119. The nitrogen content oforganic compounds can be determinedbytheDumas method. Thecompound inquestion isfirstreactedbypassage over hot CuO(s):HotCompound----c>N2(g)+COig)+H20(g)(uo(.<)The product gas isthen passed through aconcentrated solutionofKOH toremove theCO2,After passage through theKOH so-lution, thegas contains N2andissaturated with water vapor. Inagiven experiment a0.253-g sample ofacompound produced31.8 mL N2saturated with water vapor at 25°C and 726 torr.What isthemass percent ofnitrogen inthecompound? (Theva-por pressure ofwater at25°C is23.8 torr.)120. An organic compound containing only C, H, and N yields thefollowing data.i.Complete combustion of35.0mgofthecompound produced33.5 mgCO2and 41.1 mg H20.ii.A 65.2-mg sample of the compound was analyzed fornitrogen by the Dumas method (see Exercise 119), giving35.6 mL N2at740. torr and 25°C.iii.The effusion rate ofthe compound as agas was measuredandfound tobe24.6mL/min. Theeffusion rateofargon gas,under identical conditions, is26.4 mUmin.What isthe molecular formula ofthecompound?121. Atmospheric scientists oftenusemixing ratios toexpress thecon-centrations of trace compounds in air. Mixing ratios are oftenexpressed asppmv (parts per million volume):fvolofXatSTP6ppmv0X=X 10total volofairatSTP
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