Accession Number:

AD0019491

Title:

LOW TEMPERATURE HEAT CAPACITY AND THE SOLID I-SOLID II TRANSITION IN TETRANITRO-METHANE

Descriptive Note:

Technical rept. no. 5

Corporate Author:

OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS MCPHERSON CHEMICAL LAB

Personal Author(s):

Report Date:

1953-09-01

Pagination or Media Count:

17.0

Abstract:

Cooling-curve and heat measurements between liquid N and room temperatures were used in an investigation of the low-temperature heat capacity of CNO24. The cooling curve showed a break at 13.8 deg C, but the cooling persisted at a lower rate and temperature. A plot of the heat capacity as a function of temperature showed a first-order transition at -98.21 deg C. Incipient melting began at 233.2 deg K and ended at 13.0-13.8 deg C. Just above the transition temperature, the heat capacity of solid I was more than 8 caldegmol greater than that for solid II just below the transition point. As a result of the transformation from solid I to solid II, the entropy increased 2. 70 eu. In the solid I range, the heat capacity started to rise rapidly with increasing temperature, passed through an inflection, and then exhibited a marked premelting character. These observations suggested that additional modes of vibration become excited in solid I just above the transition temperature and that certain of these become translational modes after melting with the resultant decrease in heat capacity. CCl4 and CCH34 exhibited solid-solid transitions when their heat capacities were compared to that of CNO24. See also AD-19 459

Subject Categories:

  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE