教育专题：有关pH计算

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,*,一,、,pH,的测定方法,方法一：,pH,试纸,用法,：用玻璃棒蘸溶液，点在,pH,试纸中央，,半分钟内,与比色卡比色,标准比色卡中的数据都是整数,注意：,不能用水润湿,要放在玻璃片（或表面皿）上,不是将试纸伸到溶液中,广泛,pH,试纸只能读出整数,方法二：用,pH,计测定,第二节,（第二课时）,有关,pH,的计算,pH=-lg,c,(H,+,),二、,pH,的计算,酸性溶液，直接求,pH,碱性溶液，先求,c(OH,-,),，再求,c(H,+,)pH,混合溶液，先判断酸碱性，再根据以上方法求,无限稀释,接近,7,pH,计算,强酸的稀释,例题：在,25,时，将,1mL pH,值等于,3,的硫酸溶液稀释到,100 mL,，溶液的,pH,值等于多少？,解：,pH=-lgH,+,=-lg 1.0 10,-5,=5,关键：抓住氢离子进行计算！,C(H,+,)=1.0 10,-5,mol/L,溶液的稀释,稀释后,PH,pH=3,的稀盐酸加水稀释,100,倍,pH=2,的稀硫酸加水稀释,100,倍,5,4,约为,7,pH=5,的稀盐酸加水稀释,1000,倍,pH,计算,强碱的稀释,例题：在,25,时，,pH,等于,12,的强碱溶液稀释到原来的,100,倍，,pH,等于多少？,解：,稀释前：,c(OH,-,),=,pH=-lgc(H,+,),关键：抓住氢氧根离子进行计算！,稀释后：,c(OH,-,),=,C(H,+,),=,=10,=1 10,-2,mol/L,=1 10,-4,mol/L,=,=1,10,-10,mol/L,溶液稀释的,pH,计算,溶液的稀释,稀释后所得溶液的,P,H,pH=11,的,NaOH,溶液加水稀释,100,倍,pH=12,的,Ba(OH),2,溶液加水稀释,100,倍,9,10,约为,7,pH=9,的,NaOH,溶液加水稀释,1000,倍,pH,计算,3,弱酸、弱碱的稀释,3,pH,4,11,pH,12,例题、,pH=3,的,HAc,加水稀释到原来,10,倍，溶液的,pH,值范围,_,pH=12,氨水加水稀释到原来,10,倍，溶液的,pH,值范围,_,pH,计算,4,强酸与强酸混合,例题：在,25,时，,pH,值等于,1,的盐酸溶液和,pH,值等于,4,的硫酸溶液等体积混合,pH,值等于多少？,解：,pH=-lgc(H,+,),=-lg,（,110,1,+110,4,）,/,（,1+1,）,=-lg510,2,=2-lg5,=1.3.,关键：抓住,氢离子,进行计算！,pH=2,的盐酸和,pH=4,的盐酸溶液等体积混合后，所得溶液的,pH,。,pH=2,的盐酸和,pH=5,的硫酸溶液等体积混合后，所得溶液的,pH,。,两种,pH,值不同的强酸等体积混合时,pH2,时，,pH,混,=pH,小,+0.3,pH=3,的盐酸和,pH=4,的硫酸溶液体积比按,11,混合后溶液的,pH,。,pH=1,时，,pH,混,=pH,小,+0.26,2.3,2.3,3.26,练习,pH,计算,5,强碱与强碱混合,解：,=-lg2+11,=10.7,例题：在,25,时，,pH,值等于,9,和,pH,值等于,11,的两种氢氧化钠溶液等体积混合,pH,值等于多少？,C(OH,)=,（,1 10,5,+110,3,）,/(1+1),C(H,+,)=10,-14,/OH,-,pH=-lg10,-14,/(10,-3,/2),关键：抓住,氢氧根离子,进行计算！,练习,1,、,pH=13,的,Ba(OH),2,溶液与,pH=10,的,NaOH,溶液体积比按,11,混合后的,pH,值,_,。,两种,pH,值不同的强碱等体积混合时,pH2,时，,pH,混,=pH,大,-0.3,pH=1,时，,pH,混,=pH,大,-0.26,2,、,pH=13,的,NaOH,溶液与,pH=12,的,NaOH,溶液体积比按,11,混合后的,pH,值,_,。