Question

what is the salt bridge? mention its function.

Answer 1

1. a tube containing an electrolyte (typically in the form of a gel), providing electrical contact between two solutions.

2.

a link between electrically charged acidic and basic groups, especially on different parts of a large molecule such as a protein.

The purpose of a salt bridge is not to move electrons from the electrolyte, rather it's to maintain charge balance because the electrons are moving from one-half cell to the other.



The electrons flow from the anode to the cathode. The oxidation reaction that occurs at the anode generates electrons and positively charged ions. The electrons move through the wire (and your device, which I haven't included in the diagram), leaving the unbalanced positive charge in this vessel. In order to maintain neutrality, the negatively charged ions in the salt bridge will migrate into the anodic half cell. A similar (but reversed) situation is found in the cathodic cell, where Cu2+CuX2+ions are being consumed, and therefore electroneutrality is maintained by the migration of K+KX+ ions from the salt bridge into this half cell.

Regarding the second part of your question, it is important to use a salt with inert ions in your salt bridge. In your case, you probably won't notice a difference between NaClNaCl and KNO3KNOX3 since the Cu2+CuX2+ and Zn2+ZnX2+ salts of Cl−ClX− and NO3−NOX3X−are soluble. There will be a difference in the liquid junction potential, but that topic is a bit advanced for someone just starting out with voltaic/galvanic cells.

Answer 2

Explanation:

$\huge\mathtt\red{Answer}$

$\longrightarrow$ A commonly used form of salt bridge consists of a glass U- tube containing semi- solid paste of either KCl, $KNO_3$ or $NH_4Cl$ in gelatin or agar-agar jelly.

$\longrightarrow$ The electrolytes that are often used in salt bridge are called inert electrolytes which are supposed:

not to interact chemically weather of the solutions present in a anodic or cathodic Chambers.

not to interfere with overall cell reaction.

only those electrolytes can be used in a Salt Bridge in which mobility of Ions is almost the same.

Example, KCl, $K_2SO_4$, etc.

$\longrightarrow$ A salt bridge carries out two important functions:

It allows only flow of Ions through it. Thus, the circuit is completed.

It also maintains the electrical neutrality.