I. Safety in Chemistry Experiments

1. (1) When conducting experiments with toxic gases, they should be carried out in ventilated kitchens and attention should be paid to the proper treatment of the exhaust (absorption or ignition, etc.). When conducting experiments on flammable and explosive gases, attention should be paid to the purity test, and the exhaust gas should be burned off or treated appropriately.

(2) It is advisable to seek medical attention for burns.

(3) Concentrated acid spilled on the lab bench should be neutralized with Na2CO3 (or NaHCO3) and then washed away with water. If the acid gets on your skin, wipe it off with a dry cloth and then rinse it off with water. If you get acid in your eyes, rinse them with dilute NaHCO3 solution, then call a doctor.

(4) Concentrated alkali spilled on the experimental bench, first neutralized with dilute acetic acid, and then rinsed with water. If the alkali is stained on the skin, rinse with plenty of water and then apply boric acid solution. If you splash alkali in your eyes, wash them with water and then use boric acid solution to rinse them.

(5) Sodium, phosphorus and other misfires should be covered with sand.

(6) alcohol and other flammable organic small fire, should be quickly covered with a wet rag.

II. Separation and purification of mixtures

Separation and purification methods Separation of substances Matters to be noted Application examples

Filtration for solid-liquid mixture of separation of a paste, two low, three rely on the purification of such as crude salt

Distillation Purification or separation of liquid mixtures with different boiling points Prevent the liquid from boiling violently, the location of the thermometer's mercury bulb, such as the condensate tube of petroleum in the distillation of the flow of water such as the oil distillation of petroleum

Extraction of solutes in immiscible solvents with different solubility, with a solvent to extract the solute from the solution it consists of with another solvent The selection of the extractant should meet the following requirements: and the solvent is immiscible with each other in the original solution; solubility of solutes should be much greater than the original solvent extract bromine, iodine in bromine water with carbon tetrachloride

Separation of the separation of the liquid that is not mutually soluble. Separation of mutually insoluble liquids Open the upper end of the piston or make the groove on the piston and the water hole on the funnel, so that the air inside and outside the funnel is connected. Open the piston, so that the lower liquid slowly flow out, close the piston in time, the upper liquid from the upper end of the pouring such as carbon tetrachloride to extract bromine, iodine in the bromine water and then liquid separation

Evaporation and crystallization used to separate and purify the mixture of several soluble solids Heating evaporation dish to make the solution evaporate, the solution should be constantly stirred with a glass rod; when more solids in the dish, that is, stop the heating Separation of NaCl and KNO3 mixture

Separation of the liquid from a mixture of insoluble liquids

Separate the liquid from a mixture of insoluble liquids

Three, ion test

Ion added reagent phenomenon Ionic equation

Cl- AgNO3, dilute HNO3 produce white precipitate Cl- + Ag + = AgCl↓

SO42- dilute HCl, BaCl2 white precipitate SO42-+Ba2+=BaSO4↓

IV. Removal of impurities

Note: In order to make the impurities in addition to the exhaustion, the addition of reagents can not be the "right amount", but should be "too much"; but too much of the reagent must be easy to remove in the subsequent operation.

V. Units of quantity of matter - moles

1. The amount of matter (n) is a physical quantity that represents the collective containing a certain number of particles.

2. Mole (mol): any collective of particles containing 6.02 × 1023 particles measured as 1 mole.

3. Avogadro's constant: Call 6.02 X 1023mol-1 Avogadro's constant.

4. Amount of substance = number of particles contained in a substance / Avogadro's constant n = N/NA

5. Molar mass (M) (1) Definition: The mass of a substance per unit amount of substance is called molar mass. (2) Unit: g/mol or g..mol-1(3) Value: equal to the relative atomic mass or relative molecular mass of the particle.

