Chemistry

20. Synthesis of a solid organic product

  • 00:30 What is the role of phosphoric acid?
  • 00:39 How do you know the solid has dissolved?
  • 00:52 Why is the beaker placed in an ice bath?
  • 01:11 Why use a minimum amount of ethanol? 
  • 01:17 Why use warm ethanol?  
  • 01:36 Where are the impurities at this stage?
  • 01:54 How can you assess whether your sample is pure?

  • de-ionised water

  • digital balance (pref. 3-decimal place, minimum 2-d.p)

  • 25 cm3 pear-shaped flask

  • 10 cm3 measuring cylinder

  • hot water-bath

  • ice-bath

  • glass stirring rod

  • Buchner funnel & suction apparatus

  • watch glass

  • sample vial

  • labels / fine-tipped permanent marker

  • filter paper

  • melting-point apparatus / Thiele tube

  • capillary tube

Hazard Risk Control measure

2-hydroxybenzenecarboxylic acid (white solid) – moderate health hazard, corrosive.

Contact with eyes.
Ingestion.

Eye: flood with tap water (10min)

Ethanoic anhydride (CH3CO)2O – flammable, moderate health hazard, corrosive.

Contact with eyes.
Inhalation.

Eye: flood with tap water (10min). See doctor. Lungs: fresh air. See doctor.

Concentrated H3PO4 solution –
corrosive

Contact with skin or eyes

Eye: flood with tap water (10min). See doctor. Skin: use dry cloth to remove excess. Drench with water.