aqueous solution

Corossion of metals

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

Acids and bases

Acid An acid is a substance which forms H+ ions as the only positive ion in aqueous solution. Examples:- Hydrochloric acid dissolved in water forms H+ and Cl– ions   HCl —> H+ + Cl–   Sulphuric acid dissolved in water forms H+ and SO42- ions   H2SO4 —>2H+ + SO42-   Nitric acid forms H+ and NO3– ions when dissolved in water   HNO3 —> H+ + NO3–   Ethanoic acid,also know as acetic acid, forms H+ and CH3COO– ions in water   CH3COOH —> H+ + CH3COO– Acetone, also known as propanone, doesn’t form any ions in water, so it isn’t an acid. CH3COCH3 just dissolves in water. Methane, CH4, doesn’t form any ions ... Read more