北京化工大学：《物理化学》课程电子教案（理科双语）Chapter 7 Electrochemistry

Electrochemistry PDF文件使用"pdfFactory Pro”试用版本创建m,fineprint.com,cn

Electrochemistry PDF 文件使用 "pdfFactory Pro" 试用版本创建 ÿwww.fineprint.com.cn

Introduction Chemical Energy Electrical Energy Chemical reactions caused by passage of electric current(reverse of voltaic process- electric current produced by chemical reactions) This chapter will discuss the conversion of chemical energy into electrical energy. Including three parts: .Electrolyte Solution .Electrochemical Cell .Electrolytic Cell and Polarization PDF文件使用"pdfFactory Pro”试用版本创建wnm,fineprint.com,cn

Introduction Chemical Energy Electrical Energy Chemical reactions caused by passage of electric current (reverse of voltaic process - electric current produced by chemical reactions) This chapter will discuss the conversion of chemical energy into electrical energy. Including three parts: •Electrolyte Solution •Electrochemical Cell •Electrolytic Cell and Polarization PDF 文件使用 "pdfFactory Pro" 试用版本创建 !www.fineprint.com.cn

Electrolyte Solution What is the conductor?The matter can flow current is called a conductor. There are two kinds of conductors. .Electronic conductor ·lonic conductor metallic conductors electrolyte electron ion Tincreasing,electric Tincreasing,electric ability decreasing ability increasing no chemical reaction existence of chemical reactions PDF文件使用"pdfFactory Pro”试用版本创建m,fineprint.com,cn

Electrolyte Solution What is the conductor? The matter can flow current is called a conductor. There are two kinds of conductors. •Electronic conductor metallic conductors electron T increasing, electric ability decreasing no chemical reaction •Ionic conductor electrolyte ion T increasing, electric ability increasing existence of chemical reactions PDF 文件使用 "pdfFactory Pro" 试用版本创建 ÿwww.fineprint.com.cn

The Electric Mechanism of Electrolyte Solution VOLTAIC CELL ELECTROLYTIC CELL Energy is released from Energy is absorbed to drive spontaneous redox reaction nonspontaneous redox reaction System does work on Surroundings(power supply) load/surroundings do work on system (cell) Load e Anode t Cathode Anode supply Cathode (reduction) (oxidation) Energy (reduction Energy rolyte Electrolyte +) (+) Oxidation half-reaction Oxidation half-reaction X—+X++日 A---A+o Reduction halt-reactian Reduction half-reaction e-+Y+-Y e-+B+→日 Overall (cell)reaction Overall (cell)reaction X+Y◆-X*+Y:△G≤0 A-+B+→A+B:△G≥0 PDF文件使用"pdfFactory Pro”试用版本创建www.fineprint.com.cn

The Electric Mechanism of Electrolyte Solution PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn

.Electrolytic Cell: Electrical Energy Chemical Energy A non-spontaneous reaction is driven by an external source of current. .Electrochemical Cell: Chemical Energy Electrical Energy It produces electricity as a result of the spontaneous reaction occurring inside it. In the electrochemical cell,chemical energy is being turned into electrical energy,while in the electrolytic cell,electrical energy is being turned into chemical energy. PDF文件使用"pdfFactory Pro”试用版本创建ww.fineprint.com,cn

•Electrolytic Cell: Electrical Energy Chemical Energy A non-spontaneous reaction is driven by an external source of current. •Electrochemical Cell: Chemical Energy Electrical Energy It produces electricity as a result of the spontaneous reaction occurring inside it. In the electrochemical cell, chemical energy is being turned into electrical energy, while in the electrolytic cell, electrical energy is being turned into chemical energy. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn

An oxidation-reduction reaction (redox)reaction involves the transfer of electrons from the reducing agent to the oxidising agent OXIDATION-is the LOSS of electrons REDUCTION-is the GAIN of electrons Zn (s)->Zn2+(aq)+2e-(aq)OXIDATION Cu2+(aq)+2e-(aq)->Cu (s)REDUCTION These represents the oxidation reduction HALF-EQUATIONS PDF文件使用"pdfFactory Pro”试用版本创建m,fineprint.com,c里

