8. What is chemical effect of electricity? Give some examples of chemical effects.

The chemical effect of electricity involves the triggering of chemical reactions by passing an electric current through a conductor or a solution. This process, known as electrolysis when it involves a liquid electrolyte, leads to the decomposition of chemical compounds and the liberation or deposition of elements. The chemical effects of electricity are fundamental to various industrial processes, environmental management, and everyday applications. Here are some examples and explanations of the chemical effects of electricity:

Electrolysis of Water:

One of the most straightforward examples of the chemical effect of electricity is the electrolysis of water. When an electric current is passed through water (usually containing an electrolyte, like salt, to improve conductivity), water decomposes into oxygen and hydrogen gases. At the cathode (negative electrode), hydrogen ions (H+) gain electrons (reduction) to form hydrogen gas (H2), and at the anode (positive electrode), water molecules lose electrons (oxidation) to form oxygen gas (O2) and hydrogen ions (H+). The overall reaction is:

2H2O(l)→2H2(g)+O2(g)2H2O(l)→2H2(g)+O2(g)

Electroplating:

Electroplating is a process that uses electrical current to reduce dissolved metal cations so that they form a thin coherent metal coating on an electrode. The object to be plated is placed at the cathode of an electrolytic cell, and the metal to be plated onto the object is placed at the anode or in the electrolyte solution. For example, silver plating on copper:

Ag+(aq)+e−→Ag(s)Ag+(aq)+e−→Ag(s)

Electrorefining:

This is a method used for refining metals, typically copper. It involves using an electrolytic cell to purify the crude metal. The impure metal is made the anode, and a pure strip of the metal is made the cathode. The electrolyte solution contains ions of the metal to be purified. Upon passing an electric current, pure metal from the anode dissolves into the electrolyte and is then deposited onto the cathode, leaving impurities behind.

Battery Operation:

Batteries convert chemical energy into electrical energy through redox reactions. In a simple zinc-carbon battery, for example, zinc is oxidized at the anode, and manganese dioxide is reduced at the cathode, producing a flow of electrons that provides electrical power to connected devices.

Electrochemical Cells:

These devices use the chemical effect of electricity to perform non-spontaneous chemical reactions. An example is the production of chlorine gas and sodium hydroxide from brine (saltwater) in the chlor-alkali process:

At the anode: 2Cl−→Cl2(g)+2e−2Cl−→Cl2(g)+2e−

At the cathode: 2H2O(l)+2e−→H2(g)+2OH−2H2O(l)+2e−→H2(g)+2OH−

Overall process: 2NaCl+2H2O→2NaOH+H2+Cl22NaCl+2H2O→2NaOH+H2+Cl2

These examples highlight the importance of the chemical effect of electricity in various scientific, industrial, and technological applications, demonstrating how it can be harnessed to drive chemical reactions, refine metals, deposit materials, and generate useful products.