Chapter 18 Electrochemistry Lesson 18.1 Galvanic Cells Summary We encounter electrochemical cells in our everyday lives from the disposable AA batteries in our remote controls to the lithium-ion batteries in our iPhones. There are two types of electrochemical cells: Galvanic Cells or Voltalic Cells Electrolytic cells Galvanic cellis a device that Converts The Chemical Energy (derived from spontaneous redox reactions) to Electric Energy ( will be discussed in lesson 18.7) How can we harness this energy ? The key is by separation the 2 half reactions into 2 different cells connected by a wire ,the current produced in the wire by the electron flow can then be directed through a device like electric motor to produce useful work https://www.youtube.com/watch?v=C26pH8kC_Wk 2e- Zn Cu Zn Cu Zn Cu Zn Cu Zn Cu Zn2+ Zn2+ SO42- Cu2+ SO42- 2e- Zn Cu Zn Cu Zn Cu Zn Zn2+ Cu Zn Cu Zn2+ SO42- Cu2+ Cu SO42- Oxidation Reduction Anode RED-CAT AN-OX Due to the gaining of electrons Due to the losing of electrons Zn Cu Zn Cu Zn Cu Zn Cathode Zn2+ Cu Zn Cu Zn2+ SO42- Cu2+ Cu SO42- RED-CAT AN-OX 2e- Zn Cu Zn Cu Salt Bridge Zn Zn Zn Amount of Zn2+ INCREASES Cu Zn2+ Cu Zn2+ Zn2+ Zn2+ Cu SO42- Amount of Cu2+ DECREASES Cu2+ Cu Cu Cu SO42- Cu 1- Zinc (s) Metal Loses electrons and form 𝒁𝒏𝟐+ ions in the beaker 2-electrons pass through the wire to the reduction half reaction cell 3-Cupper ions from the beaker accepts the electrons and form copper atoms(s) 4- The salt bridge maintain neutrality of the solutions by adding 𝑪𝒍− to the oxidation half Cell and 𝑵𝒂+ to the reduction half cell 5-The mass of Zinc Metal decreases and the Mass of the copper Metal increases Definitions : Electrodes : Solid Electric Conductors Cathode : (+ve Terminal ) Electrons Enter the cell through the Cathode (Reduction Occur) Anode (-ve Terminal ) Electrons Leaves the cell through the Anode (Oxidation Occur ) Cell Potential : A galvanic cell consists of an oxidizing agent in one compartment that pulls electrons from the reducing agent in the other compartment .The pull ,or driving force ,on the electrons is called the cell potential (E cell) or the electron motive force (EMF) of the cell .The unit of electric potential is the volt (abbreviation V ) Cell potential can be measured by Digital Voltmeters
