dissolved oxygen

Corrosion is defined as an attack on a material as a result of chemical, frequently electrochemical reaction, with the surrounding medium. According to this definition, the term corrosion can be applied to all materials, including non-metals. But in practice, the word corrosion is mainly used in conjunction with metallic materials. Why do metals corrode? Apart from gold, platinum and a few others, metals do not occur in the nature in their pure form. They are normally chemically bound to other substances in ores, such as sulphides, oxides, etc. Energy must be expended (e.g. in a blast furnace) to extract the ... Read more

ENVIRONMENT POLLUTION defined as ‘an addition or excessive addition of certain materials to the physical environment (water, air and lands), making it less fit or unfit for life’. Pollutants are the materials or factors, which cause adverse effect on the natural quality of any component of the environment. Classifications 1. According to the form in which they persist after release into the environment. • Primary pollutants: These persist in the form in which they are added to the environment e.g. DDT, plastic. • Secondary Pollutants: These are formed by interaction among the primary pollutants. For example, peroxyacetyl nitrate (PAN) is ... Read more