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Difficulty: MediumAnalyzing Experimental Procedures and Apparatus

Experiment 1
Students constructed a Soxhlet extraction apparatus to isolate lipids from an algal biomass sample using an organic solvent. The apparatus consists of a boiling flask on a heating mantle, a thimble chamber containing the solid algal sample, an outer vapor tube, a side-arm siphon tube, and a water-cooled reflux condenser mounted at the top.

During operation, solvent boiled in the flask rises as vapor, condenses, and continuously washes over the solid sample inside the extraction chamber until a siphon cycle is triggered.

Match each apparatus component below with its primary procedural function in the extraction process.

  • Water-cooled Reflux CondenserCooled by circulating water to convert vaporized solvent back into liquid droplets that drip onto the sample
  • Siphon Tube Side ArmAutomatically drains accumulated liquid from the extraction chamber back into the boiling vessel once the liquid level reaches the siphon crest
  • Porous Cellulose ThimbleHolds the solid biomass sample while allowing liquid solvent and dissolved solute to pass into the extraction chamber
  • Boiling FlaskContinuously reheats the accumulated lipid-rich solution to generate fresh, solute-free solvent vapor

Answer

Water-cooled Reflux Condenser matches with converting vaporized solvent back into liquid droplets; Siphon Tube Side Arm matches with automatically draining liquid once the liquid level reaches the siphon crest; Porous Cellulose Thimble matches with holding the solid biomass while letting liquid pass through; Boiling Flask matches with continuously reheating the solution to generate fresh solvent vapor.
Each component performs a specific mechanical or thermal function essential to continuous extraction: the condenser cools solvent vapor into liquid drops; the thimble acts as a permeable container for the solid sample; the siphon tube drains the liquid chamber periodically when full; and the boiling flask vaporizes clean solvent while concentrating non-volatile lipids.

Step-by-Step Solution

1
Analyze the physical pathway of the solvent vapor.
Solvent vapor travels up through the vapor tube to the top where it encounters the cold inner wall of the reflux condenser, turning back into liquid drops.
Condensation requires heat removal, which is provided by cooling water circulating in the condenser jacket.
2
Identify the role of the thimble inside the extraction chamber.
The thimble contains the solid algal biomass so particles do not clog the narrow siphon tube, but its permeable walls allow liquid solvent to soak and dissolve lipids.
Physical filtration inside the chamber isolates the solid matrix from the liquid extract.
3
Analyze the fluid dynamics of the siphon tube.
As condensed solvent fills the extraction chamber, liquid rises in the siphon arm until reaching the top curve, triggering siphon flow that empties the chamber into the lower flask.
This automated dumping step resets the chamber for the next cycle of extraction.
4
Determine the function of the boiling flask.
The flask acts as the heat reservoir where pure solvent vaporizes leaving behind the non-volatile extracted lipids.
The difference in boiling points allows solvent recycling while concentrating extracted product in the bottom vessel.

Key Concept

Function and operational sequence of laboratory apparatus components in a continuous extraction system
Estimated Time:1m 30s
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Topics

Analyzing Experimental Procedures and Apparatus

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