5

• What is the first step in preparing cyclohexene?

  Pour 20 cm​3​ of cyclohexanol into a flask
• Why is it important to record the mass of cyclohexanol accurately?

  To ensure precision in the experiment
• What should you do after adding phosphoric acid to the flask?

  Shake continuously
• What is the purpose of adding anti-bumping granules to the flask?

  To prevent vigorous boiling and large bubbles
• What temperature should the distillation process be conducted below?

  100 °C
• Why can cyclohexene be separated during distillation?

  It has a lower boiling point than cyclohexanol
• What is added to the distillate in the separating funnel?

  50 cm of saturated sodium chloride solution
• What role does saturated sodium chloride solution play in the distillation process?

  It acts as a drying agent
• What should you do after separating the two layers in the funnel?

  Run off the lower layer into a beaker
• What is the purpose of adding anhydrous calcium chloride to the crude cyclohexene?

  To remove water from the product
• What should be done after adding calcium chloride to the flask?

  Stopper the flask and shake the contents
• How do you calculate the mass of dry cyclohexene produced?

  Reweigh the container after decanting
• What test confirms the presence of an alkene in the distillate?

  Using Bromine water
• What color change indicates the presence of an alkene with Bromine water?

  Goes colorless
• What is the first step in preparing ethanal?

  Dissolve potassium dichromate (VI) in dilute sulfuric acid
• How much potassium dichromate(VI) should be used per 10 cm​3​ of dilute acid?

  Approximately 1 g
• Why should the boiling tube be cooled in water?

  To avoid loss of volatile ethanal
• How should ethanol be added to the oxidising agent?

  Dropwise using a teat pipette
• What is the purpose of anti-bumping granules in the boiling tube?

  To allow more even heating of the mixture
• How should the boiling tube be positioned during heating?

  Clamp it at about 45 degrees
• What should be done after heating the beaker of water?

  Distill off approximately 5 cm3 of liquid
• What does Tollen’s reagent test for?

  Presence of ethanal
• What observation indicates a positive result for ethanal using Tollen’s reagent?

  A silver mirror should form
• What safety precaution should be taken with Tollen’s reagent?

  Dispose of it thoroughly with water
• What should be done with glassware that contained Tollen’s reagent?

  Rinse with dilute sulfuric acid