QUANTITATIVE ANALYSIS 459 Thus i gram-molecule of urea (60 g.) should give 22-4 litres of nitrogen at S.T.P., or i g. of urea should give 373 ml. of nitrogen. Actually however urea in solution always gives a small amount of ammonium cyanate with which it is in equilibrium, and consequently the full amount of nitrogen (in accor-dance with the above equation) is not evolved: it is found that i g. of urea gives actually 357 ml. of nitrogen at S. T. P. (i.e., 95-7% of the theoretical), and all calculations should therefore be based on this value. A convenient form of apparatus, particularly for large classes, is shown in Fig. 84; it is identical with that used for the determination of the equivalent weight of metals by hydrogen evolution. A and H are glass tubes connected together by the rubber tubing J and securely fastened to the board B. The tube A is graduated from the top downwards. The tube H carries near its base a short outlet tube, to which is con-nected a piece of rubber tubing
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.