Gen Chem Flashcards
what is the purpose of a salt bridge
It is to exchange anions and cations to balance, or dissipate, newly generated charges
What remains consistent in both electrolytic and galvanic cells?
All types of electrochemical cells have a reduction reaction occurring at the cathode, an oxidation reaction occurring at the anode, current flows from cathode to anode, and electron flow from anode to cathode.
Whereas galvanic cells house ____ oxidation -reduction reactions which enerate electrical energy, electrolytic cells house _____ reactions, which require the input of energy to proceed.
galvanic= spontaneous electrolytic= nonspontaneous
Electrolysis
is nonspontaneous, so the electrode can consist of any material so long as it can resist the high temperatures and corrosion of the processes
Faraday’s laws
States that the liberation of gas , and deposition of elements on electrodes is directly proportional to the number of electrons being transferred during the oxidation - reduction reaction. Here normality or gram equivalent weight is used. These observations are proxy measurements of the amnt of current flowing in a circuit.
Faraday constant
The charge carried by 1 mole of electrons can be calculated by multiplying 1 coulomb (1x10^(-19)) x (6.02x10^23) electrons. The faraday constant is equivalent to 96,485 C/ mol. round up to 10^5.
Electrodeposition equation
summarizes the process of determining the number of moles of element being deposited on a plate.
molM= It/nF.
mol M= amnt of metal ion being deposited at a specific electrode, I is current, t is time, n is number of electron equivalents, F is faraday constant
Concentration Cell
A special type of galvanic cell , except the electrodes are chemically identical. So, the current generated is a function of the concentration gradient established between the two solutions surrounding the electrodes. It results in a potential difference between the two compartments and drives the movement of electrons in the direction that results in equilibration of the ion gradient. So, Voltage or emf is 0 when the concentrations are equal. Calculate voltage with the nernst equation.
A rechargeable cell is once that can function as both a
galvanic and electrolytic cell
Lead- Acid battery
Pb anode and porous Pb02 cathode, connected by conductive paterial (H2SO4). When it is discharged, it consists of 2 PbSO4 electroplated lead electrodes with a dilute concentration of H2So4.
Galvanic and Electrolytic Cell Concept
In a galvanic cell, the anode is negative and the cathode is positive. In an electrolytic cell, the anode is positive and the cathode is negative. This is because an external source is used to reverse the charge of an electrolytic cell. However, in both types of cells reduction occurs at the cathode and oxidation occurs at the anode; cations are attracted to the cathode and anions are attracted to the anode .
The species in a reaction that will be oxidized or reduced can be determined from the
reduction potential of each species, the tendency of a species to gain electrons and to be reduced. The more positive the potential, the greater tendency to be reduced.
