配置ph为5的缓冲溶液，应选择的缓冲系是 A磷酸-磷酸二氢钠 pka等于2.12 pH值为5.5的缓冲溶液怎么配，如果用磷酸二氢钾和磷酸氢钠，...
\u9009\u62e9\u9898\uff1a\u914d\u5236PH=5\u7684\u7f13\u51b2\u6eb6\u6db2\uff0c\u53ef\u9009\u62e9\u7684\u7f13\u51b2\u5bf9\u6709\u54ea\u4e9b?B\u3002
A\u548cD\u7684\u6eb6\u6db2\u914d\u51fa\u6765\u662f\u78b1\u6027\u7684\u3002C\u7684\u7f13\u51b2\u6eb6\u6db2\u504f\u9178\u6027\u592a\u591a\u4e86\uff0c\u4e00\u822c\u4e3a\u4e86\u4fdd\u8bc1\u8f83\u5927\u7684\u7f13\u51b2\u5bb9\u91cf\uff0c\u7f13\u51b2\u6eb6\u6db2\u7684pH\u5e94\u8be5\u5728pKa\u4e0a\u4e0b\u5404\u4e00\u4e2apH\u5355\u4f4d\u4e4b\u5185\u3002\u4e5f\u5c31\u662f\u8bf4\u5982\u679c\u8981\u914d\u7684\u7f13\u51b2\u6eb6\u6db2\u7684pH\u57282.74-4.74\u4e4b\u95f4\u7684\u8bdd\u5c31\u53ef\u4ee5\u7528C\u4e86\u3002
\u6269\u5c55\u8d44\u6599\uff1a
\u4e00\u822c\u8fc7\u7a0b\u662f\uff1a
1\u3001\u9009\u62e9\u4e00\u5b9a\u7684\u7f13\u51b2\u5bf9
\u914d\u5236PH=5\u7684\u7f13\u51b2\u6eb6\u6db2\uff0c\u9009\u7528 HAc - Ac- \u7f13\u51b2\u5bf9\u6bd4\u8f83\u597d
\u539f\u56e0\u662f\uff1a
\u9009\u53d6\u7f13\u51b2\u6eb6\u6db2\u7684pKa\u4e0e\u6b32\u914d\u5236\u7684\u6eb6\u6db2\u7684pH\u63a5\u8fd1\uff0c\u6bd4\u5982\uff1a
pKa(HAc) = 4.76 ,\u4e0epH = 5\u8f83\u63a5\u8fd1
2\u3001\u8c03\u8282\u7f13\u51b2\u5bf9\u7684\u6d53\u5ea6\u6bd4
pH = pKa - lg [HAc] / [Ac-]
5 = 4.76 - lg [HAc] / [Ac-]
[HAc] / [Ac-] = 0.575
\u5373HAc\u548cNaAc\u7684\u7269\u8d28\u7684\u91cf\u6d53\u5ea6\u6bd4\u4e3a0.575\u65f6\u5373\u8fbe\u5230\u8981\u6c42
\u53c2\u8003\u8d44\u6599\u6765\u6e90\uff1a\u767e\u5ea6\u767e\u79d1-\u7f13\u51b2\u5242
\u201c\u5982\u679c\u7528\u78f7\u9178\u4e8c\u6c22\u94be\u548c\u78f7\u9178\u6c22\u94a0\uff0c\u6216\u8005\u7528\u78f7\u9178\u6c22\u4e8c\u94be\u548c\u78f7\u9178\u4e8c\u6c22\u94be\u201d\uff0c\u662f\u914d\u5236\u4e0d\u51fapH\u503c\u4e3a5.5\u7684\u7f13\u51b2\u6eb6\u6db2\u7684\u3002
\u914d\u5236\u7f13\u51b2\u6eb6\u6db2\u7684\u539f\u5219\u662fPH=PKa\u00b11
\u800c\u78f7\u9178\u4e8c\u6c22\u76d0\u7684PKa2=7.2\u3002
\u663e\u7136PH=5.5\u503c\u4e0d\u57287.2\u00b11\u8303\u56f4\u5185\u3002
醋酸的PKa=4.75，配置PH=5
那c盐=1.78c酸，即可
而磷酸-磷酸二氢钠，0.1molL-磷酸二氢钠的ph值都小于5，配不到5.
绛旓細pH=pKa+lg[c(纰憋級/c(閰革級] 5=4.74+lg[0.05/c] c= 0.275mol/L 鎵鍙栫殑鍘熷婧舵恫鐨勬祿搴﹀簲璇ュ姞鍊 0.275mol/L*2=0.550mol/L 搴斿啀鍙125mL 0.550mol/L鐨凥AC婧舵恫
绛旓細缂撳啿婧舵恫鐨勬湁鏁堢紦鍐茶寖鍥鐨凱H鍊间负PKa卤1涔嬮棿銆傚墠鍥撅紝閫夋嫨B鏄纭殑銆傚洜涓篕b=1.8脳10^-5 锛孭Kb=4.75 PKa=14-4.75=9.25 ,PH=9.2鍦9.25卤1涔嬮棿銆傚悗鍥锛屽簲璇ラ夋嫨C,Ka=1.76脳10^-5 锛孭Ka=4.75 ,PH=5 ,鍦4.75卤1涔嬮棿銆
绛旓細PH=5,c(H+)=10^-5 c(H+)=Ka*[c(寮遍吀)/c(寮遍吀鐩)]10锛撅紞5锛1.76锛10锛撅紞5*[c(寮遍吀)/c(寮遍吀鐩)][c(寮遍吀鐩)/c(寮遍吀)]锛1.76 c(寮遍吀鐩)锛漜(寮遍吀)锛1.76 鍦500ml1.0mol/L鐨凥Ac婧舵恫涓,閱嬮吀鐨勭墿璐ㄧ殑閲忥紳0.5锛1锛0.5鎽╁皵 閱嬮吀閽犵殑鐗╄川鐨勯噺锛0.5锛1.76/(1+1.76)=...
