或,H,+ NH,4,c,2,OH,b. H,c,1,H,2,BO,3,OH,c. H,= H,2,PO,4,+ 2HPO,4,2,+ 3PO,4,3,+ HCOO,OH,d. H,= OH,或,H,= OH,Fe(OH,2,2Fe(OH,2,3Fe(OH,3,2,10,a,w,cK,K,100,

19、a,c,K,10,5,5.8,10,0.10,0.76,10,a,H,K,c,5.12,pH,a,b,2,2,4,4,OH,SO,HSO,H,PBE,2,2,2,4,a,a,K,H,CK,C,SO,C,H,0,2,2,2,2,a,a,CK,H,C,K,H,0.96,pH,c,10,5.8,10,a,K,10,b,w,cK,K,100,b,c,K,7,5.8,10,b,K,7,4,5.8,10,0.10,2.41,10,b,OH,K,c,3.62,pOH,10.38,pH,2,d,w,K,PBE,H,c,OH,c,H,6.89,pH,e,1,100,a,c,K,3,3,2,3,2,7.6,10,

20、7.6,10,4,7.6,10,0.20,3.52,10,2,1.45,pH,2,1,0.05,a,a,K,cK,6,8,1.0,10,1.0,10,c,14,8,1.0,10,5.0,10,H,H,1,2,3,3,8,13,7.6,10,6.3,10,4.4,10,a,a,a,K,K,K,1,10,a,w,cK,K,1,1,1,2,4,2,a,a,a,K,K,K,c,H,3,a. Ac,K,b,K,w,K,a,5.6,10,10,c,K,b,5.6,10,10,0.050 = 2.8,10,11,10K,w,c,K,b,100,故使用最簡式,OH,= = 5.29,10,6,pH = 14,

21、pOH = 8.72,c. NH,4,K,a,5.6,10,10,HCN K,a,6.2,10,10,cK,a,10K,w,c 10 K,a,由近似公式可以得到,H+ = = = 5.89,10,10,pH = 9.23,a,a,K,K,20,6.2,5.6,10,10,5.6,10,0.05,e,氨基乙酸一端羧基顯酸性，一端氨基顯堿性,K,a1,4.5,10,3,K,a2,2.5,10,10,cK,a2,10K,w,且,c 10 K,a1,所以,H,= = = 1.06,10,6,pH = 6-0.03 = 5.97,g,對于雙氧水而言,Ka = 1.8,10,12,cK,a,10K,w,c

22、/K,a,100,所以可以計算氫離子濃度,H+ = = = 1.67,10,7,pH = 7-0.22 = 6.78,a,w,cK,K,14,14,1.8,10,1,10,1,2,a,a,K,K,13,4.2,2.5,10,i,解,1. 0.050mol/L,的,ClCH,2,COONa(NaA,和,0.060mo/LHCl,的,混合溶液,PBE: HA+H,OH,Cl,0.06,解,2,由于,ClCH,2,COONa + HCl = ClCH,2,COOH + NaCl,所以原溶液可以看成,0.050mol/L,的,ClCH,2,COOH(HA,和,0.010mo/LHCl,的混合溶液,PB

23、E: H,A,Cl,OH,A,0.01,0.06,HA,a,H,c,H,H,K,0.01,a,HA,a,K,H,c,H,K,3,10,a,w,cK,K,100,a,c,K,9.26,5,10,0.05,1.67,10,a,H,K,c,5.28,pH,b,d,9.70,pH,14,9.26,4.74,10,10,10,w,a,b,K,K,K,2,3,8,13,6.3,10,4.4,10,a,a,K,K,3,2,10,a,w,a,cK,K,c,K,c,2,3,2,10,2.01,10,a,a,w,a,K,cK,K,H,K,c,3,11,10,3,2,3,4,1.8,10,5.6,10,a,a,CH

24、,CH,NH,HA,K,NH,HB,K,1,10,b,w,cK,K,1,100,b,c,K,f,h,1,2,14,15,10,1.41,7.1,10,w,b,a,K,K,K,2,1,14,8,7,10,7.69,10,1.3,10,w,b,a,K,K,K,2,1,0.05,b,b,K,cK,1,1,1,2,4,2,b,b,b,K,K,K,c,OH,12.97,pH,6,5.33,10,HA,HA,HB,HB,H,K,c,K,c,5.27,pH,a. HSO,4,K,a2,1.0,10,2,HAc K,a,1.8,10,5,均為弱酸，且濃度遠(yuǎn)低于,HCl,的濃度，所以此體系中,的,HSO,4,和

25、,HAc,在計算,pH,值時刻忽略。故,pH=1.00,b,加入等體積,0.1mol/LNaOH,溶液,HCl,被中和，體系,變?yōu)?HSO,4,和,HAc,的混酸體系,忽略,K,W,及,K,HA,HA,H,2,C,HSO4,H,解得,H,9.90,10,5,故,pH=4.00,或,PBE H,SO,4,2,OH,SO,4,2,4,4,HA,W,HSO,H,K,HSO,K,HA,K,5,6,f,1,2,2,1,2,2,4,14,9.8,14,12.8,b,a,b,a,C,O,pK,pK,pK,pK,1,2,2,1,2,3,14,3.8,14,7.6,b,a,b,a,CO,pK,pK,pK,pK,

