C6 - Fats, Oils, Emulsions and Soap Flashcards
What are the states of fats and oils at room temperature?
• fats are solid at room temperature
• oils are liquid at room temperature
What are some uses of oils?
- Vegetable oils are an important part of a healthy diet
- also important raw materials for the chemical industry
- Biodiesel is an alternative to diesel made from crude oil and is a renewable resource.
- Soap is also made from vegetable oils.
How do you make an ester? Uses?
when a carboxylic acid reacts with an alcohol. Some esters are used in perfumes and as solvents. These are simple esters like ethyl ethanoate, made from ethanoic acid and ethanol.
What are fats and oils made of?
fatty acids chemically joined to glycerol, which is an alcohol. Fatty acids have long chains of carbon atoms. Glycerol has three hydroxyl groups, –OH, unlike many other alcohols that only have one.
What is the difference between saturated and unsaturated fats and oils?
• in a saturated fat or oil, all the carbon-carbon bonds in the fatty acid parts are single covalent bonds
• in an unsaturated fat or oil, one or more of the carbon-carbon bonds in the fatty acid parts is a double covalent bond.
General : how does bromine water show unsaturation?
• bromine water stays orange when mixed with a sample of a saturated alkene, fat, or oil
• bromine water goes colourless when mixed with enough unsaturated alkene, fat, or oil.
Detail : how does the bromine test work?
Bromine reacts with the carbon-carbon double bonds in unsaturated fats and oils. An addition reaction happens there, producing a dibromo compound that is colourless. Saturated fats and oils do not contain carbon-carbon double bonds, so they cannot react with bromine to produce a colourless compound.
Why are saturated fats unhealthy and unsaturated fats healthy?
- Saturated fats can raise the level of cholesterol in the blood. High levels of cholesterol increase the risk of blocked arteries and heart disease.
- Unsaturated fats and oils tend to be more healthy choices. For example, omega-3 oils from oily sh such as mackerel are thought to help reduce the risk of heart disease.
Define the term immiscible and emulsion.
- Two liquids that do not dissolve into one another.
- If vigorously shaken together, they form a mixture called an emulsion. Tiny droplets of one of the liquids are dispersed throughout the other liquid. Will separate out again if there is no emulsifier.
What are the two types of emulsion? Give an example for each.
• oil-in-water = tiny droplets of oil dispersed in water
• water-in-oil = tiny droplets of water dispersed in oil.
Milk = oil-in-water emulsion. It contains tiny droplets of butterfat dispersed throughout a watery liquid.
Butter = water-in-oil emulsion. It contains tiny droplets of watery liquid dispersed throughout the butterfat.
What type of emulsion is margarine? How is it made?
- Margarine is a water-in-oil emulsion.
- It consists of a blend of different vegetable oils, mixed with water.
- It is important that margarine from the refrigerator is soft enough to spread easily on bread and toast, but not be so soft that it runs everywhere.
- Unsaturated vegetable oils tend to have relatively low melting points, so they must be blended with saturated vegetable oils to achieve the desired consistency.
( Margarine ) How are unsaturated oils turned into saturated oils?
By reacting them with hydrogen. The hydrogen reacts at the carbon-carbon double bonds, turning them into single bonds.
How is soap made? What is the process called? Give a word equation.
When oils or fats react with hot sodium hydroxide solution. The reaction splits the oil into glycerol, and sodium salts of the fatty acids. These sodium salts are the soap. This process of splitting up natural fats and oils using sodium hydroxide solution is called saponification.
fat + sodium hydroxide → soap + glycerol
Explain what type of reaction saponification is an example of.
A hydrolysis reaction. This where a compound is broken down by its reaction with water. During saponification, the hydroxide ions from the sodium hydroxide solution break down the oil or fat molecule in a similar way to a water molecule. They cause the bonds between the fatty acids and glycerol to break.
