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Electrochemistry Lesson 7 The Standard Hydrogen Cell
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The Standard Hydrogen Half Cell
The zero point of the reduction chart is the hydrogen half-cell. E is the cell potential or voltage E0 is the standard cell potential @ 25 oC solutions are 1.0 M gases are 101 KPa
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All half reactions are compared to H2
Ag+ reacts with H2 spontaneously Eo = v Zn2+ is nonspontaneous with H2 Eo = v The voltage for any combination is the difference
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 HClO4 oxidizing
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing
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HNO3 is both H+ and NO3- Take higher one Stronger Oxidizing Agent
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing v HCl oxidizing
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing v HCl oxidizing v SO reducing
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Oxidation The reaction is reversed so the E0 = v
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing v HCl oxidizing v SO reducing v MnO4- Acid oxidizing
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing v HCl oxidizing v SO reducing v MnO4- Acid oxidizing v MnO4- Alkaline oxidizing
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Using the Reduction Potential Chart
Look on your reduction chart to find the voltage of each agent. Oxidizing agents are on the left and reducing agents are on the right. Formula Agent Type E0 ClO4- Acid oxidizing v HNO3 oxidizing v HCl oxidizing v SO reducing v MnO4- Acid oxidizing v MnO4- Alkaline oxidizing v
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Formula Agent Type E0 H2SO4 oxidizing
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H2SO4 → HSO H+ Don’t have SO42-
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Formula Agent Type E0 H2SO4 oxidizing v H2O Neutral oxidizing
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Formula Agent Type E0 H2SO4 oxidizing 0.00 v
H2O Neutral oxidizing v H2O Neutral reducing
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Formula Agent Type E0 H2SO4 oxidizing 0.00 v
H2O Neutral oxidizing v H2O Neutral reducing v Fe2+ reducing
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Formula Agent Type E0 H2SO4 oxidizing 0.00 v
H2O Neutral oxidizing v H2O Neutral reducing v Fe2+ reducing v Fe2+ oxidizing
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Formula Agent Type E0 H2SO4 oxidizing 0.00 v
H2O Neutral oxidizing v H2O Neutral reducing v Fe2+ reducing v Fe2+ oxidizing v
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Determine if the reaction below is spontaneous
Determine if the reaction below is spontaneous. Write a balanced equation for the reaction and calculate the E0. 1. MnO4- & Mn2+ Acid
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The top reaction is written forward
Reduction Oxidation The bottom reaction is reversed and the voltage is changed to negative
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Determine if the reaction below is spontaneous
Determine if the reaction below is spontaneous. Write a balanced equation for the reaction and calculate the E0. 1. MnO4- & Mn2+ Acid 2(MnO H e-→ Mn H2O) v 5(Mn H2O → MnO2(s)+ 4H e-) v 2MnO4-+16H++5Mn2++10H2O → 2Mn2++8H2O+5MnO2(s)+20H+ 2MnO Mn H2O → 5MnO2(s) H v simplify add potentials 3 2 4 0.29 v positive voltage- spontaneous
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