6. Amount of substance = mass of substance / molar mass ( n = m/M )

VI. Molar volume of gases

1. Molar volume of gases (Vm) (1) Definition: The volume occupied by a gas per unit amount of substance is called the molar volume of the gas. (2) Unit: L/mol

2. Amount of substance = volume of gas / molar volume of gas n = V/Vm

3. Under standard conditions, Vm = 22.4 L/mol

VII. Application of amount of substance in chemical experiments

1. Concentration of amount of substance.

(1) Definition: the physical quantity that expresses the composition of a solution in terms of the amount of substance of solute B contained in a unit volume of the solution is called the concentration of substance of solute B. (2) unit: mol / L (3) the concentration of the amount of substance = the amount of solute / the volume of the solution CB = nB / V

2. The preparation of a certain amount of concentration of substances

(1) the basic principle: according to the volume of the solution to be prepared and the concentration of the amount of substance of the solute, the concentration of the material with the amount of material to be used in the calculation of the method of calculating the mass or volume of the solute required in the container to dilute the solute with a solvent to the specified amount of solvent. The solute is diluted in a container with a solvent to a specified volume, and the solution is prepared.

(2) the main operation

a. check whether the leakage. b. Preparation of solutions 1 calculation. 2 weighing. 3 dissolve. 4 transfer. 5 washing. 6 fixed volume. 7 shaking. 8 storage solution.

Precautions: A choose the same volume of the volumetric flask with the solution to be prepared. B must check for leaks before use. C can not be dissolved directly in the volumetric flask. D Dissolved solution cooled to room temperature before transferring. E when the volume is determined, when the liquid surface from the scale line 1-50px when switching to a burette, with a plain view of the method of observation and add water to the liquid surface of the lowest tangent to the scale until.

3. Solution dilution: C (concentrated solution) ?V (concentrated solution) = C (dilute solution) ?V (dilute solution)

I. Classification of substances

The system obtained by dispersing a substance (or substances) in another substance (or substances) is called the dispersion system. The material being dispersed is called a dispersant (can be gas, liquid, solid), the role of the material to accommodate the dispersant is called a dispersant (can be gas, liquid, solid). Solution, colloid, turbid liquid three kinds of dispersion system comparison

dispersible particle size / nm appearance characteristics can pass through the filter paper whether the Tyndall effect Examples

solution less than 1 homogeneous, transparent, stable, can not NaCl, sucrose solution

colloid between 1-100 homogeneous, some transparent, more stable, can be Fe (OH) 3 colloid

turbid liquid greater than 100 uneven, opaque, unstable can not have mud and water

Two, chemical changes in substances

1, a variety of chemical changes can occur between substances, based on certain criteria can be classified as chemical changes.

(1) According to the categories of reactants and products and the number of types of substances before and after the reaction can be divided into:

A, chemical reaction (A + B = AB) B, decomposition reaction (AB = A + B)

C, replacement reaction (A + BC = AC + B)

D, compound decomposition reaction (AB + CD = AD + CB)

(2) According to whether the reaction is attended by ions or not can be divided into:

A, ionic reactions: a class of reactions attended by ions. Mainly includes complex decomposition reactions and redox reactions with the participation of ions.

B, molecular reactions (non-ionic reactions)

(3) according to whether there is a transfer of electrons in the reaction can be divided into:

A, redox reactions: reactions in which there is a transfer of electrons (loss or shift)

Substantive: there is a transfer of electrons (loss or shift)

Characteristics: there is a change in the elemental valence of the elements before and after the reaction

There is a change in the elemental valence before and after the reaction

B, non-ionic reactions. p>

B, non-redox reactions

2, ionic reactions

(1), electrolytes: compounds that conduct electricity in an aqueous solution or in a molten state, called electrolytes. Acids, bases, salts are electrolytes. In aqueous solution or melted state can not conduct electricity compounds, called non-electrolytes.

Note: ① electrolytes, non-electrolytes are compounds, the difference is in aqueous solution or melted state can conduct electricity. ② electrolyte conductivity is conditional: electrolytes must be in aqueous solution or melted state to conduct electricity. ③ can conduct electricity is not all substances are electrolytes: such as copper, aluminum, graphite, etc.. (iv) Non-metallic oxides (SO2, SO3, CO2) and most organic matter are non-electrolytes.

(2), the ionic equation: with the actual ions participating in the reaction symbols to express the reaction formula. It represents not only a specific chemical reaction, but also the same type of ionic reaction.

