Chemistry Gcse Ocr C1

Front 1

Give four types of additives and why they are added to food

Back 1

1) Food colours make food appetizing
2) Flavour enhancers bring out the taste and smell

3) Antioxidants help preserve food
4) Emulsifiers help oil and water blend

Front 2

What is an emulsion

Back 2

Lots of droplets of one liquid suspended in another liquid

Front 3

What is an emulsifier

Back 3

Something that stops two liquids from seperating

Front 4

Give three examples of food which contain emulsifiers

Back 4

1) Mayonnaise
2) Low-fat spread
3) Ice cream

Front 5

Explain the structure of an emulsifier molecule

Back 5

1) Hydrophilic head that bonds to water molecules and repels oil molecules
2) Hydrophobic tail that bonds to oil molecules and repels water molecules

Front 6

Explain how the emulsifier molecule works

Back 6

Shake oil and water with emulsifier

Oil forms droplets
Emulsifier molecules latch onto droplets with hydrophobic tail
Hydrophillic head faces outwards, repelling other oil molecules, whilst latching onto water molecules
Emulsion doesn't separate out

Front 7

Give four reasons as to why food is cooked

Back 7

1) Better taste and texture
2) Easier to digest when cooked
3) High temperature kill disease-causing microbes
4) Some food is poisonous when raw and the poison must be killed with high temperature

Front 8

What type of change is cooking

Back 8

A chemical change (thermal decomposition)
It is irreversible

Front 9

What happens when eggs and meat are cooked

Back 9

Eggs and meat have protein
Protein molecules in food are heated, breaking their chemical bonds.
Protein molecule takes a different shape (denatures)
Gives the food a more edible texture

Front 10

What happens when potatoes are cooked

Back 10

Potato cells have a rigid cell wall of cellulose
Cellulose cannot be digested by humans
Cooking potato ruptures cell walls
Also makes starch grains swell up and spread out
These make potato softer, more flexible and easier to digest.

Front 11

What is thermal decomposition

Back 11

When a substance breaks down into simpler substances when heated

Front 12

What is the thermal decomposition of Sodium Hydrogencarbonate (Baking Powder)

Back 12

Sodium hydrogencarbonate -> sodium carbonate + carbon dioxide + water

2NaHCO₃ -> Na₂CO₃ + CO₂ + H₂O

Front 13

What is baking powder used in

Back 13

Baking cakes, CO₂ produced makes cakes rise

Front 14

What is the chemical test for Carbon Dioxide

Back 14

Bubble gas produced through limewater
Limewater will turn cloudy if CO₂ is present

Front 15

What is an ester

Back 15

An ester is a chemical that smells nice
They are found in nature in fruits and apples
And are used in perfumes, flavourings and solvents

Front 16

Equation for the production of an ester (esterification)

Back 16

Carboxylic Acid + Alcohol -> Ester + Water

Front 17

What is the method for producing an ester?

Back 17

Mix 10cm^3 of a carboxylic acid (ethanoic acid) with 10cm^3 of an alcohol (ethanol).
Add 1cm^3 of concentrated sulphuric acid to the mixture (catalyst)
Warm gently for 5 minutes (as it is flammable)
Pour mixture into 150cm^3 of sodium carbonate solution to neutralize the acids

Front 18

Properties needed by perfumes

Back 18

1) Easily evaporates - need to smell it
2) Non-toxic - cannot harm the user
3) Doesn't react with water - sweat contains water
4) Doesn't irritate the skin - couldn't be used on the neck/wrists and could harm user
5) Insoluble in water - shouldn't wash off everytime you get wet e.g. sweat/wash hands

Front 19

For and against testing perfumes on animals

Back 19

1) Need to check if they're safe for humans, could harm them.
2) Animal cruelty, wrong to cause suffering of animals for testing cosmetic goods. Banned in the EU

Front 20

What is volatility

Back 20

How easily a liquid evaporates

Front 21

What is evaporation

Back 21

When fast moving particles at the surface of a liquid overcome the forces of attraction to the other particles and turn into a gas

Front 22

What is a solution

Back 22

A mixture of a solute and solvent that does not separate out

Front 23

What is a solute

Back 23

Substance being dissolved

Front 24

What is a solvent

Back 24

Liquid it is dissolving into

Front 25

What does soluble mean

Back 25

Dissolvable

Front 26

What does insoluble mean

Back 26

Not dissolvable

Front 27

What does solubility mean

Back 27

A measure of how much something will dissolve

Front 28

Why doesn't nail varnish dissolve in water

Back 28

Molecules of nail varnish are more attracted to each other than to water
Molecules of water are more attracted to each other than to nail varnish
Because the molecules are more attracted to themselves, they cannot form a solution

Front 29

Why does nail varnish dissolve in acetone (nail varnish remover)

Back 29

Molecules of nail varnish are more attracted to acetone than to each other
Molecules of acetone are more attracted to nail varnish than to each other
Because the molecules are more attracted to each other, they form a solution.

Front 30

What does the solubility of a substance depend on

Back 30

The solvent used

Front 31

What three substances does paint contain

Back 31

1) Solvent
2) Binding Medium
3) Pigment