26、1,2,1,1,2,2,4,3,3,0.02,0.04,0.06,mol,L,C,O,mol,L,HCO,mol,L,CO,2,2,2,2,4,3,2,4,3,2,2,H,C,O,CO,C,O,HCO,1,1,2,3,3,0.04,0.06,mol,L,HCO,mol,L,CO,2,3,2,3,lg,10.38,CO,a,HCO,c,pH,pK,c,7,3.8,2,5.8,a,K,10,10,10,10,W,c,K,1.8,a,10,100,K,c,2,a,a,a,3,K,K,4K,1.182,10,2,c,H,2,3.8,a,3.8,2.93,a,K,10,0.12,10,10,K,Cr,O

27、H,H,1,mol/L,故,pH=2.93,2,8,設(shè)需加入,NaAc,固體,x,mol,lg,b,a,a,c,pH,pK,c,0.010,4.44,4.74,lg,0.010,x,0.15,x,mol,0.15,82.03,1.23,NaAc,m,g,9,200,0.05,40,100,NaOH,C,0.35,5.30,lg,5.44,0.25,解,mol/L,已知,pK,a,5.30,pH=5.60,設(shè)原緩沖溶液中鹽的濃度為,x,mol/L,故,則原緩沖溶液,pH,x,0.35,0.05,5.60,5.30,lg,0.25,0.05,x,11,解：設(shè)酸以,HA,表示,pK,a1,2.35

28、pK,a2,9.60,1,需,HA,質(zhì)量,m=0.10,0.10,75.0,0.75,g,2,因為氨基乙酸及質(zhì)子化氨基乙酸構(gòu)成緩沖溶液，設(shè),pH=2,時，質(zhì)子化氨基乙酸濃度為,x,mol/L,則,解得,x,0.079,生成,0.079mol/L,的質(zhì)子化氨基乙酸，需加酸為,0.079,100=7.9ml,0.1,2.00,2.35,lg,x,H,x,H,1,2,lg,HA,a,H,A,c,H,pH,pK,c,H,13,解,a. pK,a1,3.04,pK,a2,4.37,1,1,0.034,1,0.034,0.034,2,I,mol/L,2,500,B,a,2,0.51,B,2,0,0,1,2

29、,1,2,2,1,a,a,a,a,H,B,H,K,K,K,K,pH=3.56,2,w,10K,a,cK,1,10,a,c,K,1,2,2,0,0,a,a,H,H,B,K,K,a,H,2,0.034,lg,0.512,1,1,0.00328,500,0.034,H,3.04,4.37,10,10,0.51,H,a,13,解,b. pK,a1,3.04,pK,a2,4.37,2,w,10K,a,cK,1,10,a,c,K,2,0.0500,lg,0.50,1,0.3,0.0500,1,0.0500,H,2,1,2,0,0,1,lg,2,a,a,B,pH,pK,pK,2,2,1,0.0500,1,0

30、.0500,1,0.0500,2,I,2,0.465,B,13,解,c. H,3,BO,3,c = 0.0100 mol/L,pK,a,9.24,查表得,故,pH=9.18,1,0.0200,1,0.0200,1,0.02,2,I,2,4,7,2,3,3,2,3,5,2,2,B,O,H,O,H,BO,H,BO,2,3,400,H,BO,a,2,3,0.869,H,BO,2,3,2,3,3,3,lg,lg,H,BO,a,a,H,BO,H,BO,a,pH,pK,pK,a,2,3,2,0.02,lg,0.512,1,1,0.00328,400,0.02,H,BO,15,依題意,1,1,2,1.92,

31、1.2,10,a,a,a,pK,K,2,1,7,6.22,6.02,10,a,a,pK,K,2,1,1,10,10,a,w,a,b,sp,HB,cK,K,c,K,1,2,1,a,a,a,cK,K,H,c,K,4.12,pH,1,2,2,1,2,2,14,7.78,14,12.08,b,a,b,a,sp,B,pK,pK,pK,pK,2,1,1,1,0.05,10,100,b,b,w,b,b,K,c,cK,K,K,cK,1,b,OH,cK,9.37,pH,4.63,pOH,16,依題意,3,2,5,10,10,a,K,c,a,H,K,c,9,10,w,b,a,K,K,K,9,1,5,10,10,1

32、0,b,OH,K,c,14.0,5.0,9.0,pH,10,b,w,K,c,K,100,b,c,K,17,設(shè),Na,2,CO,3,的量為,x g,則,NaHCO,3,的量為,0.685,x g,0.685,2,0.200,0.0500,106.0,84.00,x,x,0.200,106.0,x,V,12.5,V,ml,解得,18,lg,b,a,a,c,pK,pH,c,0.1100,11.00,4.8,lg,4.89,0.1100(24.6,11.00,19,sp,時,1,0.05,NaOH,c,mol,L,10,5.6,10,w,b,a,K,K,K,20,b,w,K,c,K,500,b,c,K,6,5.29,10,b,OH,K,c,14,6,0.72,8.72,sp,pH,8.00,8.72,0.72,ep,sp,pH,pH,pH,0.72,0.72,10,10,100,ep,a,HB,w,TE,K,c,K,8,0.19,5.25,100,0.05,1.8,10,0.05,100,ep,ep,t,ep,OH,HAc,E,c,ep,ep,ep,a,c,H,HAc,c,H,K,20,sp,時,1,0.05,NaOH,c,mol,L,1,