量变引起质变（Quantitative change causes qualitative change）.doc

量变引起质变（Quantitative change causes qualitative change） Interactions of two substances, because on the one hand, the amount of the change and cause the qualitative change of the product, or as a result of drug to join a different order and lead to different results, or as the reaction progresses, the concentration of the acid changed, product is changed, the above examples are common in the middle school chemistry, frequently appear in the college entrance examination. In order to better grasp the characteristics of this kind of reaction, we will according to the double decomposition reaction of chemical reaction, REDOX reaction, complexation reaction, hydrolysis reaction, substitution reaction, addition reaction type 59 quantitative change causes qualitative classified into 11 types of chemical reaction, the points above are as follows: 1. REDOX - REDOX type 1. The reaction of sodium (small amount, excessive) with oxygen 2Na + O2 Na2O2 + 2Na = 2Na2O 2. The reaction of carbon (small amount, excessive) with oxygen C + O2 CO2 + C2CO 2C + O2 2CO Note: carbon monoxide is produced when oxygen is inadequate and can cause gas poisoning. 3. The reaction of carbon and oxygen (small amount, excessive) 2C + O2 2CO + O2 2CO2 C + O2 2CO2 4. The reaction of silicon dioxide and coke (small amount, excessive) SiO2 + 2C Si + 2CO arrow Si + C SiC SiO2 + 3C 2CO Note: when making the coarse silicon, control the amount of coke, otherwise the coarse silicon will not be obtained, and the silicon carbide will be obtained. 5. Reaction of red phosphorus and chlorine gas (small amount, excessive) 2 p + 3 Cl2 2 PCl3 PCl3 + Cl2 = PCl5 Note: the experiment saw the phenomenon: white smoke, the composition of smoke PCl5, the composition of fog is PCl3. Hydrogen sulphide reacts with oxygen (a small amount of excess) 2H2S + O2 2S + 2H2O + O2SO2 2H2S + 3O2 2 + 2H2O Note: H2S is toxic, and the combustion product SO2 is also toxic, which cannot be used to treat H2S exhaust. 7. Hydrogen sulfide (small amo