When the mixture of solid and liquid is separated by filtration, the insoluble solid in the liquid is removed. (Funnel, filter paper, glass rod, beaker)
Evaporation is constantly stirred. When there are many crystals, turn off the lights and evaporate the residual heat to prevent overheating and splashing. Concentrate the dilute solution or dry the solution containing solid solute and evaporate it in an evaporating dish.
Distillation ① Liquid volume ② Heating mode ③ Mercury ball position of thermometer ④ Cooling water flows to prevent liquid from boiling; Use different boiling points to remove impurities (distillation bottles, alcohol lamps, thermometers, condensation tubes, liquid receiving tubes, conical bottles) that are difficult to volatilize or nonvolatile in liquid mixtures.
Extraction extractant: the solvents in the stock solution are immiscible with each other; ② The solubility of solute is much greater than that of original solvent; ③ It should be volatile. Using the solubility difference of solute in immiscible solvents, the operation of extracting solute from the solution composed of it and another solvent with one solvent, the main instrument: separation funnel.
The operation of separating the lower liquid from the lower end and pouring the upper liquid from the upper end to separate two liquids that are immiscible with each other is used together with extraction.
The operation of cleaning the sediment on the filter is to inject distilled water into the funnel so that there is no sediment on the water surface, and repeat the operation several times after the water flow is over.
Instrument tray balance (or measuring cylinder), beaker, glass rod, volumetric flask and rubber-tipped dropper needed to prepare a solution with a certain substance concentration.
Main steps: (1) calculation; (2) Weighing (if it is liquid, measure with burette); (3) Dissolve (a small amount of water, stir and pay attention to cooling); (4) Transfer the liquid (leak-check the volumetric flask first, and empty the glass rod); (5) Washing (the washing liquid should be transferred to the volumetric flask together); (6) shake it; (7) Fixed volume; (8) Shake well.
The temperature and range are marked on the volumetric flask. ② There are only scribed lines on the volumetric flask, and there is no scale. (1) Only the specified volume of solution can be prepared in the volumetric flask; ② Do not use a volumetric flask to dissolve, dilute or store the solution for a long time; ③ The volumetric flask cannot be heated, and the temperature of the solution transferred into the flask is about 20℃.
The first chapter is about the application of chemical 2- chemometrics in experiments.
The amount of 1 substance actually represents a group containing a certain number of particles.
A unit of molar matter.
3 standard conditions STP 0℃ and 1 standard atmospheric pressure
4 Avon Garderot constant NA 1mol The number of particles contained in any substance is 6.02× 1023.
5 mol mass M 1mol The mass of any substance is numerically equal to the relative mass.
6 molar volume of gas Vm 1mol The volume of any gas under standard conditions is about 22.4l L l.
7 Avon Gadereau's Law (derived from PV=nRT) Any gas with the same volume at the same temperature and pressure has the same number of molecules.
n 1 N 1 V 1
n2 N2 V2
8 concentration of substance CB 1 L The concentration expressed by the amount of substance of solute B in the solution.
CB=nB/V nB=CB×V V=nB/CB
9 the mass of the substance m m = m× n n = m/m m = m/n.
10 standard gas volume v v = n× vmn = v/vmvm = v/n.
1 1 number of particles of a substance n n = na× n n = n/na na = n/n.
12 number concentration CB of substance and mass fraction ω of solute1000× ρ× ω.
M
Dilution law of 13 solution c (concentration) ×V (concentration) =C (dilution )× v (dilution)
Centering on the quantity of matter
Chapter II Chemical Substances and Their Changes-1- Substance Classification
1 Element classification: metallic and nonmetallic elements
2 Classification of compounds: organic (containing C) and inorganic.
Oxides Acid oxides (react with alkali to form salt and water) Silicon dioxide, sulfur dioxide, carbon dioxide, SO3, nitrous oxide (mainly nonmetallic oxides).
Basic oxides (which react with acids to form salts and water) Fe2O3, CuO, MgO (mainly metal oxides),
Amphoteric oxides (which react with acids and bases to form salts and water) Al2O3 and ZnO.
Non-salt oxides NO2, NO, CO (the valence of N in salt is not +2, +3, and C is not +2).
Dispersion system solution (very stable) dispersoid particles are less than 65438±0nm, transparent, stable and uniform.
Colloidal (metastable) dispersoid particles 1nm- 100nm are relatively transparent, stable and uniform.
The dispersoid particles of turbid liquid (suspension and emulsion) are larger than 100nm, opaque, unstable and uneven.
Classification of chemical reactions There are four basic reaction types: 2SO2+ O2 2SO3.
