U3 - Cleaning materials Flashcards
Def: Hydrophillic
substance that mixes with water or dissolves in water
Describe the structure of the soap molecule
- head contains O2 atoms and is polar, mixes with water, hydrophillic
- tail contains C and H atoms and is non-polar, dissolves in oil droplets, hydrophobic
Def: Emulsifying agent
substance soluble in water and fat and enables fat to be dispersed in the water
Def: Emulsion
mixture of 2 liq that are not usually able to mix
Def: Emulsifier
substance that stabilizes an emulsion
How does soap act as an emulsifying agent
it enables fat to be uniformly dispersed in water as an emulsion. soap causes fat and water to mix easily. when fat mixed with water solution, soap molecules squeeze between water molecules and fat molecules. soap acts as an emulsifier.
How are substances able to mix
Substances will only mix if they have similar structures and bonding
Can sugar and salt dissolve in petrol
sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.
Can sugar and salt dissolve in petrol
sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.
Can sugar and salt dissolve in petrol
sugar is a molecular solid, and will dissolve in petrol that is a molecular liquid. Salt is an ionic solid, and will not dissolve in petrol.
Describe the structure of a soap (detergent) molecules
soap has hydrocarbon tail that mixes with oils and fats and is hydrophobic. the head is the ionic part that dissolves in water and is hydrophillic. The head therefore easily mixes with water, while the tail part easily mixes with oils and fats
Def: Surfactants
substances that reduce the surface tension of a liquid when it is dissolved in water, soap is a surfactant
Explain how surfactants work
hydrophobic chain is forced out of the water in between the water molecules, while the ionic head remains in the water.
How is soap made
made from fat or oil (plant or animal) together with an alkali.
How are detergents made
made from crude oil sources together with and alkali
Is soap biodegradable or non-biodegradable
biodegradable
Is detergents biodegradable or non-biodegradable
non-biodegradable
What are the effects of non-biodegradable detergents
should be avoided because they are persistant, and can influence the environment negatively. Cause pollution
Advantages of the use of soap and detergents
- Remove fat an oil from clothes
- Soap makes water “wetter
- Prevent the formation of “scum” when used in hard water
Disadvantages of the use of soap and detergents
- Non-biodegradable detergents cause environmental pollution
- Scum on the surface of the water affects clothes
How are soaps prepared
are prepared by the hydrolysis of fats or oils. The fat/oil is hydrolysed, by adding sodium hydroxide to the fat.
Def: Hydrolysis
breaking down a compound by a chemical reaction with water.
Preparation of soaps
- heat some oil / fats
- add some methanol and mix well
- add concentrated sodium hydroxide
- warm gently until thick
- heat salt solution till boiling point and add to soap mixture
- heat strongly to evaporate off liquid, pour into molds + allow to cool
What is the formula for the preparation of soap
fat + sodium hydroxide — soap + glycerol
