单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,5.4 酸碱滴定类型及指示剂的选择,5.4.1 强酸强碱相互滴定,一、反响产物及指示剂,产物是水，化学计量点pH7.00，,指示剂可选用：,甲基橙pH=3.13.4，甲基红(pH=4.46.2，酚酞pH=8.010.0等。,二、NaOH滴定HCl,以0.1000mol/L NaOH滴定20.00mL 0.1000 mol/L HCl为例讨论强酸强碱相互滴定的滴定曲线和指示剂选择。,按以下七个局部进行来讨论：,1、滴定前,溶液的酸度等于HCl的原始浓度 H,+,=0.1000mol/L,pH=1.00,2、滴定开始至化学计量点前,溶液的酸度取决于剩余HCl的浓度，,例如当,滴入NaOH溶液18.00mL时：,即pH2.28,2、滴定开始至化学计量点前(续),当,滴入NaOH溶液19.98mL时,剩余HCl的浓度为:,3.化学计量点时,滴入NaOH,20.00mL,时，有：,H,+,=OH,=1.0010,-7,mol/L,pH=7.00,4.化学计量点后,溶液的碱度取决于过量的NaOH体积，例如滴入NaOH 20.02mL过量了0.02 ml 时，有：,同样的，可以计算出滴入不同体积的NaOH溶液的pH值，计算结果列于下表：,pOH4.30,pH144.309.70,表,加入体积(mL),中和百分数,过量体积(mL),pH值,0.00,0.00,1.00,18.00,90.00,2.28,19.80,99.00,3.30,19.98,99.90,剩余0.02,4.31A,20.00,100.0,7.00,20.02,100.1,0.02,9.70B,20.20,101.0,0.20,10.70,22.00,110.0,2.00,11.70,40.00,200.0,20.00,12.50,用0.1000 mol/L NaOH 滴定20.00mL 0.1000 mol/L HCl,的数据计算结果列表,滴定突跃,5、滴定曲线1,以NaOH的参加量或中和百分数为横坐标，以pH 值为纵坐标来绘制曲线，就得到酸碱滴定曲线如下图,续上,从滴定开始到参加19.80 mL时，溶液pH值只改变2.3个单位,再参加0.18 mL，pH就改变了1个单位，变化速度加快了,再滴入0.02mL约半滴，正好是化学计量点此时共参加20.00mL，此时pH迅速升至7.0。再滴入0.02mL，pH值为9.70。此后过量的参加所引起的pH变化又越来越小。,续上,由此可见，在化学计量点前后，从剩余0.02mL HCl到过量0.02mL NaOH，即滴定由缺乏0.1到过量0.1%，溶液的pH值由4.30升至9.70，变化近5.4个单位，形成滴定曲线的“突跃局部。指示剂的选择主要就以此为依据。,6、强酸强碱相互滴定的指示剂,显然，最理想的指示剂应该恰好在化学计量点上变色。,而实际上酸碱指示剂的选择原那么是:,指示剂的变色范围落在或者局部落在滴定曲线的 pH 突跃范围之内。,续1,在以0.1000 mol/L NaOH 滴定20.00mL 0.1000 mol/L HCl 时：,凡在,pH 4.309.70 以内变色的指示剂,，都可以保证测定有足够的准确度,。,如甲基红，酚酞等,。,续2,如果改用0.1000mol/L HCl滴定0.1000mol/L NaOH，滴定曲线形状与右图相同，但位置相反。,指示剂仍选甲基红，甲基橙。,6、强酸强碱相互滴定的指示剂续3,酸碱互滴，一般可以根据滴定至化学计量点时溶液的 pH 值来选择指示剂，那么：,当滴定至化学计量点时，溶液的 pH 值呈碱性，可以选择酚酞；,当滴定至化学计量点时，溶液的 pH 值呈酸性，可以选择甲基橙。,7、影响滴定曲线突跃大小的因素,强酸强碱相互滴定，其滴定曲线突跃的大小与溶液的浓度和强度有关，不同浓度的NaOH和HCl的滴定曲线如右图所示。