Q1 The Earth's crust contains metals and metal compounds. These are always found mixed with other substances. In airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop, the metal or metal compound is airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop enough to make it economic to extract the metal. An unreactive metal like airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop, is found in the Earth as the metal itself and so airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop separation is not always needed. The reactivity series of metals lists metals in order of their reactivity, the most reactive metal being placed at the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop of the list and the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reactive at the bottom.

Q2 A more airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop metal can displace a airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reactive metal from its compounds. The non-metal elements airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop and hydrogen will also displace less reactive metals from their airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. You can use the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop of a metal in the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop series to predict how the metal can be extracted from a compound.

Q3 Often an ore contains a metal airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop or a substance which can easily be changed into a metal oxide. To extract the metal, the oxygen must be airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop from the metal oxide. This is called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. How a metal is extracted from its ore depends on how airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop the metal is. A metal such as iron, which is airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reactive than carbon, can therefore be extracted from its ore using carbon. Metals which are airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reactive than carbon, like airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop are extracted by airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. 

Q4 The solid raw materials used in the blast furnace are an iron ore called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop, the fuel and reducing agent airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop and limestone. The 4th raw material is hot airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop (oxygen supply) is blown into the furnace and this causes the coke to burn forming airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop and releasing energy (an airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reacion). At the high temperatures in the furnace the carbon dioxide reacts with coke to form airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. The carbon monoxide airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop the iron oxide in the iron ore (by removing the oxygen) to form molten iron which flows to the bottom of the furnace. The carbon monoxide combines with the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop from the iron ore to produce carbon dioxide. This is called oxidation. The airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop is added to remove acidic impurities like silica (silicon dioxide), forming a molten airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop that floats on the surface of the molten airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop.

Q5 Reactive metals such as aluminium are extracted by electrolysis. When substances which are made of airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop are dissolved in water, or airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop, they can be broken down (airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop) into simpler substances by passing an airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop current through them. This process is called electrolysis. When an ionic substance is melted or dissolved in water the ions are airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop to move about. During electrolysis, airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop charged ions for example, metal ions move to the negative electrode, and airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop charged ions move to the positive electrode. During electrolysis, gases may be given off, or metals deposited at the electrodes.

Q6 The raw material for producing aluminium is airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop, purified from an aluminium ore called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. Because aluminium oxide has a very airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop melting point it is dissolved in a molten aluminium compound called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop to lower the melting point. Both electrodes are made of airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. The aluminium forms at the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop electrode and oxygen forms at the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop electrode. This makes the positive electrodes airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop away quickly so that they frequently have to be airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop as they are airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop to carbon dioxide.

Q7 Copper can be purified by electrolysis using a positive electrode made of the airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop copper and a negative electrode made of of airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop copper. Both are dipped into a solution of copper airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop containing copper airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop (Cu²⁺).

Q8 At the negative electrode, positively charged ions gain electrons, a process called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. At the positive electrode negatively charged ions lose electrons in a process called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop. In a chemical reaction oxidation always occurs with airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop . These are called airaluminiumbauxiteburncarbonchemicalcokeconcentratedcryolitedecomposeddioxideelectricelectrolysisexothermicfreegoldhaematitehighimpureionsironleastlesslimestonemeltedmonoxidemorenegativenegativelyoresoxidationoxideoxidesoxidisedoxygenpositionpositivepositivelypurereactivereactivityredoxreducesreductionremovedreplacedslagsulphatetop reactions.