chemistry Csir ugc

Wednesday, 25 July 2012

For organic chemistry including basics

For organic chemistry including basics

http://www.chemhelper.com/

Vilsmeier reaction

http://www.organic-chemistry.org/namedreactions/vilsmeier-reaction.shtm

Introduction to Matter

Introduction to Matter

Matter
"Matter is the physical material of the universe; it is anything that occupies space and has mass"
Matter can exist in three physical states:

gas or vapor
liquid
solid

Gas
No fixed volume or shape - it conforms to the volume and shape of its container. Gases can be compressed or expanded to occupy different volumes.
Liquid
A liquid has a distinct volume, independent of its container, but it has no specific shape. It assumes the shape of the container it is in. Liquids cannot be appreciably compressed.
Solid
A solid has a definite shape and volume; it is rigid. Solids cannot be appreciably compressed.
Substances
A pure substance has a fixed composition and distinct properties. Most matter we come in contact with in our daily lives is not a pure substance, but a mixture of substances.
Physical and Chemical Properties
Every pure substance has a unique set of properties - characteristics which allow us to distinguish it from other substances. These properties fall into two general categories: physical and chemical.
Physical properties - properties we can measure without changing the basic identity of the substance.
Chemical properties - describe the way a substance may change or "react" to form other substances.
Physical and Chemical Changes
Substances can undergo various changes in properties, these changes may be classified as either physical or chemical.
Physical changes - a substance changes its physical appearance but not its basic identity. All changes of state (e.g. solid to liquid to gas) are physical changes.
Chemical changes - also known as chemical reactions, a substance is transformed into a chemically different substance.
Mixtures
Mixtures refer to combinations of two or more substances in which each substance retains its own chemical identity and hence its own properties.
Heterogenous mixtures are not uniform throughout the sample, and have regions of different appearance and properties
Homogenous mixtures are uniform throughout the sample, however, the individual substances retain their individual chemical and physical nature. Homogenous mixtures are also called solutions, however, the most common type of solution is described by a solid (the solute) dissolved in a liquid (the solvent).
An important characteristic of mixtures is that the individual components retain their physical and chemical properties. Thus, it is possible to separate the components based on their different properties. For example, we can separate ethanol from water by making use of their different boiling temperatures, in a process known as distillation.

Monday, 25 June 2012

DID YOU KNOW

Did you know that parrots can be trained to say up to 200 words and short phrases. In fact their ability to mimic human language is so well known that many parrot owners initially purchase the bird for this reason alone.

The truth however is that like most talking birds they’re not really talking but mimicking the sounds they hear around them. They certainly don’t have any real understanding of the words they repeat and what’s more interesting is that parrots as a species are not the best of the bird mimickers.

Mynah Bird

Yes that’s right the top word mimic is actually the Mynah bird. Their ability to create amazingly realistic human and non human sounds such as words, coughs, sneezes and even cell phone ring tones is well documented.
Other birds that are extremely intelligent and known to mimic human words are crows, ravens and jackdaws. Although their abilities are less publicized.