Electrolysis Flashcards
(20 cards)
What are electrolytic cells? Describe set up of the electrolytic cell
Electrolytic cells are required to produce required substances. It involves an electrochemical cell involving two electrodes that are suspended in the same electrode solution. There is an electric potential difference, such as power source, battery or electric generator. There is the anode, cathode, electrotypes with ions, electric potential difference to maintain electric difference between two electrodes to allow for the flow of electrons in external circuit. The movement of the anions to the anode and cations to the cathode constitutes electric current in circuit.
Describe electrolytic cells function and what they depend on to function.
The power source is added to the electrolytic cell to drive the reaction of non-spontaneous redox reaction at the surface of the electrodes. The electrical energy can be converted to chemical energy in the reaction. The anode valence electron is removed, and the cathode is reduced. The reactions are dependent on composition of electrolyte and magnitude of current. I.e. molten salt is ionic compound that is molten, heat is required to keep it in molten form. The lead is formed from the reduction for molten lead 2 bromide. Lastly, electrically conductive (graphite) or inert metals are used as conductors.
Outline the desirable properties of metals namely, iron, aluminium, copper and zinc.
Metals are highly versatile with construction, electricity and transport applications. Metals include lead iron (steel production) aluminium (construction for low density vehicle) (copper electric application) zinc (galvanising).
Name the two forms of metals found naturally in the Environment
Metal presence of combined or uncombined metals is determined by the reactivity of the metals.
What are metals reactive with and where are they found naturally?
Most metals are reactive with oxides or sulphur or other materials. Thus, found in mineral form in body of rock called ore. Ores can contain one or more mineral they are to economically extract metals.
Describe the production process of metal. Include acronym.
Metal is then converted through a multistage process. Extraction involves removing mineral ore from crust. Concentration of metals is increased through removing impurities. Conversion are converted to a form that undergoes reduction. Metal is isolated using electricity or an appropriate reducing agent. Minor impurities are removed (by electrolysis) to increase the purity percentage of metals.
Zinc sulphide metal production example
Extraction and Concentration – Froth flotation
The minerals are extracted from the ore and are beaten down to increase the surface area of ore. The minerals are then used to remove the impurities then increase the w/w% of the minerals. Impurities removed by collectors, air and water. The collectors are negatively charged with xanate or dithiophosphate. The process then adsorbs to the zinc sulphate with no affinity to the which forms ionic bond. Hydrophobic region binds to air bubble which carries zinc sulphides to surface causing adsorbed to the surface. Common collector’s sulphides and xanthate ions. I.e. sodium ethyl xanthate. They are reagents selectively adsorb to surface of zinc sulphide ions of crushed ore. The froth removes which allows minerals to float to the surface as froth and minerals and the impurities sink to the bottom base and are then removed
Conversion – Zinc Sulphate (ZnSO4)
The zinc sulphide is converted to zinc sulphate in a two-step process. First there is the combustion that to form zinc sulphide to zinc oxide through roasting temperature of 1000- 1100 degrees forming the zinc oxide. It then forms to zinc sulphate through reacting with sulfuric acid to form zinc sulphate. Zinc powder is added which displaces ions of less reactive impurities. Cadmium can be used to purified and sold. Electrolysis in Zinc sulphide. Zinc ions molecules are then reduced to form zinc solid through reduction at the cathode. Water is oxidised to form oxygen water and electrons.
Describe the relevance of the metals reactivity for the production process.
Some metals are more reactive than other metals i.e. Potassium is the most reactive then gold is the least reactive. The method of reduction in the reduction stage is dependent on the reactivity of the metals and available energy. I.e. the gold is uncombined found as an element thus only removing impurities is required to obtain metal and combined molecules where their elements have been oxidised, hence reduction is not required.
Elaborate on combined metals.
