Oil

Oil — liquid from light brown (almost colourless) till dark-brown (almost black) color (though there are samples even of emerald-green oil). The average molecular weight of 220 — 300 g/mol (it is rare 450 — 470). Density 0,65 — 1,05 (usually 0,82 — 0,95) / см�; oil which density lower than 0,83, is called easy, 0,831 — 0,860 — average, higher than 0,860 — heavy. Oil density, as well as other hydrocarbons, strongly depends on temperature and pressure. It contains a large number of different organic substances and therefore it is characterized not by the temperature of boiling, but temperature of the beginning of boiling of liquid hydrocarbons (usually> 28 �C, ≥100 �C in case of heavy are more rare than nefty) and fractional structure — an exit of the separate fractions which are overtaken at first with an atmospheric pressure and then under vacuum in certain temperature limits, as a rule to 450 — 500 �C (80% of volume of test boil away ~), 560 — 580 �C (90 — 95%) are more rare. Crystallization temperature from −60 to + 30 �C; depends mainly on the content in paraffin oil (than its more, that temperature of crystallization is higher) and easy fractions (the their more, the this temperature is lower).