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

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��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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