Accession Number:

AD0613403

Title:

THE HEAT CAPACITIES AND ENTROPIES OF SULFURIC ACID TRI-AND TETRAHYDRATES,

Descriptive Note:

Corporate Author:

CALIFORNIA UNIV BERKELEY LOW TEMPERATURE LAB

Personal Author(s):

Report Date:

1955-02-04

Pagination or Media Count:

6.0

Abstract:

The heat capacities of sulfuric acid tri- and tetrahydrates have been measured from 15 to 300K. The heats of fusion are 5736 and 7322 calmole at their respective melting points, 236.77 and 244.89K The peritectic temperature, where the trihydrate is in equilibrium with tetrahydrate and solution, was found to be 236.72K. The unstable melting point was estimated to be 0.05 above this temperature. The values of the entropies at 298.16K. are 82.55 caldeg. mole for the trihydrate and 99.07 caldeg. mole for the tetrahydrate. The entropies of formation of these two hydrates have been calculated from isothermal data and the values agree closely with those obtained by means of the third law of thermodynamics. This indicates that there is no residual disorder due to hydrogen bonding or other effects at limiting low temperatures. It has been shown that sulfuric acid tetrahydrate crystallizes as H2SO44.0000 0.0001H2O. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE