when set the powder on fire, heat is liberated during a reaction. On the other hand ozone is a powerful oxidising agent and it reacts with many substances under conditions where oxygen will not react. For example, it oxidises potassium iodide to iodine. This reaction is quantitative and can be used for estimation of ozone.
O + 2KI + H O 2KOH + O I Ozone is commonly used for oxidation of organic compounds. In acidic solution ozone exceeds the oxidising power of fluorine and atomic oxygen. The rate of decomposition of ozone drops sharply in alkaline solution. Uses: .
Oxygen is one of the essential component for the survival of living organisms. . It is used in welding (oxyacetylene welding) . Liquid oxygen is used as fuel in rockets etc...
. . Allotrophic forms of sulphur Sulphur exists in crystalline as well as amorphous allotrophic forms. The crystalline form includes rhombic sulphur (α sulphur) and monoclinic sulphur (β sulphur).
Amorphous allotropic form includes plastic sulphur (γ sulphur), milk of sulphur and colloidal sulphur. Rhombic sulphur also known as α sulphur, is the only thermodynamically stable allotropic form at ordinary temperature and pressure. The crystals have a characteristic yellow colour and composed of S molecules. When heated slowly above ⁰C, it converts into monoclinic sulphur.
Upon cooling below ⁰C the β form converts back to α form. Monoclinic sulphur also contains S molecules in addition to small amount of S molecules. It exists as a long needle like prism and is also called as prismatic sulphur. It is stable between ⁰C - ⁰C and slowly changes into rhombic sulphur.
When molten sulphur is poured into cold water a yellow rubbery ribbon of plastic sulphur is produced. They are very soft and can be stretched easily. On standing (cooling slowly) it slowly becomes hard and changes to stable rhombic sulphur. Sulphur also exists in liquid and gaseous states.
At around ⁰C the monoclinic sulphur melts to form mobile pale yellow liquid called λ sulphur. The vapour over the liquid sulphur consists of %