Heating Under Reflux Flashcards
What is the purpose of heating organic reactions?
To overcome activation energy and increase the rate of reaction
Many organic reactions occur slowly at room temperature.
What is heating under reflux?
A procedure used to prepare an organic liquid without boiling off the solvent, reactants, or products
It allows a reaction to be carried out at a fixed temperature.
List the apparatus needed for heating under reflux.
- round-bottom or pear-shaped flask
- condenser
- rubber tubing
- stand and clamp
- heat source
Common heat sources include Bunsen burner, tripod, gauze, or heating mantle.
What is the role of anti-bumping granules in a reflux setup?
To ensure the contents boil smoothly
Without them, large bubbles can form and cause the glassware to vibrate or jump.
What should be done before fitting the condenser in a reflux apparatus?
Add the reaction mixture and anti-bumping granules to the flask
This is important for a smooth boiling process.
Why is a heating mantle preferred for flammable liquids?
It eliminates the presence of a naked flame for added safety
This is important in case of leaks or cracks in the apparatus.
What is the correct way to position the condenser during reflux?
Keep the condenser in the upright position
This ensures proper functioning and safety.
True or False: You should put a stopper in the top of the condenser.
False
A closed system would result in pressure build-up, risking explosion.
How should water flow in the condenser?
Water enters at the bottom and leaves at the top
This ensures that the outer jacket is full.
What happens to the vapor in a reflux setup?
It rises up the inner tube of the condenser, condenses, and drips back into the flask
This process prevents volatile components from escaping.
Fill in the blank: Heating under reflux allows a liquid to be continually _______ while the reaction takes place.
[boiled]
This prevents the flask from boiling dry.
What is the analogy used to describe the process of reflux?
Similar to putting a lid on a saucepan when cooking
This analogy helps visualize how vapor condenses and returns to the flask.
What should be applied to the ground-glass joint on the condenser?
A thin layer of grease
This helps create a good seal and allows easy disassembly after the experiment.
What is a common heat source used in reflux experiments?
Bunsen burner
Other options include a tripod, gauze, or heating mantle.
Why should condensers be clamped loosely?
The glass outer jacket is very fragile and easily broken
Proper handling is essential for safety.