绛旓細PH=PKa-lg[HAc]/[Ac-]5=4.75-lg[HAc]/[Ac-]lg[HAc]/[Ac-]=-0.25 [HAc]/[Ac-]=0.56/1 鍗冲彧瑕丠Ac涓嶯aAc鐨勭墿璐ㄧ殑閲忔瘮涓0.56/1锛屽氨鍙互閰嶅埗鍑篜H=5鐨勭紦鍐叉憾娑銆傚彲浠ョ敤鍐伴唻閰稿拰姘㈡哀鍖栭挔鏉ラ厤鍒躲傚鏋滄憾娑茬殑娴撳害涓1mol/L锛岄厤鍒舵憾娑茬殑浣撶Н涓1000姣崌锛岄偅涔 闇瑕佸啺閱嬮吀鐨勮川閲鏄60鍏嬶紱...
绛旓細鍙嶅簲鍚庢憾娑叉垚浠斤細NaAc 銆丠Ac 鏄剧劧鏄紦鍐叉憾娑 HAc <=>Ac + H + Ka(HAc)=[H+]*[Ac-]/[HAc]=绾= [H+]*c(Ac-锛/c(HAc)=绾= [H+]*n(Ac-)/n(HAc)1.75*10^-5=10^-5 *n(Ac-)/n(HAc)鍒: n(Ac-)/n(HAc)=1.75 鑰: n(Ac-) + n(HAc)=500ml*0.5mol/l=...
绛旓細涓ф煚妾吀閾婧舵恫鐨勯厤鍒讹細绉500g鏌犳閰告憾瑙ｄ簬25%姘ㄦ按婧舵恫(绾500ml),涓拰(鍛堥吀鎬у姞姘ㄦ按,鍛堢⒈鎬у姞鎷ф閰)鑷充腑鎬у弽搴斾负姝(鐢╬H璁℃祴瀹).鍔犲叆钂搁姘村畾瀹硅嚦1L,杩囨护澶囩敤.銆
绛旓細缂撳啿婧舵恫鐨閰嶇疆绛旀濡備笅锛1锛閫夋嫨閫傚綋鐨勭紦鍐插锛屼娇閰嶅埗婧舵恫鐨PH鍊煎湪鎵閫夋嫨鐨勭紦鍐插鐨勭紦鍐茶寖鍥村唴銆傝繖涓寖鍥村ぇ绾﹀湪PKa1涔嬪唴銆備緥濡侶OAc-OAc-缂撳啿瀵圭殑鑼冨洿鏄3.7-5.6锛岃閰嶅埗PH浠3.7-5.6涔嬮棿鐨勭紦鍐叉憾娑鍙閫夌敤杩欎竴缂撳啿瀵广2锛庣紦鍐插涓綔涓哄叡杞吀鐨凱Ka锛屽簲灏介噺鎺ヨ繎浜庨厤鍒舵憾娑茬殑PH鍊笺備緥濡傦紝瑕侀厤鍒PH涓...
绛旓細鍙鎴戜滑鐭ラ亾瑕侀厤鍒鐨勭紦鍐叉恫鐨刾H锛缁忔煡琛ㄤ究鍙绠楀嚭鎵鐢ㄧ紦鍐插墏鐨勬瘮渚嬪拰鐢ㄩ噺銆備緥濡傞厤鍒500nmpH5.8娴撳害涓0.1M纾烽吀缂撳啿娑层傜粡鏌ヨ〃鐭H5.8娴撳害涓0.2M Na2HPO48.0姣崌锛岃0.2M Na2HPO492.0姣崌銆備緷姝ゅ彲鎺ㄨ鍑洪厤鍒100ml0.1M鐨勭７閰哥紦鍐叉恫闇瑕0.1M Na2HPO48.0姣崌锛岃0.1M Na2HPO4闇瑕92.0姣崌銆傝...
绛旓細1)宸茬煡锛氶唻閰哥殑PKa=4.74,閱嬮吀閽犵殑鎽╁皵璐ㄩ噺=82.03g/mol ,鍐颁箼閰哥殑娴撳害=17mol/L,500ml=0.5L 2锛夎绠缂撳啿婧舵恫涓唻閰搁挔鍜岄唻閰哥殑娴撳害姣斿硷細PH=PKa+lg[AC-]/[HAC]5.00=4.74+lg[AC-]/[HAC][AC-]/[HAC]=1.82 3)璁＄畻閱嬮吀閽犲拰閱嬮吀鐨勬祿搴︼細鍋囪閱嬮吀閽犵殑娴撳害涓篊,鍒欓唻閰哥殑娴撳害涓1-C C/(...
绛旓細PH=PKa-lg[HAc]/[Ac-]5=4.76-lg[HAc]/[Ac-]lg[HAc]/[Ac-]=-0.24 [HAc]/[Ac-]=0.575 闇瑕6mol/L閱嬮吀鐨勪綋绉1000脳0.575脳0.125/6=12姣崌
