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Explain the estimation of nitrogen of an organic compound by a) Dumas method |
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Answer» Solution :ESTIMATION of nitrogen by Duma's method : In this method a known weight of organic COMPOUND is heated strongly with coarse cupric oxide. Then carbon and hydrogen get oxidised to `CO_(2)` and `H_(2)O` vapour respectively. Nitrogen is converted to `N_(2)` gas some nitrogen cnverted into its oxides, gets reduced by copper gauze to nitrogen. The liberated gases are passed over a solution of KOH. Then `O_(2)` gets absorbed. Nitroegen is collected over KOH solution and its volume is found out.  Calculation : Suppose 'a' g of organic compound gives V ml of `N_(2)` gas at room temp. TK. Vol. of `N_(2)` gas at STP is calculated as follows. `{:("Expt. conditions","STP condition"),(P_(1)=(P-p)" mm where",P_(2)=760 mm),("p = aqueous tension ",),(T_(1)=TK,T_(2)=273K),(V_(1)=V,V_(2)=?):}` `(P_(1)V_(1))/(T_(1))=(P_(2)V_(2))/(T_(2))` `rArr V_(2)=(P_(1)V_(1)T_(2))/(P_(2)T_(1))=((P-p)xxVxx273)/(760 xxT)=" x ml"` `"22,400 ml. of "N_(2)" at STP WEIGHS 28 g"` `therefore" x ml. of "N_(2)" at STP weighs .............."?` `=(x xx28)/(22,400)g` 'a' g of organic compound contains `(28 xx x)/(22400) g " of "N_(2)` `therefore"100 g of organic compound contains"`? `=(100)/(a)xx(28xx x)/(22400)" g of "N_(2)` |
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