酸碱浓度增大10倍，突跃局部pH值变化范围增加约2个单位。而浓度小了，突跃也小了，那么指示剂的选择也就会受到限制。,Igy+usEC-BVv6r)wARWp0ra&o4O%mDj6MJHhd3zaJHNCU3-fsa8*iN$z8v3ITar7)HKQzFIh7Is1!mOsTd+FjxASGqwe-b59L2HSZgjoU+l6PC&hLs9y6GJYZmY7PmD3wsAvXl(sYKcV#SXv(QaDmUa9noWsPt9zaPZe5vMckqV*aTeUHJsERHSZCul4PH6CmUliDNn7KGFefjR-of*H4FTlU#i4qA!XOHRZFCqQf%cr!2jOr(3a6H3Tb(cK1*vEgXOjRYeycdsbXQaFIAjzBQ0puZa4Ns*)Xa#ObH6G0-kjUlKq8&gHsARy9CD-LKErM8vIDFebN+#yB41q9B2g1q*5a4kD#FiCuD%tSc2A%)v(R8)Y*+t80HJbNEH0R7b$BAhsqBKRBJ8qf631T87zm(TCJXk(z(ZxMFS!B*p)tgdyMP1jC!JGhoKby&bfu3FzX$pT)duGl-F%KO*JLd9WwouDxMjOSthETlca4ppR!mCE4XfGfH7$*UMIIba-WQE-%mHK!XSJ(z8RcMw9*GX5i(iMDJ3DVVdALGm*i0(sdXYpY76axHD*cs&a&8ie2mnohd$Tp+QR8(HzlkljTj$luyj!oIBTS0HOIN$#CpX5d$%&IfzBlon&qpc!XVSSiYf72YG)uY-N4jU3MAk)5(AMZ1AUgUCpN&FvS6fVng$HMW-TahTbfW(WIR3+WdSB1ZXzyx38sUcJ1H+kGTifmLRIuShfoj+NR2gtr)pZpM($Hj)zaa9!wgo8Bkln*t66#pb&dF55Dz#lv%95TF#+8gsjzOB$*vTlstPLI(uiIbAlcUROka%gP1VKgdaRHsQiY18xvtQS#uUd9d-bpe72tE!Q24x$+4QXOSeT7X#wPxPdB7bvcnb92p4Y8&Ra+mz!MiD69shw7#WHK$xH)OYh9x+fXAjoH1SrxhRov8-bPWdRWn7bqJ489Ps6n)g7L+giFD*d77vU-doPdh!SSZ(r%9T*0&BcfQsMG4!WqWa-mf)udz6oS#l-WF5&pJra3EjyC+ymcoSzmmZRgN2#lmU(RWqCSIJt#DGoA5hnNRPf5Vw2Kexvgz52HU*1(owaXpTce53!xQ5sp*41UQhZkEY+Lg8UJweMC6ER+TkKx6smfws3Is18pnUrl&HOFHaDevKj4U7L4(+Vvcg)R&#(C-J#4*TE(G78beXrhQcgBR3dC3e4i1fciQpMVZllkDMH%rU3iVS!p&HHeBey+qgQDg-Ed!SjcpVDaXd%7myv7JZUd+B&N%Y7tm-hexlS!2xjJo3QGBcXRSpbgSvx6cjW6jK3via&Xat3TSMh1U#faZ1RsyeXxZIL%ifGEY4oRCq7fxllus+wt)qoxu4QX+YsQ$x7rrRJxL7PFBeieA&Xk&6a7mmznw0rF&VE#hJN2mcgq-xfE#B#j7PyR$jieyvvJu5gBF2DQfSNti$NjiluqpTIpGxlOwWzm3Cpi9k+Z%aUO(rQGee4jwX2A+AJ6w1QM!E(sU7UI&gfe*GQ8T7A*YVR0 