Practicals

• What does distillation do?

  separates liquids with different boiling points
• What does a separating funnel do?

  Separates water form organic liquids after distillation
• What does drying do?

  Remove traces of water
• Name 2 drying agents

  MgSo4

  CaSo4
• What does redistillation do?

  Used to separate 2 organic liquids with the same/ similar boiling points
• What is filtration?


  the process that separates a solid from the liquid
• What does recrystallization do?

  Used to purify solid product after filtration
• How do you separate an organic liquid?

  Distillation then separating funnel then drying then redistillation
• How do you separate a solid?

  Filtration then recrystallisation then filtration
• What does condensation equipment do in reflux?

  It stops organic vapour from escaping by condensing it back to liquid
• How is vapour converted to liquid in reflux?

  The vapour rises up the inner tube until it meets the outer jacket containing cold water so the vapour condense and drips back into the flask
• Why is reflux used?

  It is used as heating under reflux enables a liquid to be continually boiled whilst the reaction occurs and it also prevents volatile Components from escaping and stops the flak boiling dry
• Why are anti-bumping granules used in reflux?

  As they ensure small bubbles arise and prevents vigorous uneven boiling
• Why is grease applied in reflux?

  A think grease layer is applied to the ground glass joint to ensure a good seal
• How do you clamp the condenser in reflux?

  Loosely as it is fragile
• Why should the condenser never have a stopper?

  If it did it would create a closer system and pressure would build up inside as the heated air expands
• Where does water enter in reflux?

  Water enters from the bottom and leaves at the top to ensure the jacket is full
• How do you connect the rubber tubing to the reflux equipment?

  Rubber tube is used to connect the inlet of the condenser to the tap and the outlet to the sink
• Where should water enter in distillation?

  From the bottom to endure sufficient cooling
• What equipment is used in distillation?

  Pear shaped flask

  Condenser

  Rubber tubing

  Heat source

  Clamp stand

  Screw tap adaptor

  Receiver adaptor

  Still head

  Thermometer
• How does distillation work?

  -The different liquids in the mixture will have different boiling points.

  
  

  -The liquid with the lowest boiling point is the most volatile and will boil first.

  
  

  -The vapour moves out of the flask up into the other parts of the apparatus, leaving behind the less volatile components of the mixture.

  
  

  -When the vapours reach the cold condenser, they condense and become a liquid.

  
  

  -This liquid then drips into the collecting flask.
• How do you identify organic products after distillation?

  When preparing samples of organic liquid water may be obtained along side

  This will bring about the appearance of two liquid layers

  One will be organic one and one will be the aqueous one

  To identify which one is which you add some water to the mixture the larger that increases in size is the aqueous layer
• How do you separate organic layers and aqueous layers?

  Ensure tap of separating funnel is closed

  Pour liquid mixture in separating funnel and place a stopper on the top of the funnel and invert the contents

  Add water to see which layer gets bigger and this one is the aqueous layer

  Place a conical flask under the separating funnel, remove stopper and open tap until the whole of the lower layer has left the funnel

  Place a second conical flask under the separating funnel to collect the other layer

  The layers are now separated in the flasks

  Label which is which
• Why is titration used?

  Used to find a solution of unknown concentration by reacting it with another solution of known concentration
• What are the steps of a titration?

  Fill a burette with the acid of known concentration. Accurately measure an amount of the alkali using a calibrated pipette and pipette filler. Add the alkali to a conical flask with a few drops of a suitable indicator. Run in acid from the burette until the colour just changes showing that the solution in the conical flask is now neutral. Repeat the procedure adding the acid dropwise.
• How can you remove acid impurities?

  add aqueous sodium carbonate

  shake

  acid will react and release CO2

  add solution to separating funnel

  slowly open tap whilst holding separating funnel upside down

  remove aqueous sodium carbonate layer

  wash organic layer and run into a flask
• What are the results of using phenolphthalein

  Alkali turns pink

  Acid turns colourless
• What are the results of using methyl orange?

  Alkali turns yellow

  Acid turns orange

  End point turns orange
• Draw reflux apparatus.


  Include:

  
  

  - Liebig condenser.

  - COLD water in (bottom right).

  - COLD water out (top left)

  - Pear-shaped flask.

  - Anti-bumping granules.

  - Open top.

  - HEAT.

  
• Draw the gas collection apparatus?

  
• Draw the titration equipment (1)

  
• Draw the titration equipment (2)

  
• Draw the gas syringe equipment

  
• Draw the distillation equipment (1)

  
• Draw the distillation equipment (2)

  
• Draw the filtration equipment

  
• How do you calculate percentage error for equipment?

  error given x amount of time equipment used / measurement for apparatus
• How do you calculate maximum percentage error?

  add all the individual equipment errors
• Give 2 ways in which you can reduce error in titrations

  replace measuring cylinders with pipettes/ burettes as they are more precise

  to reduce burette reading errors make the titre a larger volume
• give 2 ways in which you can make burette titre a larger volume

  increase the volume and concentration of substance in conical flask

  decrease the concentration of substance in burette