Experimental meas urements, not previously reported in detail, of the vapor pressure of CH, and the differe nces in vapor press ures of CH. and the deuterom ethanes below the normal boiling point are presented. A critical revi ew of the literature relating to the vapor pressures of m ethane and the deu teromethanes is given. On the basis of the experim ental measurem ents and t he previous literature t he following best values are assigned to fix ed points on the vapor pressure curves. . Th e vapor-press ure ratios of the isoto pic m etha nes for m a nearl y geo metri c p rogressio n wi t h in creas ing d eute rium substitution. Dev ia t io ns of t heir mix t lll'eS fr om ideal solu t io ns arc very s m·a ll.
A Review of the Vapor Pressure of Methane and the Deuteromethanes
MethaneThe vapor pressure of solid and liquid methan e has been determined in various tempera! ure ranges by many investigators, and , in addi tion , t her e have b ee n sever al summari es of t he pu bli shed da ta. S. F. [12] and by Bl'ickwedde and Scott of t he National Bureau of tandards (section 2 of t his pap er ). D cterminations of t.h e tripl e poi.nt as Ii tcd in table 1 provide a fixed point t hrough whi ch an equation for the da ta should pass. Of Lh e reported determi ll ations, t he exLensiv e da ta from Clusiu ' labor atory ap pear to be besL l'epresen ted b y Lhe values 90.67 ± 0.03° K and 87.4 ± 0.1 mm , which were determin ed from a sLudy of the melLin g temperatul'e as a fun cLion of pressure. Th e value 90.660 ± 0.005° K and 87.60 ± O.I O mm. were foun d by Brickwedde and Scott wi Lh a carefully purified sample. The besL values of t he triple poin L Lemperature and press ure appeal' 1,0 be 90.66 ± 0.01 ° K and 87.50 ± 0.10 mm .In an attempt to r emedy this deficien cy t his r eview has been prepared in which the data from variou sources h ave been compared including those describ ed in section 2, previously unpublished, and available to non e of the previous reviewers except perhaps Rossini. An attemp t has been made to find equations which fit well t he best available data and at the same time pass t hrough selected b est values for the triple point, normal boiling point, and critical poin t.
The en e rgies of co mbu s ti on of AlB" and a-A lB" were me asured in a bomb . ca lor im e ter us in g Auorin e as th e ox idant. Major probl e ms of thi s inves tigation were the assessment of th e stat e and di s· tribution of impuriti es in the sa mpl es and the establi s hm e nt of the s toi c hiom etry of th e a luminum boride ph ase. W e obtain -16 ± .3 kcal mol -' and -48 ± 10 kcal mor' for th e heat s of formation of A I B, a nd a·AIB,", res pec tively. Th e unce rtainti es c it ed are th e overa ll ex pe rim e ntal errors. Their magnitud es a re c hi e Ay du e to uncertainti es in th e impurity co rrec tion appli ed and th e un ce rtainties in the heats of formation of th e co mbustion produc ts.
Bomb calorim e tri c meas ure ments a re reported for the co mbu stio n in flu orine of polytetrafluoro· e t.hyle ne (T eflon) and graphite·polyte traflu oroethyle ne mixtures. Mass s pectrometri c ex amination of the produ ct gases show ed C F" to be the only maj or produc t with C" F6(g) prese nt in only very s mall a mount s . Th e co mpl e te ness of co mbu sti on of th e graphit e wa s de termin ed by c he mi cal analysis of co mbu stion res idu es and found to ra nge from 97 to be tte r than 99 perce nt. Fro m th e co mbu stion data, th e hea ts of form ati on ~H;l>I8 [ CF4(g)] and ~H;,,,~[ C"F4 (solid polym e r)] we re de te rmined to be -222.87 ± 0.38 kcal mol -I and -197.82 ± 0.39 kcal (gfw C2F.) -I , respectively. Th e un certainties are estimates of the ove raU experimental e rrors .A previously re port.ed value for the heat of formati on of AlF3(c) is adju sted to be co ns iste nt. with t.h e presen t work. An e valu ation of oth er data on CF 4 is prese nted. Th e heat of formation of CF.(g) is co mbined with other wo rk to de rive the heats of formation of HF soluti ons a t three s pecific con· ce ntrati ons.Key Words : Alum inum fluorid e, c arbon te trafluorid e . flu orine, fluorin e bomb calorim e try, graph ite , heat of co mbusti on, heat of form a tion, hydroge n flu oride aqueous, T efl on.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.