Oxidation And Reduction Flashcards
What is oxidation
Oxidation is the addition of oxygen, removal of hydrogen, loss of electrons, increase in oxidation number
What is reduction
Reduction is the addition of hydrogen, removal of oxygen, gain of electrons, decrease in oxidation number
What is a disproportional reaction
It is a reaction in which the same substance is oxidized and reduced
What are the applications of electrochemistry
Battery, control of corrosion, elctrolysis and metallurgy
What is electrochemistry
It is the branch of chemistry that deals with the inter conversion of electrical and chemical energy
Metals are good oxidizing agents
True/ false
False
What are the types of electrochemical cells and what do they do
Voltaic/galvanic: produces electricity in a spontaneous reaction
Electrolytic cell: produces a chemical change in a non-spontaneous reaction
What is Gibbs free energy
It is the max useful work done by a system
What is the relationship between Gibbs free energy and spontaneity of a reaction
When G is -ve, reaction is spontaneous
When G is +ve, reaction is non spontaneous
When G = 0, reaction is at equilibrium
Relationship between Gibbs free energy and the electrode potential of a cell
When E is -ve, G is +ve
When E is +ve, G is -ve
What is a potentiometer
It is an instrument that measures the potential difference of a cell by generating a voltage equal to that of the cell
What is the anode
It’s the positive electrode of a cell, oxidation takes place there and electrons leave
What is the cathode
It is the negative electrode, reduction takes place, electrons enter the cell
What are concentration cells and what is usually the electrode potential
They are volcanic cells with the same species on the two half cells but with different concentrations
E⁰ = 0
What is electrolysis
Electrolysis is a process of driving a reaction in a non spontaneous direction by passing current through it
What are the differences between voltaic and electrolytic cells
The electron flow is reversed
The anode does opposite jobs
The cathode does opposite jobs
What are the factors that affect discharge of elements
The concentration of the ions in the electrolyte
The nature of the electrode
The position of the element in the electrochemical series
State faraday’s laws of electrolysis
1st law states that the mass of an element liberated during electrolysis is proportional to the quantity of electricity passing through the cell.
2nd law states that when the same quantity of electricity is passed through various electrolytes, the masses of the ions deposited at the electrode is directly proportional to their chemical equivalence
How do you calculate chemical equivalence
Molar mass/ number of moles of electrons needed
What is the electrolytic process of extracting aluminium from bauxite ( anhydrous Al2O3) called
Hall process
