Other slides in this set

Slide 2

Preview of page 2

Here's a taster:

Additives make food last longer
· Food colours ­ make the food look more appetising
· Flavour enhancers ­ bring out the taste and smell of food without adding a flavour
of their own
· Antioxidants ­ help to preserve food Hydrophilic
(likes water, hates oil)
(likes oil, hates water)
Emulsifiers help oil and water mix(emulsion)
When you add some emulsifier to oil and water, the oil forms droplets surrounded by
a coating of the emulsifier with the hydrophilic part facing outwards. Other oil
droplets get repelled by the hydrophilic part of the emulsifier whilst any water
molecules latch on so the emulsion doesn't separate out.
Key Words:
Solution: a mixture of its solute and solvent that does not separate out
Solute: the substance being dissolved
Solvent: the liquid it's dissolving in
Soluble: it will dissolve
Insoluble: it won't dissolve
Solubility: a measure of how much will dissolve…read more

Slide 3

Preview of page 3

Here's a taster:

Cooking and Chemical Change
Some foods need to be cooked e.g. boiling, grilling, frying etc...
1) Better taste/texture
2) Easier to digest
3) Harmful microbes are killed (from high temperatures)
4) Some foods such as kidney beans contain poison when raw
Cooking can cause chemical changes;
e.g. Eggs and meat ­ good sources of protein, protein molecules change shape when heated.
The energy from cooking breaks some of the chemical bonds in the protein allowing the
molecule to take a different shape. The food also gets a more edible texture. This change is
irreversible and is called denaturing.
e.g. Potatoes ­ potatoes are plants meaning each potato is surrounded by a rigid cell wall made
of cellulose. Humans cannot digest cellulose. Cooking the potato ruptures the cell walls. It
makes the starch grains inside the cell swell up and spread out. These changes make the
potato softer and more flexible and also much easier to digest.
2NAHCO NaCO + CO + HO…read more

Slide 4

Preview of page 4

Here's a taster:

Esters are made by etherification:
Acid + Alcohol = Ester + Water
Perfumes need certain properties...
Easily Evaporates ­ So the perfume particles can reach the nose
Non- Toxic ­ so it doesn't poison you
Doesn't react with water ­ so it doesn't react with the water in your sweat
Doesn't irritate the skin ­ so you don't get a rash/burn
Insoluble in water ­ so it doesn't wash off every time you get wet
to make an ester...
Mix 10cm³ of a carboxylic acid e.g. ethanoic acid with 10cm³ of an
alcohol such as ethanol. Add 1cm³ of concentrated sulphuric acid to this
mixture, warm gently for about 5 minutes. Add the mixture to 150cm³ of
sodium carbonate solution(to neutralise the acids) and smell carefully. A
fruity smell should be the result.…read more

Slide 5

Preview of page 5

Here's a taster:

Kinetic Theory ­ Forces between Particles
Solids: strong forces of attraction between the particles. If you heat the solid and give
the particles more energy eventually it will melt and become a liquid
Liquids: some forces of attraction between the particles. If you heat the liquid
eventually it will boil and become a gas
Gases: no forces of attraction between the particles. The hotter the gas gets the faster
they move, it expands when heated or the pressure increases.
Perfumes need to be quite volatile so they can evaporate enough to be smelt. The
particles in the perfume have very weak forces of attraction between them
meaning its easy for the particles to overcome this force and escape. You only need
a little heat energy (body temperature) to make the perfume evaporate.…read more

Slide 6

Preview of page 6

Here's a taster:

Nail varnish is insoluble in water..
The molecules of nail varnish are strongly attracted to each other. The
attraction is stronger than the attraction between the nail varnish
molecules and the water molecules
The molecules of water are strongly attracted to each other. This
attraction is stronger than the attraction between the water
molecules and the nail varnish molecules.
Nail varnish is soluble in acetone(nail varnish remover) ...
The attraction between the acetone molecules and the nail varnish
molecules is stronger than the attractions holding the two substances
together.…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9

Slide 10

Preview of page 10
Preview of page 10


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »