ELECTROCHEMISTRY Flashcards
(39 cards)
State the electrochemical series of metal from most reactive to least reactive
Li, K, Ca, Na, Mg, Al, Zn, Cr, Fe, Ni, Sn, Pb, H2, Cu, Hg, Ag, Pt, Au
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 the anode
It’s the positive electrode of a cell, oxidation takes place there and electrons leave
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
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 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
What is Gibbs free energy
It is the max useful work done by a system
What is the cathode
It is the negative electrode, reduction takes place, electrons enter the cell
What is electrolysis
Electrolysis is a process of driving a reaction in a non spontaneous direction by passing current through it
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 are the differences between voltaic and electrolytic cells
The electron flow is reversed
The anode does opposite jobs
The cathode does opposite jobs
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
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
How do you calculate chemical equivalence
Molar mass/ number of moles of electrons needed
Hall process
What is the electrolytic process of extracting aluminium from bauxite ( anhydrous Al2O3) called
When do you consider concentration of ions over position in the electrochemical series in the preferential discharge of ions
You do that when the elements between them is two or less
The more reactive/electropositive metals are more likely to be discharged during electrolysis
True/False
False
What are electrodes
They are conductors through which electric current enters or leaves the electrolyte
State the ionic theory
The ionic theory (by arrhenius) states that when an electrolyte is melted/dissolved in water, some or all of its molecules dissociate into freely moving charged particles(ions)
This process is called ionization
What was the fault found in the ionic theory
It was discovered by x-ray diffraction that electrolytes contained these charged particles in them and are just separated when melted or dissolved
What are inert electrodes
Inert electrodes are electrodes that do not take part in the electrolytic reaction
Give examples of inert electrodes and what element attacks them
Platinum - chlorine
Carbon - oxygen
