Chemistry Topic 4 - Chemical Changes

State whether the following pH values are acidic, alkaline or neutral. a) 9, b) 2, c) 7, d) 6
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What is the general word equation for the reaction of a metal with an acid?acid + metal -> salt + hydrogenGive the balanced equation for the reaction of calcium with water.Ca + 2h20 -> Ca(OH)2 + H2Will copper react with water?NoWhat product forms in the oxidation of magnesium by oxygen?Magnesium oxideExplain how you decide whether a metal can be extracted from its oxide by reduction with carbon.If a metal is less reactive than carbon, it can be extracted from its oxide by heating with carbon.Why is gold found as itself in the earth?Gold is highly unreactiveIn terms of electrons, give the definition of oxidation.Loss. (OIL RIG - Oxidation Is Loss, Reduction Is Gain)In a displacement reaction, does the metal atom get reduced or oxidised?In displacement reactions, it's always the metal ion that gains electrons and is reduced. The metal atom always loses electrons and is oxidised.During electrolysis, which electrode are the positive ions attracted to?Negative electrodeWhy can ionic solids not undergo electrolysis?Ionic compounds in the solid state cannot conduct electricity since they have no free ions that can move and carry the charge. The ions must be able to move and can only do so in the molten state or when dissolved in a solution, usually aqueous.Do ions get reduced or oxidised at the anode?oxidisedDuring the manufacture of aluminium from bauxite, which electrode is aluminium formed at?The pure aluminum is attracted to the cathode, which is a lining of graphite.In what situation will hydrogen gas be given out during the electrolysis of an aqueous solution of an ionic solid?Hydrogen will be produced if the metal is more reactive than hydrogen.If halide ions are present in an aqueous solution of an ionic solid will oxygen gas be released?Oxygen is produced (from hydroxide ions), unless halide ions (chloride, bromide or iodide ions) are present. In that case, the negatively charged halide ions lose electrons and form the corresponding halogen (chlorine, bromine or iodine).What test could you use to determine if hydrogen gas has been produced in an electrolysis reaction?Squeaky pop - lighted splint goes out with a squeaky pop noise