oChem Lab Notes SIMPLE DISTILLATION Distillation boiling a liquid and condensing the vapor A method of separating liquids The type of data we would collect for simple distillation 01 29 2015 A temperature Y vs volume X graph Can be used to separate two different liquids only if the boiling points of the two liquids differ by 40 C If not 40 difference in boiling points Then do it by a series of simple distillations o We start with 100 mL and collect every 25 mL o We take the first 25 mL and collect every 5 mL o Then we take that 5 mL and collect every 1 mL o We keep doing this until we collect a drop of pure lower boiling point liquid The better way do it is called fractional distillation The only difference between the apparatus is there is a tube FRACTIONAL DISTILLATION between the head How does putting a piece of glass allow us to separate these things o It is cooler up there the temperature difference All it is a series of simple distillations but it all takes place inside the column of glass OUR EXPERIMENT 30 mL of an unknown Two questions o Identity of the two unknowns o Ratio Hot plate sitting on top of lab jack Place the 30 mL into the round bottom flask STIR BAR IS VERY IMPORTANT o stirs solution to insure even heating We use aluminum heating bar We re going use rubber and glass thermometer adapter o bottom of the therm has to be just even or slightly below the distillation head Place condenser in the stir bar WATER PRESSURE NEVER NEEDS TO BE HIGH o Nice slow trickle slowly turn on the water The receiving flask will be three 15 mL falcon tubes labeled A B C o Have them labeled and ready to go Wherever you have a glass joint but those little blue clasps Make sure you have the orientation set up properly depending on where you are in relative to the hood Do we turn our hotplate on NO o Ask your TA to double check that everything is okay first Gas chromatography Mobile phase nonpolar Stationary phase polar These two phases have a difference in polarity like attracts like The plateaus are boiling points By the end of class you need to have your fractions in your falcon tubes if you can t get your GC runs you can do it during period three DO NOT THROW YOUR SAMPLES AWAY Put a cap back in your falcon tubes wrap it up with parafilm and put it in your drawer On the webpage there are links to help explain distillation and gas chromotography 01 29 2015 01 29 2015