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This technique is used when the boiling point of the desired compound is difficult to achieve or will cause the compound to decompose. [1] Reduced pressures decrease the boiling point of compounds. The reduction in boiling point can be calculated using a temperature-pressure nomograph using the Clausius–Clapeyron relation. [2]
The normal boiling point is the boiling point at atmospheric pressure, but it can also be reported at higher and lower ... initial alcohol mixture to a temperature ...
This reduces the boiling point of the liquid to be evaporated, thereby reducing or eliminating the need for heat in both the boiling and condensation processes. There are other advantages, such as the ability to distill liquids with high boiling points and avoiding decomposition of substances that are heat sensitive.
A liquid in a partial vacuum, i.e., under a lower pressure, has a lower boiling point than when that liquid is at atmospheric pressure. Because of this, water boils at 100°C (or with scientific precision: 99.97 °C (211.95 °F)) under standard pressure at sea level, but at 93.4 °C (200.1 °F) at 1,905 metres (6,250 ft) [ 3 ] altitude.
Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon hexane, and 34.6 °C for diethyl ether.
This Wikipedia page provides a comprehensive list of boiling and freezing points for various solvents.
In that context, a lighter component means a component with a lower boiling point (or a higher vapor pressure) and a heavier component means a component with a higher boiling point (or a lower vapor pressure). Thus, for the distillation of any multi-component mixture, the relative volatility is often defined as
If the azeotrope can be "jumped over", distillation can continue, although because the activity coefficients have crossed, the component which is boiling will change. For instance, in a distillation of ethanol and water, water will boil out of the remaining ethanol, rather than the ethanol out of the water as at lower concentrations.