Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...
Transcript of Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...
![Page 1: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/1.jpg)
Potenciometría
![Page 2: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/2.jpg)
Celda galvánica
![Page 3: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/3.jpg)
Electrodos
![Page 4: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/4.jpg)
Electrodo de hidrógeno
![Page 5: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/5.jpg)
Electrodo de calomelanos
![Page 6: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/6.jpg)
Electrodo de Ag/AgCl
![Page 7: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/7.jpg)
Electrodos de 1ª clase
![Page 8: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/8.jpg)
Electrodos de 2ª clase
![Page 9: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/9.jpg)
Electrodos de 3ª clase
![Page 10: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/10.jpg)
Electrodos inertes
![Page 11: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/11.jpg)
Electrodos selectivos
![Page 12: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/12.jpg)
Potencial de membrana
KCl 0.1 M KCl 0.01 M
R R
R
R-K
R
R-K
K+ 0.1
Cl- 0.1
K+ 0.01
Cl- 0.01
K+ (0.1-x) K+(0.01+x)
Cl- 0.1 Cl- 0.01
![Page 13: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/13.jpg)
Electrodo de vidrio
![Page 14: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/14.jpg)
Medida del pH
![Page 15: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/15.jpg)
Medida del pH
![Page 16: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/16.jpg)
Medida del pH
![Page 17: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/17.jpg)
Membrana de vidrio
![Page 18: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/18.jpg)
Hidratación de la membrana de vidrio
![Page 19: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/19.jpg)
Potencial a través de la membrana
![Page 20: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/20.jpg)
Coeficiente de selectividad
![Page 21: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/21.jpg)
Electrodos de membrana cristalina
![Page 22: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/22.jpg)
Electrodo de fluoruroelectrodo de referencia interno
disolución de NaF 0.1 M + NaCl 0.1 M
tubo de plástico
.
monocristal de LaF3(con EuF2)
![Page 23: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/23.jpg)
Interferencias
Analito MembranaMargen de
concentraciones (M)
Interferencias(algunas)
F–
Cl–Br–
I–
CN–
SCN–
Ag+/S2–
Cu2+
Cd2+
Pb2+
LaF3AgClAgBrAgIAgI
AgSCNAgS2
AgS2(CuS)AgS2(CdS)AgS2(PbS)
sat. — 10–6
1 — 5x10–5
1 — 5x10–6
1 — 5x10–8
10–2 — 10–6
1 — 5x10–6
1 — 10–7
10–1 — 10–8
10–1 — 10–7
10–1 — 10–6
OH–
S2–, CN–, I–, Br–
S2–, CN–, I–
S2–
S2–, I–
S2–, I–, CN–, Br–
Hg2+ (<10–7)Ag+, Hg2+
Ag+, Hg2+, Cu2+
Ag+, Hg2+, Cu2+
![Page 24: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/24.jpg)
Electrodos de membrana líquida
![Page 25: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/25.jpg)
Electrodos de membrana líquida: mecanismo
![Page 26: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/26.jpg)
Sondas sensibles a gases
![Page 27: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/27.jpg)
Biomembranas
ureasa inmovilizada
membrana
electrodo de vidrio sensible al NH4+
H2N-CO-NH2 + 2 H2O + H+ ------ HCO3- + 2 NH4
+ureasa
![Page 28: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/28.jpg)
Ventajas e inconvenientes
VENTAJAS:* Amplio intervalo lineal* Disoluciones turbias o coloreadas* Medidas razonablemente rápidas* Instrumentación barata y portátil* Método no destructivo
INCONVENIENTES:* Interferencias numerosas* Calibración frecuente* No para ultratrazas
![Page 29: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/29.jpg)
Valoraciones potenciométricas
![Page 30: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/30.jpg)
Valoraciones redox
i
Eref.
Fe2+
Fe3+
x=0
x=0.5
H O2 O2
Ean.x=1Ecat.
Ce4+Ce3+
1/2E Ce /Ce4+ 3+E Fe /Fe3+ 2+
1/2
Fe3+
Fe2+
H O2H2
+iε
–iε
x>1
E
Ce3+ Ce4+
E
x1
E
x1
Fe /Fe3+ 2+A
B
Ce /Ce4+ 3+
a b
a b
∆E
1 x
![Page 31: Potenciometría · Potenciometría Author: CLAUDIO Created Date: 11/27/2008 1:00:18 PM ...](https://reader034.fdocumento.com/reader034/viewer/2022050216/5f6257cae3a14a57451af2a9/html5/thumbnails/31.jpg)
Detección del punto final