Metals can exist as combined form with compounds such as oxygen and sulphur in the Earth’s crust. The oxidation number then increases as the electrons lost amount increases. Consequently, showing how much oxygen was lost. Molten for very reactive, electrolysis or reduction of a solid oxide through using reducing agent. Copper is roasted and uncombined metals don’t require reduction. Reducing agent depends on likely product.
Whats the deal with carbon dioxide use to reduce metals.
Carbon monoxide is used as an inexpensive method to reduce a metal. I.e. Iron is used to be reduced by carbon creating molten iron. With CO or CO2 as reaction. Carbon monoxide is also an effective reducing agent. Emissions, heat required non-renewable energy, may produce soot, large energy input for reaction.
Describe why reactive metals cannot be reduced in water.
The most reactive metals undergo reduction to maintain the metal. Zinc is obtained in aqueous solution. The water is then oxidised to form proton and oxygen. Moreover, above zinc is molten electrolysis. Typically, water reduction is favoured above the reactive metal thus anhydrous reaction is required. The reaction reduces the sodium and the chloride ion is oxidised. The reaction is expensive through electrolysis causing combustion of pollutants and greenhouse gas emissions. Thermal energy input required.
What is the deal with recycling
The recycling of materials includes breaking down waste material to more useful products. The recycling of materials is becoming more increasingly important as the metal ores are finite and the non-renewable recourses must be preserved for future generation. The recycling of lead and aluminium is roughly 50% from scrap.
What are the benefits of recycling material
The material preserves finite recourses. Metal is expensive to creates large amounts of material, damages environment. Metal reduces emissions of soot, carbon monoxide, nitrogen oxide, and nitrogen oxides in metal production. Lowers greenhouse emissions reduces energy used associated with petroleum. Recycling used from solvent mostly from non-renewable energy. Waste materials are produced in production and can harm environment. Reduces landfill as metal in landfill is not reused.
What are the two types of recycling polymers methods.
Two methods of recycling polymers involve feedstock recycling and mechanical recycling. Mechanical recycling involves the physical break down of molecules, through melting, granulation and shredding. Whereas, feedstock recycling involves the creation of monomers in polymerisation of fuels. Conserves the petroleum that is finite. Conserves the use of less energy synthesising material and in landfill reduction. Moreover, plastic polymers are 100% useable and reused until structural integrity fails. The reduction is harder to recycle, they do not melt after prolonged heating they are shredded into smaller pieces into filler materials.
Disadvantages of recycling
Disadvantages involves collection, separation and repurposing of material.
Provide information regarding how tungsten and titanium are reduced.
Titanium oxide is converted to titanium chloride before being used reduced to elements titanium, as it creates carbide. Titanium oxide is converted to titanium chloride before being reduced by magnesium. Tungsten is reduced by hydrogen gas. Fossil fuel, air must remove in air reaction vessel as hydrogen explodes.
Describe what composite materials are
Composite materials compromise two or more constituent materials to produce a material with properties different from individual components. It is prepared by combining 2 or more materials with different properties to create a unique material with properties that is not able be obtained by a single component. The matrix and reinforcement the matrix is the bulk of the material (matrix, or polymer), while the reinforcement is dispersed in the matrix material. (particles and fibres). Particles is distributed randomly, fibre is woven into or disturbed randomly into matrix.
Fibreglass as an example of composite material
Fibreglass glass fibre enforced plastic is a composite material which involves the glass fibres distributed in a thermoset matrix. Glass is brittle and cannot be easily worked to complex shapes. The glass fibre is stronger than glass, can be moulded before thermoset and is not brittle.
Advantage of composite material
The materials are stronger and can be used to improved that is not in present in individual components. They can be designed for a particular use as matrix and reinforcement. Most composite can be moulded into complex shapes.
Describe the recycling of composites.
The reclycing is difficult as cross links, and cannot be reshaped. Involves grinding material to small pieces which can be used as filler or melt the or combust matrix and retain fibres. Prylosis is used to recover expensive carbon fibres. Carbon fibres retain more than 90% of original mechanical matrix.
