Application of precise heat-capacity data to the analysis of the temperature intervals of the NBS (1955) and the International Practical Temperature Scales in the region of 90 °K

Abstract

A method is presented for analyz in g t he te mperature in terva ls of the ~BS (1955) temperature scale a nd the International Practical Temperature Scale (IPTS) . Values of d1'/dR as a fun ction of resista nce a re d erived from equations of dQ / dR a nd dQ /dT, obtained from precise beat-capacity data (better t ha n ± 0.02 p ercent) by the method of lea st squa res .An adjusted t emperature scale is obtain ed by integration of the values of dT/dR relative to a referen ce t empera tu re a nd the corresponding resist a nce of the the rmometer. Th e res ults of the adjust ing process in thc neighborhood of the oxygen poin t (90.18 OK ) a re di scussed a nd compared with the exis t in g te mperature sca les . The derived te mperatu re scale was found to be s imila r to th e sca les ma inta in ed by the P ennsyl va ni a State Univers ity (PSU), t he Ph ysico-Techni ca l a nd Radio-Techn ical M eas ure ments Ins titute (PI1MI), a nd the 1\ationa l Physical La boratory (N PL) from th e upper limits of th ese scales, ncar 90 oK , down to 50 ole The a djustin g method prese nted is limi ted b y the uncerta inty of formul at ion of dQ/ dR a nd dQ /dT a nd the d erived te mperature scale is limited by t he accumu lated un certa inty in t he integral of dT/dR.

Critical analysis of the heat-capacity data of the literature and evaluation of thermodynamic properties of copper, silver, and gold from 0 to 300 oK

“…Heat-capacity determinations using resistance thermometry are dependent on the dR/dT or essentially the "size of the degree" of the temperature scale. Heat-capacity results, obtained using the NBS-1955 and the IPTS, exhibit reproducible anomalies as large as 0.2 percent that are attributable to deviations of these temperature scales from the thermodynamic scale [47]. Barber 273°K which is as closely related to the thermodynamic scale as the present knowledge permits [85,7].…”

Heat capacities and related thermal data for diethyl phthalate crystal, glass, and liquid to 360 K

“…The total weight of the loaded cell was about 390 g. Class S-2 calibrated weights designated NBS 3246 were used. The sample weight was adjusted for air buoyancy using 1.123 g/cm 3 as the density of diethyl phthal-) ate, 8.40 g/cm 3 as the density of the brass weights, and 0.00120 g/cm 3 as the density of air.…”

Heat capacity of liquid nitromethane from 35.deg. to 200.deg.C

“…For each determination on the empty calorimeter, the initial temperature, final temperature, and energy increment were fitted to a polynomial by the method of Furukawa and Reilly (5), in such a manner as to minimize the difference between Qobsd, the experimental energy increment, and Qcalcd, the energy increment calculated from the polynomial for the temperature range of the experiment. The resulting equation for the heat capacity of the empty calorimeter was Ce = 15.964705 + 6.207663 x 10% -5.965945 1 (1) where Ce is in joules per degree and t is in °C.…”