Chemistry 1 For Ethan And Maya

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Compounds (ionic)

Atoms join together to make compounds. Making bonds involves atoms giving away, taking or sharing electrons. A compound formed of a metal & non metal contains ions- the metal atoms lose electrons to form +ve ions and gain them to form -ve ions. They're strongly attracted to each other.

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Compounds (Covalent)

A compound formed of non metals consists of molecules. Each atom shares an electron with another atom. Each atom has to make enough covalent bonds to fill its outer shell.

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Formulas

CO2 is a compound formed from 1 carbon atom and 2 oxygen atoms. H2SO4 contains 2 hydrogen atoms, 1 sulphur atom and 4 oxygen atoms. Ca(OH)2 means everything in the bracket is multiplied by 2- there is 1 calcium atom, 2 oxygen atom and 2 hydrogen atom

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Using Limestone

Limestone is mainly calcium carbonate- CaCO3. When it is heated it thermally decomposes to make calcium oxide (CaO) and carbon dioxide (CO2).

When Magneesium ,Copper, Zinc and Sodium Carbonates are heated they do the same

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Using Limestone

Calcium Carbonate reacts with acid to make a calcium salt, carbon dioxide and water. The type of salt depends on the acid- reacting with Hydrochloric acid makes a chloride (CaCl2), or reacting with sulfuric acid makes a sulfate (CaSO4)

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Using Limestone

When you add water to Calcium Oxide you get Calcium Hydroxide ( Ca(OH)2 ). This is an alkali used to neutralize acidic soil. It's used in a test for CO2- you can make a solution of it in water (limewater) and bubble gas through it, it will turn cloudy if theres CO2 in the gas- as CaCO3 is formed

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Using Limestone

Quarrying makes holes that changes the landscape. It's noisy and dusty, and destroys habitats. Lorries cause noise and pollution. Cement factories make lots of dust, and energy is needed for this. But it can provide houses and roads, paints and medicines, neutralize sulfur dioxide, and creates jobs.

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Getting Metals From Rocks

Ores contain enough metal to make extraction worthwhile. Metals below carbon can be extracted chemically by reduction as carbon can take the oxygen away. Metals above carbon are electrolysised. It requires a liquid to conduct the electricity which has free ions.

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Getting Metals From Rocks

Copper can be extracted from a solution using a displacement reaction. A reactive metal in a solution of dissolved metal compound will replace the less reactive metal in the compound as the reactive metal bonds strongly to the non metal bit of the compound. Copper sulfate + iron --> Iron sulfate + copper.

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Properties Of Metals

Metals are strong, bendy and great conductors. Most elements are metals- only the ones on the far right of the table aren't. Copper is a good conductor, hard, and strong but can be bent. Aluminium is corrosion resistant and has a low density. Titanium has a low density and is very strong and corrosion resistant.

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Alloys

Pure iron is too bendy. From a blast furnace, 4% is impure iron, eg. carbon. Cast iron is too brittle. Pure iron has a regular arrangement of identical atoms which can slide over eachother making the iron soft and easily shaped. Iron is converted to steel- low carbon steel is easily shaped, high carbon is hard and inflexible, and stainless is corrosion resistant.

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Crude Oil

A mixture of hydrocarbons- not chemically bonded. Split into separate groups of hydrocarbons via a fractionating column. Heated oil is pumped at the bottom, then vaporized oil rises up and condenses at different levels. Longer chains at bottom, shorter at top.

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Crude Oil

It is mainly Akanes- CnH2n+2. The shorter the molecules the more runny, volatile (turn to gas at lower temp), and flammable they are.

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Crude Oil

Burns clearly, so make good fuels. Huge industry to find oil reserves. But crude oil might run out one day. Also, oil spills are bad and burning ooil can be bad.

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Environment
Burning fossil fuels releases gas and particles. Sulfur dioxide causes acid rain which can kill trees and damage limestone buildings. Partial combustion is when theres not enough O2 and soot and Carbon Monoxide is released.

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Environment

Climate change means the average temp of the earth increases. Particles cause global dimming. Fuels such as ethanol from fermentation of plants, biodisel from vegetable oils, and hydrogen gas are being used.

