Natures Chemistry Flashcards
(33 cards)
What is an addition reaction?
When 2 molecules combine to form a single molecule?
What is oxidation and reduction for carbon compounds?
> Oxidation is an increase in the oxygen to hydrogen ratio
>Reduction is a decrease in the oxygen to hydrogen ratio
How are emulsifiers made and used in food?
They are made by reacting edible oils with glycerol.
in the molecules formed only 1 or 2 fatty acid groups are linked to each glycerol backbone. Hydroxyl group is hydrophilic, hydroxyl groups dissolve in water. Fatty acid chains are hydrophobic and dissolve in oil. hydroxyl groups dissolve in water. this forms a stable emulsion.
What is an emulsion?
An emulsion contains small drops of one liquid dispersed in another liquid.
What happens in a condensation reaction?
2 molecules are joined together with the elimination of a small molecule.
When an ester link is formed, the small molecule that is eliminated is water.
How are esters formed?
They are formed by condensation reactions between an alcohol and a carboxylic acid.
alcohol + carboxylic acid = ester + water
this is known as esterification.
What is an ester?
A molecule containing an ester link ( O=C-O)
What does the oxidation of food cause?
The oxidation of edible oils gives foods a rancid flavour.
Oxygen from the air causes the oxidation of food.
What bases can carboxylic acid react with to produce salt + water (+ co2) ?
a metal oxide + CA = a salt + h2o
a metal hydroxide + CA = a salt + h2o
a metal carbonate + CA = a salt + h2o + co2
What does a COOH group on a molecule mean?
That it is a carboxylic acid.
The COOH group is called a carboxyl
What does an OH group on a molecule mean?
That it is an alcohol.
an OH group is called a hydroxyl.
What is an alcohol group containing 3 hydroxyl groups called?
Triol
What is an emulsifier used for?
An emulsifier can e used to prevent non polar and polar liquids from separating into layers.
(think mayo)
Describe how detergents work.
it has a non polar hydrophobic tail and a polar hydrophilic head.
It removes oil and grease in the same way as soap but doesn’t form scum when used in hard water.
What is an alcohol containing 2 OH groups called?
Diol
What are antioxidants and what do they do?
They are molecules that prevent unwanted oxidation reactions from occurring.
They are substances that are easily oxidised, and oxidise in place of the compounds they have been added to protect.
What is the difference between primary, secondary and tertiary alcohols?
Primary: The carbon the OH group is attached to is only joined to 1 other carbon.
Secondary: Joined to 2 other carbons
Tertiary: Joined to 3 other carbons
What is a fatty acid?
Fatty acids are saturated or unsaturated straight chain carboxylic acids containing even numbers of carbon atoms ranging from C4-C24 (Primarily C16 + C18)
When are fats and oils produced?
When an alcohol and glycerol condense with a carboxylic acid (Fatty acid)
Glycerol (Propane 1,2,3 triol) is a tryhydric alcohol)
Why are fats and oils needed in the body?
> Highly concentrated source of energy (more than carbohydrates)
Essential for transport of fat soluble vitamins
What happens if an ester is hydrolysed?
An alcohol and carboxylic acid are produced
Are many flavour and aroma molecules aldehydes or ketones?
Aldehydes
Explain how soaps work.
Soap molecules have a Polar hydrophilic heads and a non polar hydrophobic tail. Soaps are ionic and water soluble.
Hydrophobic head is attracted to the water and the tail is attracted to the oil.
oil and grease are held inside a ball and suspended in water.
How can you differentiate between an aldehyde and a ketone?
Aldehydes can be further oxidised to a carboxylic acid.
an aldehyde but not a ketone will cause:
>Blue Fehlings solution to form a brick red precipitate
>Colourless Tollens reagent to form a silver mirror
>Orange acidified dichromate to turn green
