An Easy DCI(g) Prep for the HCI(g)-DCI(g) IR Experiment The HCl(g)-DCl(g) IR spectrum analysis is an excellent pedagogical exercise for undergraduates. Unfortuna@,Vt is not always possible or practical t o carry out the traditionalvacuum line preparation of the DCl(g) sample using benzoyl chloride and D90. Ilsiny a lecture tank of H C I I ~ , ., I 0 rnl oiYY+%DD1, o wruum pumpnnd an IH g a i cell, n ynroussamplr cuntnininl: 1~8thllCl ~ n D('lcnn d he prepared m lers than 10 min. Toprrparethr sample, place the D1Oin s 125-ml Erlenmeyer tlnsk i n a h w d and saturate i t with HC'I Gas. Plnre the n u & ofnnrwcuattd IR xnarrll intuth~flnsk,alowlgopen thr irqxock t o pull in the acid vapors, close the stopcock, and run the spectrum. The solvation of HCI in DzO is quite exothermic. Thus, to avoid getting too much D20vapor into the gas cell, the solution should he below room temperature before attempting to fill the cell. The warm D20 vapor will condense in the cell when caoled and cause deterioration of the salt windows. Also, most of the HCI-DCI vapor will dissolve in the liquid. For economy of resourcesand time, the sarneDCI solution can be used for an entire class. Simply bubble the D20-DClsolution with HCI gas briefly before getting a new sample. The IR gas cell is opened and stared in a desiccator after each use and the D 2 0 solution is canned. different species in the solution.
Garry R. Buettner Wabash College Crawfordsville, IN 47933
524
Journal of Chemical Education
