122:
121:
221:
is used as an indicator; the end-point is marked by the green suspension turning pink. Prior to the end-point of the titration, chloride ions remain in excess. They adsorb on the AgCl surface, imparting a negative charge to the particles. Past the equivalence point, excess silver(I) ions adsorb on
193:
or AgHCrO4 at low pH, reducing the concentration of chromate ions, and delaying the formation of the precipitate. Carbonates and phosphates precipitate with silver, and need to be absent to prevent inaccurate results.
205:. Calcium acetate "fixes" free chlorine, precipitates carbonates, and neutralizes the resultant solution. Ferric acetate removes phosphates. All chlorides are dissolved out of the residue, and titrated.
222:
the AgCl surface, imparting a positive charge. Anionic dyes such as dichlorofluorescein are attracted to the particles, and undergo a colour change upon adsorption, representing the end-point.
74:, involves the addition of excess silver nitrate to the analyte; the silver chloride is filtered, and the remaining silver nitrate is titrated against
129:
is added as indicator in an
Erlenmeyer flask and the end of the reaction is determined by the slight red color given by the silver chromate.
322:
197:
The Mohr method may be adapted to determine the total chlorine content of a sample by igniting the sample with
343:
238:
anions, giving a sharper end-point than dichlorofluorescein. It is not suitable for titrating against
79:
83:
75:
17:
8:
218:
134:
348:
138:
126:
40:
of known concentration. Chloride ions react with silver(I) ions to give the insoluble
318:
295:
214:
178:
198:
142:
41:
284:"Adaptation of the Mohr Volumetric Method to General Determinations of Chlorine"
202:
67:
37:
337:
255:
71:
36:
present in a sample. The sample solution is titrated against a solution of
235:
299:
260:
25:
283:
243:
239:
33:
227:
317:(6th ed.). San Francisco: W.H. Freeman. pp. 142–143.
231:
29:
223:
226:(tetrabromofluorescein) is suitable for titrating against
32:(I) ion. Typically, it is used to determine the amount of
312:
242:anions because it binds to AgCl more strongly than
125:Determining chlorides in water by the Mohr method.
335:
177:The solution needs to be near neutral, because
281:
181:forms at high pH, while the chromate forms Ag
120:
277:
275:
336:
288:Industrial & Engineering Chemistry
145:after all chloride ions have reacted:
82:as an indicator which forms blood-red
272:
13:
213:In the Fajans method, named after
70:, the Volhard method, named after
14:
360:
133:In the Mohr method, named after
89:Ag (aq) + SCN (aq) → AgSCN (s) (
313:Harris, Daniel Charles (2003).
315:Quantitative chemical analysis
306:
48:Ag (aq) + Cl (aq) → AgCl (s) (
1:
266:
141:is an indicator, giving red
7:
249:
10:
365:
61:
56:
208:
116:
112:(aq) + SCN (aq)→ + OH
80:ferric ammonium sulfate
282:Yoder, Lester (1919).
130:
124:
344:Analytical chemistry
76:ammonium thiocyanate
18:analytical chemistry
300:10.1021/ie50116a013
219:dichlorofluorescein
135:Karl Friedrich Mohr
139:potassium chromate
131:
127:Potassium chromate
85:at the end point:
356:
329:
328:
310:
304:
303:
279:
215:Kazimierz Fajans
179:silver hydroxide
157:
156:
111:
110:
364:
363:
359:
358:
357:
355:
354:
353:
334:
333:
332:
325:
311:
307:
280:
273:
269:
252:
211:
192:
188:
184:
172:
165:
161:
155:
152:
151:
150:
143:silver chromate
119:
109:
106:
105:
104:
102:
95:
64:
59:
42:silver chloride
12:
11:
5:
362:
352:
351:
346:
331:
330:
323:
305:
270:
268:
265:
264:
263:
258:
251:
248:
210:
207:
203:ferric acetate
190:
186:
182:
175:
174:
170:
163:
159:
153:
149:2Ag (aq) + CrO
118:
115:
114:
113:
107:
100:
97:
93:
68:back titration
66:An example of
63:
60:
58:
55:
54:
53:
38:silver nitrate
28:involving the
9:
6:
4:
3:
2:
361:
350:
347:
345:
342:
341:
339:
326:
324:0-7167-4464-3
320:
316:
309:
301:
297:
293:
289:
285:
278:
276:
271:
262:
259:
257:
256:Silver halide
254:
253:
247:
245:
241:
237:
233:
229:
225:
220:
216:
206:
204:
200:
195:
180:
169:
148:
147:
146:
144:
140:
136:
128:
123:
98:
92:
88:
87:
86:
84:
81:
77:
73:
72:Jacob Volhard
69:
51:
47:
46:
45:
43:
39:
35:
31:
27:
24:is a type of
23:
19:
314:
308:
291:
287:
217:, typically
212:
196:
176:
173:= 1.1 × 10)
167:
132:
96:= 1.16 × 10)
90:
65:
52:= 5.88 × 10)
49:
22:argentometry
21:
15:
236:thiocyanate
338:Categories
294:(8): 755.
267:References
349:Titration
261:Titration
158:(aq) → Ag
99:Fe(OH)(OH
26:titration
250:See also
244:chloride
240:chloride
34:chloride
228:bromide
201:, then
199:calcium
78:, with
62:Volhard
57:Methods
321:
246:does.
234:, and
232:iodide
209:Fajans
30:silver
224:Eosin
166:(s) (
319:ISBN
117:Mohr
296:doi
162:CrO
16:In
340::
292:11
290:.
286:.
274:^
230:,
185:Cr
171:sp
137:,
94:sp
44::
20:,
327:.
302:.
298::
191:7
189:O
187:2
183:2
168:K
164:4
160:2
154:4
108:5
103:)
101:2
91:K
50:K
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