Chemistry 2

An acid is a substance with a pH of less than 7. 

A base is a substance with a pH of greater than 7

An alkali is a base that is soluable in water. 

Neutralisation = acid + base = salt + water 

•Acid + alkali = salt + water

•Acid + metal =  salt + hydrogen

•Acid + carbonate = salt + carbon dioxide + water

Fertilisers provide plants with essential elements for growth. 

Fertilisers replace the missing elements or provide more of them. This helps to increase the crop yield as the crops can grow faster and bigger. 

Eutrophication can be caused. This is the excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life. 

Precentage yield compares actual with predicted yield.

The mass of product that you end up with is called the yield of reaction. 

The haber process is a reversible reaction. 

Inductrial condition: 

Pressure: 200 atmospheres       Temperature: 450 degress C       Catalyst :Iron

The iron catalyst speeds up the reaction and keeps the costs down, which it gets to the equilibrium proportions more quickly. 

Production cost:

• Price of energy
• Cost of raw materials
• Rate of prouduction
• Labour Costs 

Optimum conditions are those that give the lowest production cost.  

Salt is mined from underneath Cheshire. 

It can be mined by pumping hot water underground. 

An alloy is a mixture of a metal and other elements. 

Brass - Copper and Zinc E.g. Musical Instruments

Bronze - Copper and Tin E.g. Bells

Solder - Lead and Tin E.g. Solder

Amalgam - Mercury E.g. Densitry

Iron + oxygen + water = Hydrated Iron oxide

Aluminium advantages: lower density and aluminium corrodes less. 

Steel - Bodywork                                                   Fibres - Seats and Floors 

Aluminium - Parts of engine

Plastics - Wires and doors

Alfred Wegner hypothesised that africa and south america had previously been one continent which had been split. 

Wegners theory wasn't accepted because it wasn't convincing and they couldn't explain the 'land bridge' theory. 

Then the evidence is overwhelming because

• Magma rises up through the sea floor, solidifies and forms underwater mountains that are roughly symmetrical. 
• new sea floor has been created and continents were moving apart 
• Scientists had collected information to support wegner's theory. 

Volcanoes are formed by molten rock. 

Oceanic and continental crust colliding causes volcanoes. The crust at the ocean floor is denser than the crust below the continents. 

As the oceanic crust is forced down it melts and starts to rise. If thos molten rock finds its way to the surface, volcanoes form. 

Volcanic activity forms from igneous rocks. Igneous rocks is made when any sort of molten rock cools down and solidifies. 

The type of igneous rock depends on how quickly the magma cools and the composition of the magma. 

The three steps in the formation of sedimentary rock:

1) They are formed from layers of sediment

2) Over millions of years the layers get buried and the weight squeezes out the water

3) Fluids deposit natural mineral cement. 

Limeston is an example. 

Metamorphic rocks are formed from other rocks and marble is an example of this. 

Igneous rocks are formed from fresh magma. E.g. Granite

Reinforced concrete is a composite material-its a combination of concrete and solid steel support. 

Quarrying ususes up the land and can cause visual pollution. 

However, it can provide jobs. 

The earth has a crust, mantle or core. The lithosphere includes the crust and upper part of the mantle. 

Radioactive Decay creates a lot of the heat inside the earth. This heat creates convection currents in the mantle, which causes the plates of the lithosphere to move. 

Tectonic plates are like big rocky rafts and the plates move at 2.5cm per year. 

Volcanoes and earthquakes often occur where the plates meet. Its the movement of plates against each other.