Sciencedoze: Science, Education and Technology

Glasses are ceramic materials that are rigid like solids but which are not crystalline. Glass is also known as a supercooled liquid of infinitely high viscosity. The glass comes in the category of amorphous solid which is brittle and transparent. They are obtained by fusing a mixture of several metallic silicates or borates of sodium, potassium, calcium, and lead. Composition of Glass Glass is not a single compound. So, it does not have a fixed chemical formula but its general chemical formula is given below: xR2O.yMO.6SiO2 R = Alkali metal (Na, K, etc) M = Bivalent metal (Ca, Pb, etc) x and y = Number of molecules Properties of Glass 1. Glass is an amorphous solid that is its constituent particles are not arranged in any regular fashion. 2. Glass is brittle that is it can easily crack by applying little external force. 3. Glass may be transparent or translucent depending upon the compounds used in its manufacturing. 4. Glass melt over a range of temperature. 5. Glass is isotropic.

The concept of Inherent Safer Design (ISD) states that hazardous should be avoided instead of controlling them. This can be done by reducing the amount of hazardous material and the number of hazardous operations in the industrial plant. The statement "what you don't have cannot harm you" was given by a British chemical engineer Trevor Kletz in an article published in 1978 after the Flixborough disaster. This statement means that we should reduce the hazard instead of controlling them. For example,  If benzene is replaced by a green solvent then how can benzene affect us in the future (What you don't have cannot harm you). There are four principles of inherently safer design: 1. Minimisation This method of Inherent Safer Design states that we should use small quantities of hazardous materials or reduce the size of equipment operating under hazardous conditions like high temperature and pressure. For example, Nitroglycerine can be manufactured in a continuous pip

Green chemistry is the branch of chemistry which aims at the designing of chemical products and processes to reduce or eliminate the generation of hazardous substances. Green chemistry promotes the green process, a healthy environment, and sustainable development. So, Green chemistry works on some set of principles called "12 Principles of green chemistry" . These principles were formulated by Paul T. Anastas. 12 principles of green chemistry are given below: 1. Prevention of waste or by-products This principle of green chemistry states that we should minimise or eliminate waste by-products rather than cleaning the waste after it has been created. For example, the production of plastic by-products should be minimised instead of cleaning it after its production. We should make a proper plan to minimise the waste at every step of the chemical process. 2. Maximum incorporation of the reactants (starting materials and reagents) into the final product This principle of green