Created by Natasha Gidluck
over 6 years ago
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Question | Answer |
Historical Definitions | Reduction: The loss of mass when a metal is refined from its ore Oxidation: reacting a substance with oxygen (often a metal) |
Modern Definitions | Reduction: The gain or partial gain of electrons Oxidation: The loss or partial loss of electrons |
Half-Reactions | Show how stable substances gain or lose electrons to form their respective charged ions. Can be a reduction half-reaction or an oxidation half-reaction |
Net Ionic Equations | Two half-reactions combined to form a singular equation. Will always be a reduction half-reaction mixed with an oxidation half-reaction |
Electronegativity | Can play an important role in the ways that electrons are transferred or shared |
Redox Reactions | Must have a reducing agent and an oxidizing agent One substance is reduced and one substance is oxidized The net reduction must equal the net oxidation |
Oxidizing Agents | Substances that cause oxidation The substance that is being reduced is the OA because it causes the other to be oxidized |
Reducing Agents | Substances that cause reduction The substance that is being oxidized is the RA because it causes the other to be reduced |
Redox Table | Shows the half-reactions of substances and combinations of substances Shows the relative strengths of OAs and RAs |
Spontaneous Reaction | When a reaction occurs naturally and products are formed. The strongest oxidizing agent is on the left side of the equation |
Non-Spontaneous Reaction | When a reaction does not occurs naturally and products are not formed. The strongest oxidizing agent is on the right side of the equation |
Oxidation Numbers | Numbers assigned to all types of substances as if they were an ionic charge. The rules are: Elements are 0 Oxygen is (-2) unless it is peroxide or w/ F Hydrogen is (+1) unless it is a hydride The oxidation # for an ion is the same as its charge The oxidation number for a compound is either 0 or its charge |
Types of Redox Questions | Constructing a Redox Table Predicting a Redox Reaction Balancing Redox Equations (Oxidation numbers or Half-Reactions) Titration Questions/Redox Stoichiometry |
Electrochemical Cell | Contains solid electrodes dipping into an electrolyte solution, is composed of two half-reactions (one at each electrode), and allows for a load to use energy (using the flow of electrons) |
Electrochemical Cells Must Include | Oxidation Half-Reaction Reduction Half-Reaction Net Ionic Equation Voltage of the Cell. Line Notation Labelled Anode Labelled Cathode Labelled Electrolyte Direction of Electron Flow Ion Movement |
Anode | A solid electrode that serves as the location of oxidation. Anions migrate toward the anode. Electrons are produced. |
Cathode | A solid electrode that serves as the location of reduction. Cations migrate toward the cathode. Electrons are consumed. |
Types of Electrochemical Cells | Voltaic and Electrolytic |
Voltaic Cells | Are always a spontaneous reaction, even if it is normally non-spontaneous. Always goes from the anode to the cathode. Takes place in two separate containers that are connected with a salt-bridge or porous boundary. Converts chemical energy to electrical energy. Has a positive cell potential. |
Electrolytic Cells | Always a non-spontaneous reaction, even if it is normally spontaneous. Always goes from the anode to the cathode. Takes place in one container. Converts electrical energy to chemical energy. Has a negative cell potential. |
Dry Cells | A carbon cell with a paste electrolyte and carbon rod. A normal battery would be a dry cell. |
Alkaline Cells | Batteries that improve on long term efficiency compared to a dry cell |
Button Cells | Small circular cells that have the cathode on the bottom that is either mercury or silver oxide. |
Lead Acid Battery | Multiple cells set up in a series with a lead plate separated with porous material |
Nicads | Nickel cadmium cells that are not efficient because they develop a memory as the reverse reaction becomes harder to do. |
Fuel Cells | Highly efficient fossil fuel cells that make a continuous energy input and output |
Primary Cells | Non-reversible reactions which are used and the discarded. |
Secondary Cells | Reversible reactions that store energy and are able to recharge after energy is depleted. |
Net Voltage | The sum of reduction and oxidation potential Listed in the data book by the half-reactions The sign is reversed when the reaction is reversed |
Cell Potential | The energy needed for electrons to move to the cathode Listed in the data book by the half-reactions Do not change the signs from original The cathode — the anode |
S.H.E. | Standard Hydrogen Electrode is the reference point for the net voltage of other half-reactions in the redox table. If the standard is changed, the difference in voltage potential will also stay the same. |
Line Notation | A way of abbreviating the components of a cell. Single line indicates change is state Reactants come before the products Double line indicates a bridge or separation Anode is written before cathode (oxidation before reduction) |
Electrolysis of Water | Shows how the reduction half -reaction for water and oxidation half-reaction for water join together to create 2H2O=2H2+O2 Remember that Hydrogen ions and hydroxide ions add together to form water |
Chloride Anomoly | When the strongest reducing agent is between water and chloride, the chloride half-reaction is used. |
Uses for Electrolysis | To protect precious metals from corrosion To produce metals from salts To remove precious metals from other substances |
Down's Cell | When there is electrolysis of a molten salt and a molten metal is gathered as the product. Has a different set-up and usually has a gas outlet for the other product. |
Corrosion Prevention | 1. Prevent Interaction 2. Paint or Coat metal 3. Galvanize metal |
Sacrificial Anodes | Is also called cathodic protection and uses a stronger reducing agent so a different substance gets oxidized instead. |
Cell Stoichiometry | Uses the formula: Ne = It/F Faraday's Constant is 96500 C/mol of e- |
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