Decomposition: 2NaHCO3 Na2CO3 +CO2↑+ H2O
Replace: Cl2+2ki = = 2kcl+I2
Double decomposition: 2nh4cl+Ca (OH) 2calcl2+2nh3 ↑+2h2o.
Whether ions participate in the reaction (electrolyte in aqueous solution) Ion reaction: Cl2+H2O = HCl+HCLO.
Non-ionic reaction: 2Fe+3cl2 2fecl3
Whether there is an element electron gain or loss or deviation (up or down) redox reaction: 2na+2h2o = 2nNaOH+H2 ↑.
Non-redox reaction: Al(OH)3+NaOH = NaAlO2+2H2O.
Exothermic or endothermic reaction: 3Fe+2O2 Fe3O4
Endothermic reaction: C+CO2 2CO
Chapter II Chemical Substances and Their Changes -2- Ion Reaction
Electrolytes (acid, alkali, salt, water) can conduct electricity in aqueous solution or molten state.
Non-electrolyte compounds (including carbon dioxide and sulfur dioxide) cannot conduct electricity in aqueous solution or molten state.
Ionization equation of H2CO3H++HCO3- (weak electrolyte)
The ionization equation of NaHCO3 is nahco3 = Na++HCO3- (strong electrolyte is "=").
The ion reaction formula is expressed by the ions actually participating in the reaction.
Write the ion reaction formula, change it, delete it, check it, check it.
Simple materials, oxides, gases and insoluble and difficult-to-ionize substances should retain their molecular formulas.
Ion * * * contains colored ions MnO4- purplish red, Fe3+ brownish yellow, Fe2+ light green and Cu2+ blue.
With H+ * * * (weak acid radical) OH-, CO32-, SO32-, SiO32-, AlO2-, S2-, F-, etc.
With OH- not * * * (weak base metal cation) H+, Fe3+, Fe2+, Fe3+, Cu2+, Al3+, Mg2+, NH4+, etc.
HCO3-, HSO3-, HS- etc. Not stored with H+ and OH-.
Ba2+, Ca2+ and SO42-, CO32- Ag+ and Cl- usually form and precipitate.
Properties of colloid (metastable state) Tindal phenomenon, Brownian motion, electrophoresis, aggregation
The simplest way to judge colloid is Tyndall phenomenon.
Colloidal purification dialysis (colloidal particles cannot penetrate the semi-permeable membrane)
Preparation method of Fe(OH)3 colloid Take a beaker, put it into 20mL distilled water, heat it until it boils, and then add saturated FeCl3 solution 1 ml ~ 2 ml drop by drop. Continue to boil until the solution is reddish brown. The red-brown liquid Fe(OH)3 colloid was observed.
Preparation equation of Fe(OH)3 colloid FeCl3+3H2O Fe(OH)3 (colloid) +3HCl
Conditions of colloid coagulation: heating, adding electrolyte and adding colloid with opposite electrical properties.
Chapter II Chemical Substances and Their Changes -3- Redox Reaction
The essence of redox reaction is electron transfer (gain or loss or deviation)
The rise and fall of valence of characteristic elements in redox reaction (not necessarily the gain or loss of oxygen)
Hypoxia reductant, reducibility, electron loss, (valence increase), oxidation, oxidation reaction into oxidation products.
Reducing agent, oxidizing, gaining electrons, (reducing the price), being reduced, having a reduction reaction, forming a reduction product.
The combination reaction is not necessarily a redox reaction. Generally, the combination reaction with a single substance or the decomposition reaction with a single substance is a redox reaction.
decomposition reaction
The displacement reaction must be a redox reaction.
Displacement reaction cannot be redox reaction.
Use wet red litmus test paper to test that NH3 turns blue.
SO2 inspection supplies: the red solution fades.
KMnO4 solution (strong oxidizing) is used to absorb SO2.
Clarified limewater used for CO2 detection becomes turbid.
Using wet KI starch test paper, Cl2 turns blue.
Exposed to the air after opening the bottle cap, it turned red and brown without inspection.
After the examination of ion NH4+ is heated with NaOH solution, the released gas turns blue with wet red litmus paper.
The red-brown precipitate in NaOH solution of Fe3+ test is blood red in KSCN solution.
Examination of Fe ~ (2+) ① White precipitate immediately turns gray-green in NaOH solution, and finally turns red-brown; There is no phenomenon in KSCN solution, and blood red appears after adding chlorine water.
The test of SO _ 42-showed that there was no phenomenon when HCl was added first, and white precipitate insoluble in acid was found when BaCl2 _ 2 solution was added later.
After adding nitric acid solution, Cl-, (Br-, I-) white precipitated AgCl (light yellow precipitated AgBr, yellow precipitated AgI) appeared.
Inspection of NO3-After concentration, add a small amount of concentrated sulfuric acid and several pieces of copper to heat the reddish-brown gas to release NO2.
