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p-DCB is produced by chlorination of benzene using ferric chloride as a catalyst: . C 6 H 6 + 2 Cl 2 → C 6 H 4 Cl 2 + 2 HCl. The chief impurity is the 1,2 isomer.The compound can be purified by fractional crystallization, taking advantage of its relatively high melting point of 53.5 °C; the isomeric dichlorobenzenes and chlorobenzene melt well below room temperature.
Boiling point (°C) K b (°C⋅kg/mol) Freezing point (°C) K f (°C⋅kg/mol) Data source; Aniline: 184.3 3.69 –5.96 –5.87 K b & K f [1] Lauric acid: 298.9 44 ...
There are three distinct chemical compounds which are dichlorobenzenes: . 1,2-Dichlorobenzene or ortho-dichlorobenzene;; 1,3-Dichlorobenzene or meta-dichlorobenzene;; 1,4-Dichlorobenzene or para-dichlorobenzene.
The term "cryoscopy" means "freezing measurement" in Greek. Freezing point depression is a colligative property, so ΔT depends only on the number of solute particles dissolved, not the nature of those particles. Cryoscopy is related to ebullioscopy, which determines the same value from the ebullioscopic constant (of boiling point elevation).
Older mothballs consisted primarily of naphthalene, but due to naphthalene's flammability, many modern mothball formulations instead use 1,4-dichlorobenzene.The latter formulation may be somewhat less flammable, although both chemicals have the same NFPA 704 rating for flammability.
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A bath of ice and water will maintain a temperature 0 °C, since the melting point of water is 0 °C. However, adding a salt such as sodium chloride will lower the temperature through the property of freezing-point depression. Although the exact temperature can be hard to control, the weight ratio of salt to ice influences the temperature:
The extent of freezing point depression observed in DESs is well illustrated by a mixture of choline chloride and urea in a 1:2 mole ratio. Choline chloride and urea are both solids at room temperature with melting points of 302 °C (decomposition point) and 133 °C respectively, yet the combination of the two in a 1:2 molar ratio forms a ...