Practicals

Question 1

What is the annotated setup for reflux?

Answer 1

Question 2

What does heating under reflux do?

Answer 2

• Allows for full reaction without loss of reactants, products or solvents

Question 3

What are the steps in heating under reflux?

Answer 3

1. REaction mixture placed into a pear shaped flask
2. Antibumping granules are added to promote smooth boiling
3. Flask is placed in water bath
4. Water passes through the condenser to condence any gasous products after being heated

Question 4

What is the setup for solvent extaction using a separting funnel?

Answer 4

Question 5

What are the requirements for solvent extraction using a seperating funnel?

Answer 5

• Organic reactions must be neutralised
• Add NaCO3

Question 6

What are the steps in solvent extraction?

Answer 6

1. Contents of reaction vessle are transfered into a seperating funnel
2. Funnel inverted
3. Two layers seperate and then form
4. Remove the stopper and remove the less dense later

Question 7

How do you extract a solvent using drying agents?

Answer 7

• Drying agents remove traces of water from an organic product
• Ahnhydrous organic salts - calcium chloride

Question 8

What are the steps in using drying agents in solvent extraction?

Answer 8

1. Spatula drying agent into organic product and swirled (lid added on low bpt)
2. If dying agent clumps together there is still water in the product
3. More is added until some is dispersed in the organic liquid as fine powder
4. Which is then decanted or filtered which leaves a clear organic liquid

Question 9

WHat is crystalisation used for?

Answer 9

• Used for purifying impire solids
• Hot solvent is used to dissolve organic solid and impirties
• Where the solid crystalises leaving impuritied in solution
• Minimum amount of solvent to dissolve solid means prevention of loss of product
• Hot filtration remove solid impurities

Question 10

What are the steps in recrystallisation?

Answer 10

Question 11

What is the setup for distiliation?

Answer 11

Question 12

What is Distilation?

Answer 12

• Used in a reacion that doesnt go to completion OR unwanted chemicals are produced
• Seperated compounds by boiling point

Question 13

What are the steps in distilation?

Answer 13

1. Anti-bumping granules added to promote smooth boiling
2. REaction heating using a mantle
3. Distalte forms and drips into receiving vessle after bign condenced

Question 14

What is boiling point determination?

Answer 14

• Determined by distilation
• Gently heated until it boils and temp recorded
• IF the sample contains impurities boiling temp may appear higher than pre-exsisting data or boil over a range of tempratures?

Question 15

What is melting point determination?

Answer 15

• purity of a compound can be determined by measuring the mtp
• add a sample of the solid product into a capillary tube and place into the heating element of the mtp apparatus
• slowly increase the temp until the substance starts to melt
• there is a temp range from when the solid just started to melt to when it fully melts
• compare the mtp against data book value
• if substance contains impurities the mtp will be lower and the temp range the substance melts at will be larger

Question 16

What is the setup for steam ditilation?

Answer 16

Question 17

What is steam distilation?

Answer 17

• used when we want to separate substances with high bpts or decompose when heated
• if the product is immiscible with water then steam distillation is used to separate compounds that couldn’t be done under standard conditions

Question 18

What are the steps in steam distilation?

Answer 18

1. Pushed through impure sample
2. Steam lowers bpt of the immiscible product and allows for it to be distilled out of the mixture before it decomposes
3. More volitile chemical in the mixture will evaporate first
4. Product condensed and collected in a separate flask
5. Separated using a separating funnel (if product is partially miscible then you have to use solvent extraction)