electrochemistry
electrochemistry
electrochemical cell anode: the electrode where oxidation occurs cathode: the electrode where reduction occurs
Salt Bridge
Salt Bridge
it is an upturned U-shaped glass rod that contains a saturated solution of an inert electrolyte mixed with agar-agar powder.
we use agar-agar as it retains the ions' ability to move with the same freedom as if they were in water but ensures that there is no mixing of the solutions or change in the concentrations which would lead to a change in the EMF of the cell.
salts are chosen based on inertness: it should form a highly soluble salt such that the ions do not interfere by forming precipitates.
it should also be a strong electrolyte (complete dissociation)- maximum electrical efficiency.
its ions should have the same ionic mobility if their mobility is not the same it causes a liquid junction potential- where the salt bridge acts as its own little battery against the main battery and hence decreases voltage and makes the battery weak and inefficient.
potassium chloride is preferred over sodium chloride because it has the one-to-one mobility ratio while sodium is smaller it has a larger water cloud surrounding it and hence floats a little bit slower than chloride.