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Cracking Crude Oil

Cracking is the splitting up of long chain hydrocarbon to make shorter more useful things. It's a thermal decomposition reaction, done by heating the long chain to vaporize it, then passing it over an aluminium oxide catalyst at temps of 400-700 degrees. Products are alkanes and alkenes

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Alkenes and Ethanol

Alkenes have a C=C double bond. They are unsaturated because they can make more bonds if the double bond opens. CnH2n- Ethene= C2H4 and Propene= C3H6. Alkene test by adding it to bromine water- decolourises it.

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Alkenes and Ethanol

Ethene can be hydrated with steam in the resence of a catalyst to make ethanol. Ethanol can also be made by fermentation, sugar is converted to ethanol using yeast.

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Making Polymers

Alkenes can make polymers- its where you join monomers (small alkene molecules) together. Many ethene molecules make polyethene. A polymers properties are affected by temp and pressure. Lower temperature and high pressure= flexable and low density.

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Uses of Polymers

Light, stretchable polymers are used for plastic bags. Elastic polymers can make lycra, memory foam is a smart material, it gets softer as it gets warmer. Most polymers aren't biodegradable.

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Plant Oils

Some fruit and seeds contain lots of oil. These can be extracted for food or fuel. The plant material is crushed, then pressed. Oil can be separated from crushed plant using a centrifuge, or solvents can be used. Distillation refines oil.

Veg oils provide energy and nutrients and fatty acids.They have high boiling points and flavour. Rapeseed and soybean oil can be turned into fuels

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Plant Oils

Unsaturated oils contain double bonds. Oils and fats are long chain molecules with lots of carbon atoms. Unsaturated oils can be hydrogenated in a nickle catalyst at 60 degrees. It opens up the double bond. They have higher melting points and are solid at room temp.

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Emulsions

Oils mix with water to make an emulsion- droplets of the one are suspended in the other. Emulsions are thicker than oil or water. The more oil the thicker. Emulsifiers are molecules with one part attracted to water (hydrophilic) and one attracted to oil (hydrophobic). When shaken, the oil forms droplets surrounded by emulsifier with the hydrophillic bit facing outwards. Oil droplets are repelled by the hydrophillic bit, so it wont separate.

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Plate Tectonics

Wegener came up with the theory of continental drift after finding fossils of similar plants and animals on opposite sides of oceans. The exploitation was 'land bridges'. Wegener thought the continents were once linked then split. He found matching layers of rocks and noticed the jigsaw pattern. Ideas werent accepted as he thought it was caused by tidal forces and earths rotation- the forces needed would be impossible. He'd also used inaccurate data and made crazy predictions.

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The Earths Structure

The earth has a crust, mantle, outer and inner core. The crust is thin, the mantle is a solid that flows slowly where radioactive decacy takes place which produces heat causing convection currents that move plates. The core is made of iron and nickel. Tectonic plates can move suddenly to cause an earthquake or volcano at boundaries. They can't be predicted, but things like strain in rocks, or how molten rock rises into chambers causing the ground to bulge.

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The Evolution Of The Atmosphere

1: Volcanos gave out gases- the early atmosphere was mostly CO2, water vapour (condenses to form oceans), methane and ammonia.

2: Green plants and algae evolved and photosynthisesd to form oxygen. CO2 dissolved into oceans and Carbon in them became locked up.

3: The build up of Oxygen killed of early organisms but let more complex organisms evolve. The Ozone layer was created to block harmful rays from the sun

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Life and Change

Primordial soup- Lightning caused reactions between nitrogen, hydrogen, ammonia and methane, which made amino acids, which combined to form organic matter. Miller and Urey carried out an experiment to prove this theory , and found they were along the right track but not exactly right as only few acids were made.

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Fractional Distillation Of Air

Air is filtered to remove dust, and then cooled to -200 degrees to become a liquid. Water vapour is removed during cooling, and CO2 freezes and is removed. The liquified air is heated in a fractionating column and the remaining gases are seperated through fractional distillation.

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