A).What is a salt bridge? Explain its function in electrochemical cell.
B). Outline the basic difference between a galvanic cell and an electrolysis cell.
A) A salt bridge is a device that connects the two half-cells in an electrochemical cell. It is typically made of an inert electrolyte (such as potassium chloride or sodium sulfate) suspended in a gel or liquid. The function of a salt bridge is to allow the flow of ions between the two half-cells, which maintains the electrical neutrality of both cells and prevents the buildup of a charge. Without a salt bridge, the reaction would quickly come to a halt because the build-up of positive or negative charge in each half-cell would inhibit further electron transfer.
B) The basic difference between a galvanic cell and an electrolysis cell is that a galvanic cell (also known as a voltaic cell) converts chemical energy into electrical energy, while an electrolysis cell converts electrical energy into chemical energy. In a galvanic cell, a spontaneous redox reaction occurs, and electrons flow from the anode to the cathode through an external circuit, generating an electrical current. In an electrolysis cell, an external power source (such as a battery) provides enough energy to overcome the potential energy barrier of a non-spontaneous redox reaction, and electrons are forced to flow from the cathode to the anode. This process is used to produce useful products, such as hydrogen gas or metal ions, by breaking down a compound into its constituent elements.
A) A salt bridge is a component of an electrochemical cell that acts as a pathway for the flow of ions between the two half-cells. It consists of an inverted U-shaped tube filled with an electrolyte solution, usually a salt solution. The salt bridge is typically made of a porous material such as a gel or a filter paper soaked in the electrolyte solution.
The main function of a salt bridge is to maintain electrical neutrality in the half-cells of the electrochemical cell. During the redox reaction occurring in the cell, the oxidation half-reaction releases electrons, while the reduction half-reaction consumes electrons. Without a salt bridge, the accumulation of positive ions in one half-cell and negative ions in the other half-cell would hinder the flow of electrons, ultimately leading to the cessation of the redox reaction.
The salt bridge allows for the migration of positive ions from the salt solution to the anode compartment (where oxidation occurs) and negative ions to the cathode compartment (where reduction occurs). This maintains electrical neutrality in both compartments, preventing charge buildup and maintaining a continuous flow of electrons between the electrodes.
B) The basic difference between a galvanic cell (also known as a voltaic cell) and an electrolysis cell lies in the direction of electron flow. In a galvanic cell, the spontaneous redox reaction generates an electric current, whereas in an electrolysis cell, an external electric current is used to facilitate a non-spontaneous redox reaction.
In a galvanic cell:
1. The redox reaction is spontaneous and releases energy.
2. Oxidation takes place at the anode, where electrons are produced.
3. Reduction takes place at the cathode, where electrons are consumed.
4. Electrons flow from the anode to the cathode through an external circuit.
5. The movement of electrons generates an electric current that can be utilized for various applications, such as powering electrical devices.
In an electrolysis cell:
1. The redox reaction is non-spontaneous and requires an external energy source.
2. Oxidation takes place at the anode, where electrons are consumed.
3. Reduction takes place at the cathode, where electrons are produced.
4. An external current is supplied to force the flow of electrons in the desired direction.
5. The movement of electrons drives the non-spontaneous reaction to occur, allowing for processes such as electroplating, electrolytic refining, or splitting water into hydrogen and oxygen.