Unit 10 - Redox - Regents Flashcards
Definition of Redox Reactions (2)
- e- are removed from one particle and transferred to another
- Oxidation & Reduction must occur at the same time
(E produced when e- go from hi - lo ES )
Definition of Oxidation
Loss of e-
Definition of Reduction
Gain of e-
Why must reduction and oxidation occur at the same time?
Law of Conservation of Charge
What is an Acronym to Remember Oxidation & Reduction?
LEO say GER
Loss of Electrons - Oxidation
Gain of Electrons - Reduction
What are Oxidation Numbers/States? (5)
- Represents num. of e- gained/lost
- When forming a Chemical Bond
- Changes in num indicate oxidation & reduction occured
- Increase in num - element oxidized
- Decrease in num - element reduced
What are the 8 Rules of assigning Oxidation Numbers? (8)
- Uncombined elements num = 0 (Diatomic too!)
- Monotomic ions in ionic compounds num = charge
- Group 1 metals = +1
- Group 2 metals = +2
- O = -2, EXCEPT in peroxides (H2O2) = -1
- H = +1, EXCEPT when paired w/ metals = -1
- Overall Charge adds up to 0
- Overall Charge of Polyatomic Ion adds up to listed charge
Definition of Reducing Agent (2)
- The thing that gets oxidized
- Provides e- to others (reduces others), loses e- itself (oxidizes itself)
Definition of Oxidizing Agent (2)
- The thing that gets reduced
- Steals e- to others (oxidizes others), gains e- itself (reduces itself)
Definition of Activity Series (4)
- Determines Activity of M & NM
- Higher M lose e- more easily
- Higher NM gains e- more easily
- Higher element replace lower one in comp.
Definition of Half Rxns (3)
- Shows just oxidation/reduction occurring in redox rxn
- Oxidation 1/2 Rxn = X -> X + _e-
- Reduction 1/2 Rxn = X + _e- -> X
How do you balance a simple redox rxn? (8)
- Write 2 Half Rxns
- Balance the elements itself
- Add coeff. for same # of elem. on both sides
- Once coeff. added, change the change of e-
- Repeat on other equation
- Compare e- lost & gained between 2 rxns
- Add coefficients to make e- = on both sides
- Recombine the half rxns
Definition of Electrochemical Cells (3)
- System where chemical rxns & electrical E interact
- Consists of 2 electrodes in electrolyte solution
- Voltaic Cell & Electrolytic Cell
Definition of Voltaic Cells (6)
Classification, Part of Cell, Function, How, How, How
- Electrochemical Cell
- Spontaneous Rxn, no external energy source
- Converts Chemical E to Electrical E
- Relies on Redox Rxns to Produce Electricity
- One side loses e- & other side gains e-
- This flow of electrons creates electricity
What are components of Voltaic Cells?
- Anode
- Cathode
- Voltmeter - Measure voltage (electric potential difference) between anode/cathode
- External Circuit - Wire, connects anode & cathode, allowing e- to flow
- Salt Bridge - tube filled with a salt solution that allows the flow of ions between the two half-cells to maintain electrical neutrality.
- Half - Cells
Definition of Anode (5)
(Ex: Pb²⁺)
Classification, Definition, Outline of Ex, Charge, Size
- Electrode
- Where oxidation occurs
- Pb electrode gets oxidized, losing e- & form Pb²⁺ ions
- Anode Compartment gets more positive bc of loss of negativity & positive ion buildup
- Pb Electrode gets smaller bc its losing material (oxidation) & Pb²⁺ repel each other
Definition of Cathode (5)
(Ex: Ag+)
- Electrode
- Where reduction occurs
- Ag electrode gets reduced, gaining e-
- Cathode comp. is more negative bc Ag⁺ gain e- from circuit
- Cathode gets bigger bc Ag+ gains e-, conv. to Ag & deposited
What is the typical e- flow?
Anode to Cathode
e- move away from Anode, oxidizing it, and moves to the Cathode, reducing it
Definition of Salt Bridge (2)
- Tube filled w/ salt solution
- Allows flow of ions between two half-cells
Definition of Half Cell (2)
- Each electrode & corresponding electrolyte solution form a half-cell
- Anode and cathode are in separate half-cells
Definition of Electrolytic Cell (4)
Classification, Process, Function, AKA
- Electrochemical Cell
- Process is Electrolysis
- Requires electrical energy to produce chemical change
- AKA use of electricity to produce a redox rxn
What are distinguishing parts between Electrolytic Cells & Voltaic Cells
Voltaic: 2 Containers, Voltmeter, Salt Bridge
Electrolytic: 1 Container, No Voltmeter & Salt Bridge, External Power Source
What is a great way to remember what occurs at the anode or cathode?
Red Cat
An Ox
How can the Activity Series relate to a Voltaic Cell?
- Higher element is oxidized, so it’s ANODE
- Lower element is reduced, so it’s CATHODE
- e- flow from HIGHER metal to LOWER metal (anode to cathode)
(Higher to Low is Spontaneous)