Compound decomposition reaction This type of ionic reaction occurs when a precipitate, gas or water is produced. Writing method:

write: write the chemical equation of the reaction

demolition: soluble in water, easily ionized substances are written into ionic form

deletion: the ions that do not participate in the reaction from the ends of the equation

check: check the number of atoms at both ends of the equation and whether the number of charges are equal

(3), the ionic ****existence of problems

The so-called ions can be stored in a large number of **** in the same solution means that the ions do not react with each other in any way; if the ions can react with each other, they can not be stored in a large number of ****.

A, combined to generate insoluble substances of ions can not be a large number of **** survival: such as Ba2 + and SO42-, Ag + and Cl-, Ca2 + and CO32-, Mg2 + and OH-, etc.

B, combined to generate gases or volatile substances of the ions can not be a large number of **** survival: such as H + and C O 32-, HCO3-, SO32-, OH- and NH4 +, etc.

B, combined to generate gases or volatile substances of ions can not be a large number of **** survival: such as H + and C O 32-,HCO3-, SO32-, OH- and NH4+. NH4+, etc.

C. Ions that combine to form substances that are difficult to ionize (water) cannot exist in large quantities***: e.g., H+ and OH-, CH3COO-, OH-, and HCO3-.

D, redox reactions, hydrolysis reactions of ions can not be a large number of **** survival (to be learned)

Note: the conditions of the question: such as colorless solution should be excluded from the colored ions: Fe2 +, Fe3 +, Cu2 +, MnO4- and other ions, acidic (or alkaline) should be considered in addition to the given group of ions, and there is a large number of H + (or OH-). (4) ionic equation correct or incorrect judgment (six to see)

One, see whether the reaction is consistent with the facts: mainly to see whether the reaction can be carried out or whether the reaction products are correct

Second, to see whether you can write an ionic equation: reactions between pure solids can not be written in ionic equations

Third, look at the chemical terminology is correct: chemical formulas, ionic symbols, precipitates, gas symbols, and other symbols of the writing is consistent with the facts

four, to see whether the ionic ratio is correct

five, to see whether the number of atoms, the number of charges are conserved

four, to see whether the amount of the reaction related to the expression is correct (excess, the right amount)

3, redox reactions in the concepts and their interrelationships are as follows:

loss of electrons - valence increases - is oxidized ( oxidation reaction) - is a reducing agent (has reducing properties)

Gaining electrons - the valence decreases - is reduced (reduction reaction) - is an oxidizing agent (has oxidizing properties)

Metals and their compounds

I.

Metallic activity Na>Mg>Al>Fe.

II. Metals are generally more reactive and can easily react with O2 reaction to produce oxides, can react with acid solution to produce H2, especially active such as Na can react with H2O to replace H2, special metals such as Al can react with alkali solution to get H2.

Three,

A12O3 for amphoteric oxides, Al (OH) 3 for amphoteric hydroxides, can react with strong acids to produce salt and water, also can react with strong bases to produce salt and water. can react with strong bases to form salt and water.

IV.

V. Comparison of Na2CO3 and NaHCO3

Sodium carbonate Sodium bicarbonate

Common name soda ash or baking soda baking soda

Color white crystals white crystals fine white crystals

Water solubility Soluble in water, alkaline solution to make phenolphthalein red Soluble in water (but solubility is less than Na2CO3) solution is alkaline (phenolphthalein light red). Alkaline (phenolphthalein turns light red)

Thermal stability More stable, difficult to decompose when heated Easy to decompose when heated

2NaHCO3 Na2CO3 + CO2↑ + H2O

Reacts with acid CO32- + H + H CO3-

H CO3- + H + CO2↑ + H2O

H CO3- + H + CO2↑ + H2O

H CO3- + H + CO2↑ + H2O

The rate of CO2 release under the same conditions NaHCO3 is faster than Na2CO3

Reaction with alkali Na2CO3 + Ca(OH)2 CaCO3↓ + 2NaOH

Reaction essence: the decomposition reaction of CO32- and metal cations NaHCO3 + NaOH Na2CO3 + H2O

Reaction essence: the decomposition reaction of CO32- and metal cations NaHCO3 + NaOH Na2CO3 + H2O

Reaction substance: H CO3- + OH- H2O + CO32-

Reaction with H2O and CO2 Na2CO3 + CO2 + H2O 2NaHCO3

CO32- + H2O + CO2 H CO3-

No reaction

Reaction with salt CaCl2 + Na2CO3 CaCO3↓ + 2NaCl

Ca2+ + CO32- CaCO3↓

No reaction

Main uses Glass, paper, soap making, washing Fermentation, medicine, fire extinguishers

Transformational relationships

VI. Alloy: two or more metals (or metals and non-metals) fused together to form a substance with metallic properties.

Characteristics of alloys; generally harder than the constituent metals with lower melting points than the constituent metals, more versatile than pure metals.

