Difference Between Electroplating And Electrolysis
Electroplating is the process of coating, or plating, an object with metal by using an electric current. Things are given metal coatings to make them look better and to protect them from rust. Familiar examples of electroplated objects include gold-plated jewelry, silver-plated tableware (spoons, forks, knives), and chromium-plated automobile bumpers. The objects to be plated, as well as the plating materials, are usually metals.
To understand what happens during electroplating, you need to know something about atoms and the way they behave. At the center of every atom is a nucleus, which has a positive electric charge. Spinning around the nucleus are negatively charged electrons. An ordinary atom has exactly as many positive charges as negative charges. All the charges balance, and the atom as a whole has a neutral electrical charge.
Electrolysis is a process in which an electric current passes through a liquid, causing chemical reactions to occur. If the liquid is water, electrolysis breaks water molecules into hydrogen and oxygen. If the liquid contains metals, electrolysis removes the metals from the liquid. Electrolysis has many practical uses, especially in industry.
How electrolysis works. Electrolysis takes place in a device called an electrolytic cell. An electrolytic cell consists of two solid electrical conductors, called electrodes, placed in a liquid. Most electrodes are metal or carbon rods. The liquid may be water or another substance that conducts electric current. The liquid may contain dissolved substances called electrolytes that increase its ability to conduct electric current.
Wires connect the electrodes to the terminals of a battery or another source of direct current (current that flows in one direction). Cathode is the electrode connected to the negative terminal. It transfers electrons, which are negatively charged, from the battery to the electrolytic cell. Anode is the electrode connected to the positive terminal. It transfers electrons from the electrolytic cell back to the battery. The movement of electrons produces an electric current.
The liquid in the electrolytic cell contains ions. Ions are atoms or molecules that have lost or gained an electron, becoming positively or negatively charged. Positive ions are attracted to the cathode of the electrolytic cell, and negative ions are attracted to the anode. The movement of ions carries electric current between the electrodes.
At the cathode, electrons are transferred to atoms or molecules in the liquid. This process, called reduction, causes chemical reactions to take place. For example, if a water molecule near the cathode gains an electron, one of its hydrogen atoms splits off and sticks to the cathode. It soon joins another hydrogen atom, forming a molecule of hydrogen gas. The hydrogen gas bubbles out of the water. If the liquid contains ions of a metal, such as gold or silver, reduction removes the metal from the solution, causing a thin layer of the metal to form on the cathode.
At the anode, electrons are transferred from atoms or molecules in the liquid and join the current flowing toward the positive terminal of the battery. This transfer, called oxidation, also causes chemical reactions. For example, when water gives up electrons at the anode, oxygen atoms split from the water molecules and join to make oxygen gas. The gas bubbles out of the water.