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Give information about catalysis and explain about promoters. |
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Answer» Solution :Potassium CHLORATE, when heated strongly decomposes slowly giving dioxygen. The decomposition occurs in the temperature range of 653-873 K. `2KClO_(3)rarr 2KCl+3O_(2)` However, when a little of manganese dioxide is added, THC decomposition takes place at a considerably lower temperature range, i.e. `473-633 K` and also at a much accelerated rate. The added manganese dioxide remains unchanged with respect to its mass and composition. In a similar manner the rates of a number of chemical reaction can be altered by the mere presence of foreign substance. The systematic study of the effect of various foreign substances on the rates of chemical reactions was first made by Berzelius in 1835. He suggested the term catalyst for such substances. Substances, which ACCELERATE the rate of a chemical reaction and themselves remain chemically and quantitativel unchanged after the reaction are known as catalysts and the phenomenon is known as catalysis. Promoters and poisons : Promoters are substance that enhance the activity of a catalyst while poisons decrease the activity of a catalyst. For EXAMPLE, in Haber.s process for manufacture of ammonia, molybdenum acts as a promoter for iron which is used as a catalyst. `N_(2(g))+3H_(2(g))OVERSET(Fe_((s)))underset(Mo_((s)))rarr2NH_(3(g))` |
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