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Discuss about dumas method and principles for estimation of N present in organic compound |
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Answer» Solution :Estimation of nitrogen by dumas methods: The nitrogen containing organic compound, when heated with copper oxide in an ATMOSPHERE of carbon dioxide, yields FREE nitrogen in addition to carbon dioxide and water Reaction: `C_(x) H_(y) N_(z) + (2x + (y)/(2)) CuO overset(Delta)rarr xCO_(2) + (y)/(2) H_(2)O + (z)/(2)N_(2) + (2x + (y)/(2)) Cu` Traces of nitrogen oxides formed, if any, are reduced to nitrogen by passing the gaseous mixture over a heated copper gauze. The mixture of gases so produced is collected over an aqueous solution of POTASSIUM HYDROXIDE which absorbs carbon dioxide. Nitrogen is collected in the upper part of the graduated tube  Calculate of % composition of nitrogen: Mass of taken organic compound = m gm Volume of nitrogen collected `= V_(1) mL` Laboratory temperature `=T_(1)K` `((T_(1) "temperature"),("the pressure"),("of" N_(2)"gas"))= p_(1) = [(("Atmospheric"),("pressure"))- (("Aqueous"),("tension"))]` Volume of `N_(2)` at STP= V mL Atmospheric pressure at STP= 760mm Hg Temperature at STP= T= 273K `:. (p_(1)V_(1))/(T_(1)) = (PV)/(T) = (760 XX V)/(273)` `:. V= (p_(1) V_(1))/(T_(1)) xx (273)/(760)` Volume of 22400mL gas at STP= Molecules mass `:.` mass of 22400mL `N_(2)` gas at STP= 28gm so, mass of V mL `N_(2)` at STP- mass of `N_(2)` at STP `= (28 xx V)/(22400)gm` % of nitrogen `= (28 xx V xx 100)/(22400xx m)` `=(28)/(22400). (p_(1)V_(1) xx 273)/(T_(1) xx 760) xx (100)/(m)` `= 0.0449 xx (p_(1)V_(1))/(T_(1)m)` |
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