General Chemistry Ch 11. Oxidation-Reduction Reactions Flashcards
Oxidation
Loss of elections
Reduction
Gain of electrons
Oxidation-reduction reaction
aka redox reaction, when an oxidation and reduction are paired together
Oxidizing agent
Facilitates the oxidation of another compound and is reduced itself in the process, common ages almost all contain oxygen or a similarly electronegative element
Reducing agent
Facilitates the reduction of another compound and is itself oxidized in the process, often contain metal ions or hydrides
Assigning oxidation numbers
Free element or diatomic species - 0
Monatomic ion - charge of the ion
Group IA metals - +1
Group IIA metals - +2
Group VIIA elements - -1 (unless with an element of higher electronegativity)
Hydrogen - +1 (unless paired with less electronegative element –> then -1)
Oxygen - usually -2 except in peroxides (-1) or in compounds with more electronegative elements
Oval charge of the compound = the sum of the oxidation numbers of all atoms present
Half-reaction method
aka ion-electron method, method for balancing redox reactions where you
1) separate the two half reactions
2) balance the atoms of each half reaction, start with all except O and H, in acid solution balance H and O using water and H+, in basic solution balance using water and OH-
3) balance the charges of each half reaction by adding electrons as necessary to one side of the reaction
4) Multiply the half reactions as necessary to obtain the same number of electrons in both half reactions
5) add the alf reactions, canceling out terms on both sides
6) Confirm mass and charge are balanced
Ion-electron method
aka half-reaction method, method for balancing redox reactions where you
1) separate the two half reactions
2) balance the atoms of each half reaction, start with all except O and H, in acid solution balance H and O using water and H+, in basic solution balance using water and OH-
3) balance the charges of each half reaction by adding electrons as necessary to one side of the reaction
4) Multiply the half reactions as necessary to obtain the same number of electrons in both half reactions
5) add the alf reactions, canceling out terms on both sides
6) Confirm mass and charge are balanced
Complete ionic equation
Accounts for all of the ions present in a reaction, to write a complete ionic reaction, split all aqueous compounds into their relevant ions, keep solid salts intact
Net ionic equations
Ignore spectator ions to focus only on the species that actually participate in the reaction, to obtain a net ionic reaction, subtract the ions appearing on both sides of the reaction, which are the spectator ions, for runs with no aqueous salts the net ionic equation is generally the same as the overall balanced reaction, for double displacement reactions that do not form a solid salt there is no net ionic reaction because all ions remain in solution and do not change oxidation number
Spectator ions
Ions that appear on both sides of a reaction
Disproportionation reactions
aka disputation reactions, a type of redox reaction in which one element is both oxidized and reduced, forming at least two molecules containing the element with different oxidation states
Oxidation-reduction titrations
Similar in methodology to acid-base titrations, follow transfer of change, indicators change color when certain voltages of solutions are achieved
Potentiometric titraiton
Form of a redox titration in which a voltmeter or external cell measures the electromotive force (emf) of a solution, no indicator is used and the equivalence point is determined by a sharp change in voltage