The substances K and Na are preserved in kerosene (waterproof and O2-proof).
Brown bottles (nitric acid, silver nitrate, chlorine water, perchloric acid, etc. For substances that are easily decomposed by light.
Glass plugs (Na2SiO3, NaOH, Na2CO3) cannot be used for rubber plugs of alkaline substances.
Rubber stoppers (HSO4, HNO3, KMnO4) cannot be used for glass stoppers of acidic and strongly oxidizing substances.
Material preservation F2, HF (hydrofluoric acid) plastic bottles can't use glass bottles (react with SiO2 to corrode glass).
White phosphorus is stored in water (to prevent spontaneous combustion in the air), Br2 (to prevent volatilization).
The most abundant elements in the earth's crust are oxygen, silicon, aluminum and iron.
There are free elements of gold, iron (meteorite) and sulfur (near the crater) in the crust.
The physical properties of metals are metallic luster, opacity, easy conductivity, thermal conductivity and ductility.
Amphoteric substances that can react with HCl and NaOH: Al, Al2O3, Al(OH)3.
Acid salts of weak acids: sodium bicarbonate, sodium bisulfite, sodium bisulfite.
Ammonium salts of weak acids: (NH4)2CO3, (NH4)2S.
Amphoteric metals zinc, aluminum and aluminum (H2 is released with acid and alkali)
Passivating metallic iron and aluminum (cooled concentrated H2SO4 and concentrated HNO3)
The chemical properties of acids are relatively thin, and the commonness of concentrated sulfuric acid is 1, which is strongly acidic-reacting to form salts.
2. High boiling point acid, not volatile-preparation of volatile acid
The characteristics of concentrated sulfuric acid 1, water absorption -NH3 and H2S can not be dried.
2. Dehydration-dehydration and carbonization of organic matter.
3. Strong oxidation-reaction with inert metals, nonmetals and reducing substances.
HNO3 1, strong acidity 2, strong oxidation 3, unstable (see light and heat)
Hclo hypochlorite 1, weak acidity 2, strong oxidation 3, instability (see light and heat)
Silicate H2SiO3 1, weakly acidic 2, insoluble 3, unstable (thermal)
Bleaching oxidation type (permanent) strong oxidation: HClO, Na2O2, O3, concentrated H2SO4, concentrated HNO3.
Additive (temporary) SO2 (makes magenta fade, but can't make litmus red and then fade)
Aluminum hydroxide colloid produced by alum solution adsorbing (physical) activated carbon.
The main components of chlorine water in aqueous solution are Cl2, H2O and HClO.
Ions: h+, cl-, ClO-
Main components of ammonia water
Molecules: ammonia H2O Ammonia H2O
Ion: NH4+ohˇ
The difference between chlorine water and liquid chlorine, ammonia water and liquid ammonia chlorine water, ammonia mixture, liquid chlorine and liquid ammonia are pure substances.
The difference between chlorine atom Cl and chloride ion Cl- The outermost layer has different electronic and chemical properties, and the structure of chloride ion Cl- is stable.
Gas is very soluble in water (fountain) NH3 (1:700) HCl (1:500).
NO2 NH3 HCl can only be collected by exhaust method.
I can't. N2 carbon monoxide can only be collected by exhaust method.
Reaction phenomena of sodium and water: ① floating, ② melting, ③ swimming, ④ hissing, ⑤ red ① sodium floats on the water surface-the density is less than that of water; (2) water vapor-exothermic; (3) melting into pellets-low melting point; (4) swimming on the gas that generates water; Make noise-violent reaction; ⑤ Discoloration-alkali production
Common name soda Na2CO3, baking soda NaHCO3, sodium silicate: Na2SiO3. The main components of aqueous bleaching powder are Ca(ClO)2 and CaCl2, and the effective component is Ca(ClO)2.
Objective Na2O2 _ 2 (light yellow) is used as a respiratory mask, and Al (OH) _ 3 and NaHCO3 _ 3 (baking soda) can neutralize gastric acid.
Alum is used as water purifying agent, and HClO hypochlorite is used for sterilization, disinfection, permanent bleaching and SO2 temporary bleaching.
Cl2 is commonly used for disinfection and sterilization of tap water, but it will produce carcinogenic organic chlorine, which is replaced by chlorine dioxide (ClO2).
Fe2O3-red paint and coating; Al2O3-refractory, NH3 can be used as nitrogen fertilizer and refrigerant.
Crystalline silicon Si is used as semiconductor and solar cell; Silicon dioxide can be used as optical fiber; Silica gel is a common carrier of desiccant and catalyst. Sodium silicate can be used as soap filler, wood preservative, fire retardant and adhesive.