describe the estimation of nitrogen by dumans method
Answers
Description:
The two available methods for the estimation of nitrogen are: (i) Dumas Method and (ii) Kjeldahl’s method.
1. Dumas Method − When nitrogen containing organic compound is heated with excess copper oxide in an atmosphere of CO2, free nitrogen is obtained in addition to CO2 and water. Chemical reactions are −
C + 2CuO → CO2 + 2Cu
2H + CuO → H2O + Cu
Nitrogen + CuO → N2 + oxides of nitrogen
Any oxides of nitrogen formed during the reaction are reduced to N2 by passing it over heated copper gauze.
Oxides of nitrogen + Cu → N2 + CuO
The mixture of gases is collected over KOH solution that absorbs CO2.
N2 is collected in the upper part of the graduated tube.
The net reaction can be given as −
CxHyNz + (2x +
y
/
2
)CuO → xCO2 +
y
/
2
H2O +
z
/
2
N2 + (2x +
y
/
2
)Cu
Dumas Method
