Chemistry Unit 1 for AQA Higher

The Earth is made up of about 78% Nitrogen, 21% Oxygen, 0.9% Argon (a noble gas) and about 0.038% Carbon Dioxide and the rest is other gases like water vapour. 

The Earth is made up of the Crust, the Mantle, the Outer and the Inner Core. 

The crust is only a few kilometers thick and is made up of tectonic plates. 

Tectonic plates move very slowly and when the collide, they send massive vibrations up through the crust and cause massive devistation the countries lying on the tectonic plates. These are called earthquakes. If the tectonic plates collide in the sea, they can cause Tsunami's which are just as devistating. 

Noble Gases include: Helium, Argon, Neon and Xenon. All noble gases are monatomic. This means they exist as single atoms.

Helium is denser than air and is used in balloons. Argon is used in lightbulbs because it doesn't react with the filament. Neon glows when electricity is passed through it. 

Fuel from oil is made from hydrocarbons. Hydrocarbons react with oxygen. With a good air supply, complete combustion gives the equation:

Hydrocarbon + Oxygen -----> Water + Carbon dioxide

Incomplete combustion produces Carbon Monoxide, a poisonous gas, Carbon, seen as soot or smoke, and Sulphur Dioxide, also poisonous. All the above are harmful to the environment. Car fuel is made of hydrocarbons. Cars can never completely break down the hydrocarbons so it still releases some carbon monoxide and some sulphur dioxide.

Large hydrocarbons can be broken down into smaller, useful hydrocarbons. This happens by a process called cracking. 

There are two types of fuels called Alkanes and Alkenes. Alkenes are unsaturated because they have double bonds and can take part in chemical reactions that alkanes cannot. Alkenes have the general formula of CnH2n. Alkanes are saturated because they have single bonds. They have a general formula CnH2n+2.

Vegetable oils are found in seeds, nuts and some fruits. They can be extracted by crushing the material to make oil. This is how olive oil is made. Some oils are more difficult to extract, like sunflower oil. This has to be dissolved in solvent to get the oil.

Vegetable oils are made up of glycerol and fatty acids. The fatty acid is to stop the oil from dissolving in water. 

Saturated fats are usually solid at room temperature. Unsaturated fats are usually liquid at room temperature. To make a fat unsaturated, it must go through a process called hydrogenation. This involves heating the saturated fat at 60° with a catalyst. The double bonds become single bonds and hydrogen atoms fill the gaps.

All additives that are approved for use in foods in the UK have what is called an   E-number. For example, E102, Tartrazine. This adds the orange colour in fizzy drinks and curry foods.

E322, Lecithin is used as an emulsifier, to mix oil and water together in foods like Mayonnaise and Ice cream. These foods are emulsions.

E915, Aspartame is used as a sweetener in many foods like Cola, Yoghurt and Lager. 

A few years ago, a food colouring powder dyes called Sudan dyes crept into some foods. Sudan dyes are not approved for use in the EU as they are classed as genotoxic and/or carcinogenic by the European Food Safety Authority. The food it appeared in was immediately removed from shelves and destroyed. 

We extract metals that are more reactive than carbon, by electrolysis. These metals include metal oxides like copper oxide and magnesium oxide. Metals less reactive than carbon are extracted displacement. 

Iron is extracted in a blast furnace. Steel, an iron alloy is mostly iron 0.2 - 2.5% carbon and depending on its use, the rest is made up of manganese, chromium, nickel, titanium or cobalt. 

Stainless steel is mostly iron, 11% chromium or manganese, 2.5% carbon. It does not rust or corrode and is highly stain resistant. 

Brass is also an alloy. It contains copper and zinc, but can have up to 2% lead content. Bronze is another alloy. It contains copper and tin, however it does not necessarily contain tin, and can contain arsenic, phosphorus, aluminium, silicon or manganese instead.

Transition metals are in the middle of the periodic table and create coloured ions. They include titanium, nickel, iron and cobalt. They just like other metals in the sense that they are excellent conductors of heat and electricity. 

Polymers, like polythene, PVC and polypropylene are used to make many everyday items. They are all polymers.

Polythene is used to make plastic bags and bottles for water and fruit juices, shampoo bottles and other common household items. Polythene's primary use it packaging including plastic films and geomembranes. Polythene is the most demanded plastic.

Polypropylene is often used in packaging, common reusable containers like Tupperware and is used to make many textiles products like thermal underwear and fleeces, carpets and ropes. Polypropylene is the second most demanded plastic.

PVC or polyvinyl chloride is the third most used plastic. It is used in clothing (as a cheap leather rubber or latex substitute) upholstery, pipes, electrical cable insulation and inflatable items. 

Limestone is mostly calcium carbonate or CaCO . When it is heated, it breaks down to form calcium oxide and carbon dioxide. Calcium oxide reacts with water to form calcium hydroxide. Limestone is used to make mortar, cement, concrete and glass.

Calcium oxide is also known as quicklime. It is yellow when hot but white when cold. The reaction used to make quicklime is a thermal decomposition reaction.

Calcium hydroxide is also known as slaked lime. The reaction with water is exothermic and produces lots of heat. 

Glass is made from heating sand and soda then cooling. Cement is made with clay in a kiln. Concrete is mixed with sand, water and crushed rocks. Mortar is made from sand and water.