,12.74,12.7,pH,计算,6,强酸与强碱混合,例题：在,25,时，,100ml 0.6mol/L,的盐酸与等体积,0.4mol/L,的氢氧化钠溶液混合后,溶液的,pH,值等于多少？,解：,NaOH+HCl=NaCl+H,2,O,0.06,0.04,pH=-lgc(H,+,),=-lg0.02/,（,0.1+0.1,）,=-lg10,1,=1,关键：酸过量抓住,氢离子,进行计算！,pH,计算,6,强酸与强碱混合,例题：在,25,时，,100mlO.4mol/L,的盐酸与等体积,0.6mol/L,的,氢氧化钠溶液混合后,溶液的,pH,值等于多少？,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,关键：碱过量抓住,氢氧根离子,进行计算！,0.1(0.6-0.4)/0.2,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,解：,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,pH=-lg10,-13,=,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,13,NaOH+HCl=NaCl+H,2,O,0.04,0.06,13,0.04,0.06,13,0.04,0.06,13,0.04,0.06,13,C(OH,)=0.1(0.6-0.4)/0.2,C(H,+,)=10,-14,/c(OH,)=10,-14,/0.1,pH,计算,7,酸碱混合,规律,(1)pH,为,12,的,NaOH,溶液和,pH,为,2,的盐酸等体积混合，,溶液呈,_,中,_ _,性。,(2)pH,为,11,的,NaOH,溶液和,pH,为,2,的盐酸等体积混合，,溶液呈,_,酸,_ _,性,(3)pH,为,12,的,NaOH,溶液和,pH,为,3,的盐酸等体积混合，,溶液呈,_,碱,_,性,酸,碱,大于等于,7,小于等于,7,练习：,（,1,）,pH,为,12,的,NaOH,溶液和,pH,为,2,的醋酸溶液等体积相混合，则混合液呈,_,性,（,2,）,pH,为,12,的氨水和,pH,为,2,的盐酸等体积相混合，则混合液呈,_,性,（,3,）,pH,为,2,的盐酸和,pH,为,12,的某碱等体积相混合，则混合液,PH_,（,4,）,pH,为,12,的,NaOH,溶液和,pH,为,2,的某酸溶液等体积相混合，则混合液,PH,_,1,、某酸溶液的,pH,为,2,，某碱溶液的,pH,为,12,，两者等体积相混合后，有关,pH,值的变化正确的是（）,A,、大于,7 B,、小于,7,C,、等于,7 D,、三种都有可能,D,练习：,加水体积,pH,HB,HA,2,、酸,HA,、,HB,两溶液的,pH,值为,3,，且体积相同，加水稀释两溶液，,pH,值与加入水的体积关系如图所示，则两者酸性较强的是（）,HB,3,、同体积的,pH,为,3,的盐酸、硫酸、醋酸和硝酸四种溶液，分别加入足量的锌粉，叙述正确的是（）,A,、,硫酸溶液中放出的氢气的量最多,B,、,醋酸溶液中放出的氢气的量最多,C,、,盐酸和硝酸中放出的氢气的量相等,D,、盐酸比硝酸放出的氢气的量多,BD,溶液的,pH,值,正误判断,1,、一定条件下,pH,值越大，溶液的酸性越强。,2,、用,pH,值表示任何溶液的酸碱性都很方便。,3,、强酸溶液的,pH,值一定大。,4,、,pH,值等于,6,是一个弱酸体系。,5,、,pH,值有可能等于负值。,6,、,pH,值相同的强酸和弱酸中,H,+,物质的量的浓度相同,。,7.PH=9,的,NaOH,溶液加水稀释,1000,倍后,pH,值约为,6,