C5- Metal extraction using carbon and electrolysis
Metals are extracted from ores. An ore is a rock that contains enough of a mineral (metal compound) for the metal to be extracted from it. Most metals are extracted from an ore by reduction with carbon or by electrolysis. Electrolysis is is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them.
For electrolysis to work, the ions must be free to move. Ions are free to move when an ionic substance is dissolved in water or when melted. For example, if electricity is passed through molten lead bromide, the lead bromide is broken down to form lead and bromine.
Metals such as zine, iron and copper are present in their ores as their oxides (a compound in which oxygen is bonded to one or more electropositive atoms) Each of these oxides is heated with carbon to secure the metal. The metal oxite loses oxygen and is therefore reduced. The carbon gains oxygen and is therefore oxidised.
Iron oxde+carben->iron +carbon dioxide
Some metals, such as aluminium are so reactive that they cannot be reduced by carbon
Ionic compounds contain charged particals called ions. For example, copper (II) chlride contains positively charged copper ions and negatively charged chloride ions. Ionic substances can be broken negatively down into the elements they are made from by electricity, in a process called elctrolysis. For electrolysis to work, the irons must be free to move. When an ionic compound is dissolved in water, or melts, the ions break free from the ionic lattice. These ions are then free to move. An example is, if electricity is passed through copper(II) chloride solution, then the copper (II) chloride is broken down to form copper metal and chlorine gas. There is a similar result if electricity is passed through molten copper (II) chloride)
This is what happens during electrolysis:
-Positively charged ions move to the negative electrode-(a conductor through which electricity enters or leaves an object, substance, or region.)
-Metal ions are positively charged, so metals are produced at the negative electrode.
-Negatively charged ions move to the positive electrode. Non-metal ions such as oxide ions and chloride ions, are negatively charged, so gases such as oxygen or chlorine are produced at the positive electrode.
C5- Relative atomic mas
In all chemical reaction there is always a product. The greater the amount of reactants used, the greater the amount of products produced. The total mass of the reactants used is equal to the total mass of the products made.
The relative atomic mass is a measure of the mass of one atom of the element.