• An oxidation-reduction reaction (redox) reaction involves the transfer of electrons from the reducing agent to the oxidising agent OXIDATION - is the LOSS of electrons REDUCTION - is the GAIN of electrons Zn (s) ® Zn2+ (aq) + 2e- (aq) OXIDATION Cu2+ (aq) + 2e- (aq) ® Cu (s) REDUCTION These represents the oxidation reduction HALF-EQUATIONS PDF 文件使用 "pdfFactory Pro" 试用版本创建 ÿwww.fineprint.com.cn

Electrochemical cells An electrochemical cell consists of two electrodes,or metallic conductors,in contact with an electrolyte,an ionic conductor(which may be a solution,a liquid,or a solid). An electrode and its electrolyte comprise an electrode compartment.The two electrodes may share the same compartment. If the electrolytes are different,the two compartments may be joined by a salt bridge,which is a tube containing a concentrated electrolyte solution in agar jelly that completes the electrical circuit and enables the cell to function. PDF文件使用"pdfFactory Pro”试用版本创建耀m,fineprint.com,cn

Electrochemical cells An electrochemical cell consists of two electrodes, or metallic conductors, in contact with an electrolyte, an ionic conductor (which may be a solution, a liquid, or a solid). An electrode and its electrolyte comprise an electrode compartment. The two electrodes may share the same compartment. If the electrolytes are different, the two compartments may be joined by a salt bridge, which is a tube containing a concentrated electrolyte solution in agar jelly that completes the electrical circuit and enables the cell to function. PDF 文件使用 "pdfFactory Pro" 试用版本创建 耀www.fineprint.com.cn

Reactions at electrodes The reduction and oxidation processes responsible for the overall reaction in a cell are separated in space: oxidation takes place in one electrode compartment and reduction takes place in the other compartment.As the reaction proceeds,the electrons released in the oxidation Red1→Ox+ze at one electrode travel through the external circuit and re-enter the cell through the other electrode.There they bring about reduction: Ox2+ze→Red So,the electric mechanism of electrolyte solution includes the reactions of electrodes and the ions movements in the solution. PDF文件使用"pdfFactory Pro”试用版本创建fww.fineprint.com.cn

Reactions at electrodes The reduction and oxidation processes responsible for the overall reaction in a cell are separated in space: oxidation takes place in one electrode compartment and reduction takes place in the other compartment. As the reaction proceeds, the electrons released in the oxidation Red1 Ox1+ z e￾at one electrode travel through the external circuit and re-enter the cell through the other electrode. There they bring about reduction: Ox2 + z e- Red2 So, the electric mechanism of electrolyte solution includes the reactions of electrodes and the ions movements in the solution. PDF 文件使用 "pdfFactory Pro" 试用版本创建 fwww.fineprint.com.cn

The Naming of Electrodes According to reduction and oxidation, Cathode---the electrode at which reduction occurs is called the cathode. Anode---the electrode at which oxidation occurs is called the anode. According to cell potential, Positive electrode---the electrode which has high potential is called positive electrode. Negative electrode---the electrode which has low potential is called negative electrode. PDF文件使用"pdfFactory Pro”试用版本创建fmm,fineprint.com,cn

The Naming of Electrodes According to reduction and oxidation, Cathode--- the electrode at which reduction occurs is called the cathode. Anode--- the electrode at which oxidation occurs is called the anode. According to cell potential, Positive electrode--- the electrode which has high potential is called positive electrode. Negative electrode---the electrode which has low potential is called negative electrode. PDF 文件使用 "pdfFactory Pro" 试用版本创建 fwww.fineprint.com.cn

.Electrolytic Cell:positive electrode anode negative electrode cathode .Electrochemical Cell:positive electrode cathode negative electrode anode Anode Cathode Process: Oxidation Reduction Potential:Low(-) High(+)for electrochemical cell High(+) Low(-)for electrolytic cell PDF文件使用"pdfFactory Pro'”试用版本创建wm,fineprint.com,cn

•Electrolytic Cell: positive electrode = anode negative electrode = cathode •Electrochemical Cell: positive electrode = cathode negative electrode = anode Anode Cathode Process: Oxidation Reduction Potential: Low(-) High(+) for electrochemical cell High(+) Low(-) for electrolytic cell PDF 文件使用 "pdfFactory Pro" 试用版本创建 ÿwww.fineprint.com.cn