1. Generally, chlorine is yellow-green, toxic, irritating, denser than air, lower in melting point, soluble in water, soluble in organic solvents, and easy to liquefy at pressure10/kpa and temperature -34.6℃. If the temperature continues to cool to-10 1℃, liquid chlorine will become solid chlorine. 1 volume of water can dissolve 2 volumes of chlorine at room temperature.
The density is 3.214g/L. The melting point is-100.98℃ and the boiling point is -34.6℃. Valence-1,+1, +3, +5 and +7. The ionization energy is 12.967 eV, and it has strong oxidation ability, and can carry out substitution and addition reactions with organic and inorganic substances. It can react directly with many metals and nonmetals.
2 high school learning methods. Chlorine gas is toxic, and the way to smell the toxic gas is (fan method): fan the bottle mouth gently with your hands to make a very small amount of gas float into your nostrils.
Second, the chemical properties
1. Reacting with metals: Chlorine has strong oxidizing property, which can oxidize almost all metals.
2Na+Cl2=2NaCl (yellow flame, white smoke)
2Fe+3Cl22FeCl3 (red heat, forming brown smoke)
2Na+Cl2=2NaCl (phenomenon: intense combustion, white smoke)
Cu+Cl2=CuCl2 (phenomenon: intense combustion, brown smoke)
2Fe+3Cl2=2FeC2。
2. Reaction with nonmetals: simple materials such as silicon, phosphorus and sulfur can burn in chlorine, and phosphorus can burn in chlorine to form white smoke.
2P+ carbon trichloride phosphorus dichloride (liquid)
PCl3+Cl2=PCl5 (solid)
Combustion: A violent chemical reaction that emits light and heat.
React with water
In this reaction, the oxidant is Cl2, the reductant is Cl2, and the ion reaction equation is rewritten as Cl2+H2O.
H++Cl-+HClO
The aqueous solution of (1) chlorine gas is called chlorine water, and the saturated chlorine water is yellow-green with irritating smell. The main particles are Cl2, H2O, HClO, H+, Cl- and ClO-.
(2) the nature of hypochlorous acid
Weak acidity: it is a weak acid, belonging to weak electrolyte, and its acidity is weaker than carbonic acid.
Perchloric acid+sodium hydroxide = sodium hypochlorite +H2O
NaClO+HCl=HClO+NaCl
2NaClO+CO2+H2O=Na2CO3+2HClO
② Instability:
Due to the decomposition of HClO, Cl2 gradually reacts with water until chlorine water fails, so chlorine water should be prepared and stored in brown reagent bottle now. If left for a long time, chlorine water will become dilute hydrochloric acid.
③ Strong oxidizability: HClO can oxidize many substances.
Sterilization and bleachability: It can make colored cloth strips, magenta reagents and other colored substances fade, and its principle is mainly to use its strong oxidation.
Description: Dry Cl2 itself is not bleachable, but it is only bleachable when it is converted into HClO.
4. Reacting with hydrogen:
Pure hydrogen can be burned in chlorine. When hydrogen and chlorine are mixed into a light flame, it will explode if it is illuminated or ignited by strong light.
5. Reaction with alkali:
Cl2+2NaOH=NaCl+NaClO+H2O (unprocessed hypochlorite at room temperature)
3Cl2+6KOH5KCl+KClO3+3H2O (chlorate is produced when heated).
2cl2+2ca (oh) 2 = CaCl2+ca (clo) 2+2h2o (the obtained mixture is bleached flour).
6. Reaction with salt:
Cl2+2Kl=2KCl+I2 (oxidized anion)
Cl2+2FeCl2=2FeCl3 (oxidized cation)
7. Reactions with hydrocarbons:
Cl2+CH4CH3Cl+HCl (substituted)
C6H6+3Cl2C6H6Cl6 (addition)
Common test sites
About the physical and chemical properties of chlorine, and the high frequency test sites of chlorine chemical reaction.
Common misunderstanding reminder
Danger:
Non-combustible, but it will burn and explode when it meets combustible materials.
Invasion route: inhalation, eye and skin contact.
Health hazards: severe irritation to skin, eyes and mucosa; At high concentration, it has asphyxiating effect, causing laryngeal muscle spasm, mucosal swelling, nausea, vomiting, anxiety and acute respiratory diseases, cough, chest pain, dyspnea, bronchitis, pulmonary edema and pneumonia; Even died of laryngeal muscle spasm.
Classical examples and analysis of chemistry in senior high school (including answers)
Classical example of chemistry in senior high school: After 22.4L gaseous nitrogen oxide compound completely reacts with enough luminous copper powder, the gas volume becomes 1 1, which is higher than 1.2l (the volumes are all measured under the same conditions), so the chemical formula of the nitrogen oxide is?
Analysis of classical examples of chemistry in senior high school;
Nitrogen oxides react with enough copper powder to produce nitrogen.
NXOY: N2 = 22.4:11.2 = 2:1,so there are:
2NxOy+2yCu==2yCuO+N2
According to the conservation of nitrogen atoms, 2x=2.
Then x= 1,
Y has countless solutions in this equation,
But combined with chemical knowledge,
Can only be y= 1 or y=2.
So NO or NO2
Equation:
2NO+2Cu = N2+2Cu
2NO2+4Cu=N2+4CuO