Page:Outlines of Physical Chemistry - 1899.djvu/168

 ��OUTLINES OF PHYSICAL CHEMISTRY

��Heats of Formation (in Large Calories) — continued

�� � �Gaseous

�Liquid

�Solid

�Dis- solved

�(Si, F 4 ). .

� � � �(SiF 4, 2HF, aq)

�(Sn, cy.

�(Sn, Cl 4 ).

�C, Cl 4 ) ..

�from diamond.

� � �c, o, eg

� � � �(Sb 2, S,).

� �(B„ S,). .

�from amorphous B

� �(Si, S 2 ). .

�from crystallised Si

� �(C, S 2 ). .

�from diamond.

� � �C 2, N 2 ) ..

�id.

�-

�(C, N, H). .

�•

�(C, N, H, 0).

�(cyanic acid).

�0, N, K, 0) . |

�(C, N, K, S). |

��The numbers in this table have been obtained by various investigators, and are taken from Berthelot's ' Donn6es et lois num^riques ' (1897).

For certain very important substances, /. Thomsen has found heats of formation which do not quite agree with those given by BertheloL According to Thomsen :

(H 2, 0) = 68-36 Cal. (for liquid water at 18°)

(C, 0) = 29-0 Cal. x mm. Q ,. . lM

)n r\ \ qa-qa p ft i (* or amorphous carbon, at lo J.

We may further quote some interesting data relating to water :

��Molecular specific heat :

from -20 to 0° (ice)

to 100° (water) at 15° 130 to 230° (steam) Molecular heat of fusion at 0°

Molecular heat of vaporisation at 0°

at 15° 100° 194°

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1-43 Cal.

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