Distillation Flashcards
Vapor Pressure
the pressure that a vapor/gas exerts on its surroundings while in thermodynamic equilibrium with its liquid state at a given temperature.
Definition of Distillation?
Distillation is the act of separating substances and/or components from a liquid mixture using differences in boiling point and condensation
Volatility
a measure of how easily a liquid will move into a vapor state.
Generally speaking, higher volatility compounds have LOWER boiling points (and vice versa)
What are the four things that are needed for distillation?
1) a heat source
2) a vessel for the liquid to be distilled
3) a way for vapors to reach the receiving vessel
4) a cooling medium to condense the vapors back into liquid
Azeotropes
An azeotrope is a constant boiling mixture where the composition of the vapor is the same as the liquid being distilled. Once we’ve received the azeotrope, we cannot separate the individual components of a mixture through normal distillation practices.
What are factors that can increase the amount of reflux inside the still?
-distillation speed
-cleanliness of surfaces inside and outside the still
-the charge volume inside the still
-the addition of rectification equipment such as columns, trays and purifiers
-still geometry
-the temperature of the air surrounding the still
What are the four primary functions of a distillation tray?
1) Provide a surface for the mixing of vapor and liquid for proper heat exchange between the two.
2) Provide a space for the liquid and vapor to separate after heat transfer has occurred.
3) Provide a route for high volatility vapors to rise above the plate and continue through the still.
4) provide a route for liquid and low volatility compounds to fall below the plate and lower back into the still.
What are the four primary reasons for the use of copper in distillation?
1) Copper is more malleable and easier to work with than many other metals, including stainless steel,
2) Copper is a good conductor of heat,
3) Copper catalyzes many positive flavor reactions during distillation,
4) Copper reacts with several sulfur-containing compounds and removes them during distillation.
What are the sulfur compounds that copper reacts with and removes?
-Hydrogen Sulfide (H2S)
-Dimethyl Sulfide (DMS)
-Dimethyl Tridulfide (DMTS)
What are high volatility compounds with lower boiling points (heads/foreshots)?
-Methanol
-Acetaldehyde
-Ethyl Acetate
+more
What are low volatility compounds with higher boiling points (tails/feints)?
-Phenols
-fusel oils/higher alcohols
-fatty acids
-water
+more
What are the sensory implications of Methanol (heads)?
Similar to the sweet aroma of ethanol, but a bit sharper and more pungent.
In a batch distillation process you will never have methanol by itself.
What are the sensory implications of ethanol?
Ethanol is not actually orderless. It is slightly sweet and lightly fruity.
What are the sensory implications of ethyl acetate?
-in low amounts it can lend subtle fruitiness to spirit,
-but in high amounts it is incredibly pungent and solventy
What are the sensory implications of Isoamyl acetate?
-In low amounts it produces pleasant banana-like aroma in distillate,
What are the sensory implications of Acetaldehyde?
-generally highly volatile and usually not much of an issue in properly produced spirits,
-in low concentrations it has green apple aromas
What are the sensory implications of Diacetyl?
Butter & Butterscotch
