Final answer:
Zinc in amalgam serves as a sacrificial anode to prevent corrosion and to improve mechanical and corrosion resistance in dental fillings. Its high activity as a metal also makes zinc beneficial in chemical reactions as a reductant.
Step-by-step explanation:
The purpose of Zn in amalgam, particularly in dental and industrial applications, is multifaceted. Zinc acts as a sacrificial anode in an electrochemical cell, preventing the corrosion of other metals. In dental amalgams, which are made of silver and other metals such as tin and copper, the mercury bonds with these metals to form a stable filling material. However, due to the toxicity of mercury, there is a significant decrease in using mercury-based amalgams, and zinc's role in these amalgams is to improve their mechanical properties and corrosion resistance. In specialized chemistry applications, zinc amalgam (Zn(Hg)) is used as a reductant because zinc is a more active metal; it donates electrons in reduction reactions, helping to purify other metals or to perform chemical syntheses.