Chemistry

Chemistry

1. Iron - displacement, blast furnace Copper - smelting, phytomining, bioleaching, electrolosis

   • Electrolysis is used to remove the impurities from copper that has been produced by extraction
     • + = anode - = cathode
       • The anode is impure and the cathode is a pure copper. The electrolyte is copper sulfate solution. During electrolysis, a current passes through the completed circuit. The anode is made of impure copper, which is sometimes called blister copper. During electrolysis, the anode gets smaller. This happens because the anode is dissolving.
         • Carbon dioxide has been increasing due to combustion of wood and fossil fuels as they release CO2 into the air. The CO2 is then taken in by the plants due to photosynthesis taken up by the trees because they remove CO2. The animals then eat the plants and it enters the food chain however CO2 is given off the animals by respiration by breathing. The animals and plants die causing them to decay and release CO2 from the bacteria however these can be burned into fossil fuels which put the CO2. The carbon dioxide has increased because we are burning more fossil fuels for energy and there is less trees to absorb the carbon dioxide therefore the amount is higher and there is a growth in population so there is a higher demand of food meaning they can't respire.
           • C16H34 -> C8H16 + C8H18 The chemical equation for the formula of hexadecane is C16H34. This is then split or broken into 2 parts. From C16H34 you get C8H16 which is a alkene, you also get one alkane C8H18. Cracking is good because you get shorter hydrocarbon chains which are all mostly alkenes. Alkenes are highly useful as they can be turned into polymers as plastics. The shorter the hydrocarbons chain, the easier it is to burn and it will come off the fraction earlier and this will more likely make different products.
       • At the anode (the positive electrode) oxidisation as electrons (negative) are lost as copper dissolves and loses mass. Cu - 2e = Cu2+
       • At the cathode (the negative electrode) you get reduction as electrons (negative charge) are gained as the copper gains more mass. Cu2+ + 2e- = Cu
         • O - oxidisation I - is L - loss R - reduction I - is G - gained

2. Corrosion is the gradual destruction of a metal due to reactions with other chemicals in its environment. Over time, corrosion changes the appearance of a metal as it breaks down and it becomes weaker. Corrosion can seriously damage metallic objects and structures. Coating the surface of a metal with paint and certain chemicals can protect it.

   • Metals behave differently when exposed to the environment. Gold is an unreactive metal and does not corrode. In many cultures, gold is considered a precious metal and is used to make sacred and decrotive objects. Items made from gold can survive for thousands of years and have even been found in good condition underwater.
     • Rusting is a chemical reaction between iron, oxygen and water.
       • iron + oxygen + water = hydrated iron (III) oxide
   • Aliminuim is very reactive but does not erode.
     • The outer aliminium atoms react with oxygen in the atmosphere. This forms a thin layer of aliminuim oxide on the metal's surface, which protects the metal from corrosion.

3. N2(g) + 3H2(g) = 2NH3(g)

   • Ammonia : - important material used in fertilisers - ammonia is a vital route by which nitrogen in the air can be made avaliable to plants to enable them to build protein molecules - plants need nitrogen compounds, dissolved in water, which they absorb by roots. - without ammonia based fertilisers, the world would be unable to grow enough food to feed the population.
     • A high pressure catalyst of iron and temperature of 450 degrees is used to make the reaction of hydrogen and nitrogen which then makes ammonia.
     • Exothermic - lowering the temperature increases this reaction (makes more ammonia)
       • Endothermic - raising the temperature increases the reaction ( making less ammonia)

4. The atmosphere today is kept in balance by living things. The nitrogen and carbon cycle keep the amount of nitrogen gas, oxygen gas and carbon dioxide gas control

   • Composition of dry air -Nitrogen 78% - Oxygen 21% - Argon 1% - Carbon Dioxide 0.05%