Making soaps in the laboratory... (1 Viewer)

[leehuan]

We used reflux.

1. Literally no other source I know of used reflux. Is it necessary to reflux? And..
2. Even if it's not necessary it's still suitable right?

 

[Crisium]

We used reflux.

1. Literally no other source I know of used reflux. Is it necessary to reflux? And..
2. Even if it's not necessary it's still suitable right?

What vapours are there to condense LOL

I wouldn't recommend writing it down as your method, it's more commonly associated with esterification and you may give the marker the impression that you mixed up your practicals here's what I did (From my notes):

5.1 Saponification

Aim: To make soap from a vegetable oil and compare the properties of the product with a commercially produced soap.

Equipment:

• 8 ml Vegetable Oil (e.g. Olive Oil, Caster Oil, etc.)

• 25 ml 50% (v/v) Ethanol-Water Mixture

• 150 ml Saturated Sodium Chloride Solution

• 2.5 g Sodium Hydroxide

• 0.1 mol L-1 Calcium Chloride Solution

• 10 ml Measuring Cylinder and 100 ml Measuring Cylinder

• Electronic Balance

• Stirring Rod

• Universal Indicator Paper

• Paper Towel

• Small Amount of Bath Soap, Liquid Soap and Detergent

• 4 x Test Tubes With Rubber Stoppers and a Test Tube Rack

• 50 ml Beaker and 150 ml Beaker

• 2 x 250 ml Beakers With Beaker Tongs

Method:

Part A - Making Soap:

1) Set up a hot plate.

2) Pour 6 ml of vegetable oil into a 150 ml beaker.

3) Weigh out 2.5 g of sodium hydroxide in a 50 ml beaker and add 20 ml of the ethanol-water mixture, stirring to dissolve. The ethanol does not take part in the reaction but assists the reaction between the oil and sodium hydroxide.

4) Slowly add the sodium hydroxide solution to the vegetable oil, stirring continuously during the addition.

5) Place the beaker containing the reaction mixture on the hot plate and boil gently, stirring frequently. If the beaker is overheated the mixture may spit out of the beaker. Therefore it is essential to keep your face away from the beaker and make sure it is stirred frequently to prevent spattering. Alternatively, the temperature can be momentarily lowered.

6) After approximately 15 minutes of heating and stirring the oil should be dissolved, and the mixture should look thick and creamy.

7) Add 25 ml water to the hot solution and stir.

8) Pour this mixture into a 250 ml beaker containing 150 ml saturated sodium chloride solution and stir. Allow this mixture to cool.

9) Remove the soap layer and place it in a 50 ml beaker. Rinse this beaker a couple of times with distilled water to remove any excess sodium hydroxide.

10) Place the rinsed soap on some paper towel to dry.

Part B – Testing Soap:

1) Place a small amount of the soap you have just made in a test tube. In separate test tubes place the same amount of bath soap, liquid soap and liquid detergent.

2) Add 3 – 5 ml of distilled water to each test tube, stopper and then shake vigorously. Record any observations.

3) Determine the pH of each of the solutions using universal indicator or pH paper.

4) Add 4 - 5 drops of vegetable oil to each of the solutions, stopper and shake. Observe how well the oil is emulsified in each.

5) Repeat Steps 1 and 2 using 3 - 5 ml calcium chloride solution instead of distilled water to stimulate hard water, as the addition of calcium chloride will increase the concentration of calcium ions in the solution.

6) Observe any difference between the solutions formed.

Safety:

Wear safety goggles and protective clothing. Sodium hydroxide (i.e. Caustic Soda.) is very corrosive so avoid contact with eyes or skin. If contact occurs wash with plenty of water for 10 – 15 minutes. Ethanol is highly flammable so keep away it away from naked flames. The soap you produce should not be used on people or animals because it may still contain caustic soda.

If you haven't heard of the term lather before it's the same as sudsing (iirc) and the results just compared them qualitatively by seeing how far the bubbles went.

 

[leehuan]

Sent from my iPhone using Tapatalk

 

[leehuan]

Testing soap was on another sheet for me.
_____________________________________
I also have this from the notes I use... (Copy and pasted so you can guess where the notes came from based off format)

4.5.4 Describe the conditions under which saponification can be performed in theschool laboratory and compare these with industrial preparation of soap
In the school laboratory, esters are boiled in a solution of sodium hydroxide to produce a homogenousmixture. Given the volatility of the substances being handled- in particular the ester- this processmust take place in reflux. Given that alkanoic acids have higher melting and boiling points thantheir alkanol counterparts- a characteristic attributable to the stronger dispersion forces of a longercarbon chain- several options are then possible:
•
If the carboxylate ion has more than four carbon atoms, its solubility is likely to be relativelylow. As such, it may be precipitated out in its acidic form upon being acidified, and thenfiltered off.
•
If the carboxylate ion has an extremely low degree of solubility, it may simply be removed uponbeing cooled with ice.
•
If the carboxylate ion has a boiling point which is relatively different, distillation may be usedto separate the components.The key characteristics of this process are:
•
A water bath and hotplate are used.
•
The full reaction can be brought about within an hour.
•
Refluxing is employed.
•
The product is relatively impure, with quantities of sodium hydroxide present.
•
Process is dependent upon different boiling and melting points.

 

[Mr_Kap]

Testing soap was on another sheet for me.
_____________________________________
I also have this from the notes I use... (Copy and pasted so you can guess where the notes came from based off format)

4.5.4 Describe the conditions under which saponification can be performed in theschool laboratory and compare these with industrial preparation of soap
In the school laboratory, esters are boiled in a solution of sodium hydroxide to produce a homogenousmixture. Given the volatility of the substances being handled- in particular the ester- this processmust take place in reflux. Given that alkanoic acids have higher melting and boiling points thantheir alkanol counterparts- a characteristic attributable to the stronger dispersion forces of a longercarbon chain- several options are then possible:
•
If the carboxylate ion has more than four carbon atoms, its solubility is likely to be relativelylow. As such, it may be precipitated out in its acidic form upon being acidified, and thenfiltered off.
•
If the carboxylate ion has an extremely low degree of solubility, it may simply be removed uponbeing cooled with ice.
•
If the carboxylate ion has a boiling point which is relatively different, distillation may be usedto separate the components.The key characteristics of this process are:
•
A water bath and hotplate are used.
•
The full reaction can be brought about within an hour.
•
Refluxing is employed.
•
The product is relatively impure, with quantities of sodium hydroxide present.
•
Process is dependent upon different boiling and melting points.

just use what roland smith says in his worksheets..


ill email it to you if you dont have his worksheets for industrial...just pm me your email

 

[Crisium]

All of the websites I come across seem to say that its necessary to distil and remove fat droplets to complete the process and this also indicates when the process is complete