Topic 2 Chemical Properties of Metals

Topic 2chemical properties of metals 

The use of metals is not only closely related to their physical properties, but also closely related to their chemical properties.

For example, the production of aluminum has been greatly increased in just over a hundred years, and it has been widely used. In addition to improving the smelting method of aluminum, its cost is greatly reduced, and the density of aluminum is relatively small. Also due to the good corrosion resistance of aluminum. So why does aluminum have such good corrosion resistance?

 1.the reaction of metal and oxygen

 From previous studies, we already know that both magnesium and iron can react with oxygen. Experiments have shown that most metals can react with oxygen, but the ease and intensity of the reaction are different . For example, magnesium, aluminum, etc. can react with oxygen at normal temperature. Aluminum reacts with oxygen in the air, and a dense aluminum oxide ( Al2O3) film is formed on its surface to prevent further oxidation of aluminum. Therefore, aluminum has good corrosion resistance.

 Iron, copper, etc. hardly react with oxygen at normal temperature, but they can react with oxygen at high temperature. "True gold is not afraid of fire " means that gold does not react with oxygen even at high temperatures. It can be seen from the above experimental facts that magnesium and aluminum are more active, followed by iron and copper, and gold is the least active.

 2. The reaction of metals with hydrochloric acid and dilute sulfuric acid

 Many metals can react not only with oxygen, but also with hydrochloric acid or dilute sulfuric acid. Whether the metal can react with hydrochloric acid or dilute sulfuric acid can reflect the mobility of the metal.

 All these reactions are caused by the reaction of one element and one compound to form another element and another compound. This reaction in which a simple substance reacts with a compound to form another simple substance and another compound is called a displacement reaction.

 From the above research, it can be concluded that the metal mobility of magnesium, zinc, and iron is stronger than that of copper, and they can replace hydrogen in hydrochloric acid or dilute sulfuric acid.

 3. The order of activity of metals

 We already know that when an iron nail is placed in a solution of copper sulfate, purple-red copper will form on the iron nail. This shows that the metal mobility of iron is stronger than that of copper, and it can replace copper from the copper sulfate solution, which is one of the basis for comparing metal mobility.After many explorations similar to the above-mentioned experiments, people have carried out a serious analysis from the outside to the inside, and concluded and summarized the order of activity of common metals in solution: K Ca Na Mg Al Zn Fe Sn Pb (H) Cu Hg Ag Pt Au

 The activity sequence of metals has important applications in industrial and agricultural production and scientific research, and it can give you the following basis for judgment:

 1.In the order of metal activity, the higher the position of the metal, the stronger its activity;

 2.In the order of metal activity, the metal in front of hydrogen can replace hydrogen in hydrochloric acid and dilute sulfuric acid;

 3.In the order of metal reactivity, the metals at the front can displace the metals at the back from the solution of their compounds.

 You should know after finishing this topic

 1.Many metals can react with oxygen, hydrochloric acid, dilute sulfuric acid, etc., but the difficulty and intensity of the reaction are different.

 2.The reaction in which a simple substance reacts with a compound to form another simple substance and another compound is called a displacement reaction. The reactions between metals and hydrochloric acid, dilute sulfuric acid, and iron and copper sulfate solutions are all displacement reactions.

 3, The activity sequence of metals can be used as a basis for judging whether metals can undergo substitution reactions in solution.