Unit 2: Soaps Flashcards
How are soaps formed
Alkaline hydrolysis (breaking up) of fats and oils by sodium or potassium hydroxide by boiling under reflux conditions
Step 1 of making soap
Hydrolysis produces three fatty acid molecules and one glycerol molecule
Step 2 of making soap
Fatty acid molecules neutralised by the alkali, forming water soluble, ionic salts called soaps
Why use soap
Water on non-polar substances like grease due to fats, do not dissolve in water. Water is polar, grease is non polar
How soaps work step 1
Hydrophobic non-polar tail dissolves into droplets of oil and grease
How soaps work step 2
Negative ionic hydrophilic heads remain in surrounding water
How soaps work step
Agitation causes ball-like structures called micelles to form
How soaps work step 3
Negatively-charged ball-like structures repel each other and oil or grease is kept suspended in water stopping the grease from forming back together
Soapless detergents
When soap is used in hard water, charged calcium and magnesium ions present react with soap to form the insoluble substance scum.
Soapless detergents
Non-polar hydrophobic and ionic hydrophilic heads, remove oil in the same way as soap