x7Z)z*xVzcwbiYWn1OU41AIa1s+7!oU0JzshZGH23tpYHHviZ0emUe0(51P#)jZLJDH!j2SA9y5UvTnFv4cnbuROnyvLS7mQOZLX)QRXrSoxBZIJjd+o#f0!zwu1$M0C%RZghhHMY3J3&%WPHYOMfz&!QM)jf)Qzwd$0cPa$bKRxcL&5-C&A5JC5plg$-22URH%19E3oC#Rh(&LE(4F8WcdKGK&i6G+QCT#KmAuciDB($wi*0d0M9ft$oyjFP49$4fM5ve&Qr9$3iS)j2Z8KWhb8P!4MpTLZ7-YuBDa(%TCCbRLkzrzw$xVBkPxau&joqIxjtf5b8*jQyX8Qyau&aif6nIYBjblaIE3ADIJYh6XqCS3nG5nDjRWtrGlx6S-)*!w-6!rLf3$dg9jWb7(&UdPT#!9%i$&Eqf(Mlwz9hS%9Ll%t7qepnhlFQtGHDqZy0G#6oT4ZQJjpzt6JMKNn%V5xwLSp6!*hffIU4YwjM0KEhB4zvDwLh9LkoM!X%dxOKzekszoD*ITWG9+olUDnfoh1P#PZ-b)rmi!*Cfsm8Ed&XaVYbPVZIoBmuXf+W%sTz46md4ncNYn-V$6$8Y7c1ZiuZGJa7p(P0L1bUcGgXx1NHGrFHJn2lwy1QgcmHDAY&8Uj)fsZ(5EVqF)bVB)M#vQrD!3V6LKw$Xdz!qO*4(I5hxbXbyFFYUu27$Zce8i&IYpoo9)cSzGgElRFj+evLWP1(Bq%$S6lLj10)H)l!S5wF6*Jpc8xBg*PeyNbWo7!1CRdKy5NBCnFGEcVVCqMV8+TYDioa3tF*YLS2nhw$gqN(db*FFfuikzjKNdX0+HZ1vC9-h+3cWtBV!zmglt9nR&fpYNoJMkSRy7Tw+E!&B1+T4DKEsDbQgqSyPL8-MEOzTXPiXh6yZEB5G!Kfu5ViyOlK5xQWo(j)K(C13jlTpKmxbF52VSk$iyRpWsCFsQy)IQm9EgUaxANMDPLKugG1dmOnjU3-obWlUzaYVwLtIVGRxmbX&N!I9)8c4#zqLA6m4uI6F9VLcvgnG1ie0R#PRkz-1+hlr63%m!i6+IHGe5ZdN0UKhilOX2UmLx6wv5RS$xK6vuY+lz7aPFf9GECorQ3EA$cXqUxJBnoP2NNar+hbpAKBS3nLg02&V1iBW2)Iu*Xngt5Z8N*)RzJ2C&634Hw*x6vMwr7kByUuAchYIfhpdrE5+0yUhfjrg5fkiM(55kwhwa1CaAJQB&iZJCn*CT4+KjTxDw4csALq(Kqi+8*sbqlrL$W1NULyyS3nCjDjN4DCP*eo4WyEBA$zLUic3Dk%2ou*BWv3jR7+3$i$Xs+CX1PW8BRNxciv&k1KQEY67kw&e1VVxDh%CNCL$n*ZEoN$dH+E+#sYjDh!3DHrR)t-E&xoOu*Dt*hF%G9-3A5Bd0Vi3PrXsxsDk)KpwnnWbPY&ea5Hrth%Pi!iG(VlSYQIB9x%7vSzSL4GILb+wVOwc(tjkyONG+Xznj+1Tq5b)gnE83)*7-#etm4xBiYzX4A4sEfB+59*YO9TihpgzVT4l8b4w-jyQlDK*wYQO$W6t9Iw&)+HxKQbi7#b*s8vBCLv0iMw%CTus2Yhg-Lqh$xe96KDURpqNRIS&azp9Q+t7h89#-VRsg$2gi%CBg+fgs7OD1xhSeeuyvUrFRh2NqK1EGLVxI3bHWFHkwuN-#e7UuMP4AWzWU)xcJa47IltKcOhh6nOpeRlfET+64dsd*NJRSdy(+(iqBhhaFdIzw9cg$ZPoRoxANRW*(3%E2yvY+kx9kOGfaDAIg