UCSB CHEM 6AL FINAL EXAM 2026-2027
QUESTIONS AND ANSWERS GRADED A+
A compound with high IMF will have a ____ BP than a compound with low IMF;
Imagine a solution of water boiling in a round flask. the vapors above this liquid
are ______ the liquid themselves.
higher; the same temp as
T or F: higher vp means that a liquid is harder to turn into a vapor
F its easier!
T or F: molecules with lower IMF exert lower vapor pressures
F they prodcuce higher VPs!
T or F: compounds with a high vp have a low bp
T :)
How does the vapor composition compare to the liquid composition in a 50:50 mix
of two liquids?
,if we have pentane and hexane, vapor would not be 50:50, it would be more
pentane because pentane has lower BP.
temperature composition diagram
simple vs fractional distillation
simple: used to purify almost already pure compounds, to separate liquid from
solid impurities, and to remove volatile (readily evaporating) solvents. few cycles,
heat source to heat liquid. have boiling stones in liquid. vapors travel up and
condense back down into different tube. works well if there is a large difference in
BP (60-70 degrees C). only does one evaporation/ condenstion cycle). how can we
improve this? by using more theoretical plates (each TP represents one
evap/conden cycle). do this by using fractional distillation
fractional distillation: fractionating columns increase TPs. allows for greater
separation, very important globally.
efficiency: fractional has better separation, but a little bit of liquid doesnt vaporize
and yield decreases due to more cycles needed.
, azeotropes
a mixture of two liquids that has a constant boiling point and composition
throughout distillation. IMF determine differences in BP. no longer acts as an ideal
solution. when the liquid comp=vapor comp. example is water and ethanol.
what is the highest % of alcohol achievable by distillation?
95-96%. dont drink 200 proof alcohol (100% EtOH)!!!
chromatography
Separation of complex mixtures of compounds based on their polarity and
distribution between a solid phase and a mobile phase
what are the (sub)types of chromatography?
1. Liquid Chromatography (LC): Column Chromatography and Thin-Layer
Chromatography (TLC: A micro version of liquid column chromatography)
2. High Pressure LC (HPLC)
3. Gas Chromatography (GC)
mobile vs solid phase: definition and how column chromatography works
mobile: Liquid or gas that carries compounds through
the solid phase. AKA the solvent or the eluent
solid: A stationary composite through which the
QUESTIONS AND ANSWERS GRADED A+
A compound with high IMF will have a ____ BP than a compound with low IMF;
Imagine a solution of water boiling in a round flask. the vapors above this liquid
are ______ the liquid themselves.
higher; the same temp as
T or F: higher vp means that a liquid is harder to turn into a vapor
F its easier!
T or F: molecules with lower IMF exert lower vapor pressures
F they prodcuce higher VPs!
T or F: compounds with a high vp have a low bp
T :)
How does the vapor composition compare to the liquid composition in a 50:50 mix
of two liquids?
,if we have pentane and hexane, vapor would not be 50:50, it would be more
pentane because pentane has lower BP.
temperature composition diagram
simple vs fractional distillation
simple: used to purify almost already pure compounds, to separate liquid from
solid impurities, and to remove volatile (readily evaporating) solvents. few cycles,
heat source to heat liquid. have boiling stones in liquid. vapors travel up and
condense back down into different tube. works well if there is a large difference in
BP (60-70 degrees C). only does one evaporation/ condenstion cycle). how can we
improve this? by using more theoretical plates (each TP represents one
evap/conden cycle). do this by using fractional distillation
fractional distillation: fractionating columns increase TPs. allows for greater
separation, very important globally.
efficiency: fractional has better separation, but a little bit of liquid doesnt vaporize
and yield decreases due to more cycles needed.
, azeotropes
a mixture of two liquids that has a constant boiling point and composition
throughout distillation. IMF determine differences in BP. no longer acts as an ideal
solution. when the liquid comp=vapor comp. example is water and ethanol.
what is the highest % of alcohol achievable by distillation?
95-96%. dont drink 200 proof alcohol (100% EtOH)!!!
chromatography
Separation of complex mixtures of compounds based on their polarity and
distribution between a solid phase and a mobile phase
what are the (sub)types of chromatography?
1. Liquid Chromatography (LC): Column Chromatography and Thin-Layer
Chromatography (TLC: A micro version of liquid column chromatography)
2. High Pressure LC (HPLC)
3. Gas Chromatography (GC)
mobile vs solid phase: definition and how column chromatography works
mobile: Liquid or gas that carries compounds through
the solid phase. AKA the solvent or the eluent
solid: A stationary composite through which the