Nonmetals and their compounds

A, silicon element: inorganic nonmetallic materials in the protagonist, in the earth's crust in the content of 26.3%, second to oxygen. Is a kind of pro-oxygen element

Element, with a high melting point of the oxide and silicate form exists in the rock, sand and soil, accounting for more than 90% of the mass of the earth's crust. It is located in Cycle 3, below Group IVA carbon.

Si vs. C

Has four electrons in its outermost layer and forms mainly tetravalent compounds.

II. Silicon Dioxide (SiO2)

Naturally occurring silicon dioxide is known as silica and includes both crystalline and amorphous forms. Quartz is a common crystalline form of silicon dioxide, of which colorless and transparent is crystal, with colored ring band or layer is agate. Silicon dioxide crystals have a three-dimensional reticulated structure, and the basic unit is [SiO4], so they are widely used for their favorable physical and chemical properties. (Agate ornaments, quartz crucibles, optical fibers)

Physical: high melting point, hardness, insoluble in water, clean SiO2 colorless translucent good

Chemical: good chemical stability, in addition to HF generally do not react with other acids, can be reacted with a strong alkali (NaOH), is an acidic oxides, can react with alkaline oxides under certain conditions

SiO2 + 4HF == SiF4 ↑ + 2H2O

SiO2 + CaO == (high temperature) CaSiO3

SiO2 + 2NaOH == Na2SiO3 + H2O

Can't use glass bottles to contain HF, reagent bottles for alkaline solutions should be corked or glued.

Three, silicic acid (H2SiO3)

Acid is very weak (weaker than carbonic acid) solubility is very small, due to the insolubility of SiO2 in water, silicic acid should be made by reacting with soluble silicates and other acids stronger than silicic acid.

Na2SiO3 + 2HCl == H2SiO3↓ + 2NaCl

Silica gel is porous and loose, and can be used as a desiccant, catalyst carrier.

Four, silicates

Silicates are composed of silicon, oxygen, metal elements of the compounds of the general term, widely distributed, complex structure and chemical stability. Generally insoluble in water. (Na2SiO3, K2SiO3 except) the most typical representative of sodium silicate Na2SiO3: soluble, and its aqueous solution called water glass and effervescent alkali, can be used as soap filler, wood fire retardant and adhesive. Commonly used silicate products: glass, ceramics, cement

four, silicon monomers

similar to carbon, crystalline and amorphous two. Crystalline silicon structure similar to diamond, gray-black solid with a metallic luster, high melting point (1410 ℃), hardness, brittle, chemically inactive at room temperature. Is a good semiconductor, applications: semiconductor transistors and chips, photovoltaic cells,

5, the element chlorine: located in the third cycle of Group VII A, atomic structure: easy to get an electron to form

Chlorine ion Cl-, a typical non-metallic elements, in nature to the existence of the chemical state.

Six, chlorine gas

Physical properties: yellow-green gas, irritating odor, soluble in water, pressurization and cooling conditions can be changed to liquid (liquid chlorine) and solid.

Method:MnO2＋4HCl (concentrated) MnCl2＋2H2O＋Cl2

Smell:Fan the bottle gently with your hand, so that a small amount of chlorine gas into the nostrils.

Chemical properties: very active, toxic, oxidizing, can be combined with most metals to form metal chlorides (salts). Can also react with non-metals:

2Na + Cl2 === (ignition) 2NaCl 2Fe + 3Cl2 === (ignition) 2FeCl3 Cu + Cl2 === (ignition) CuCl2

Cl2 + H2 === (ignition) 2HCl Phenomenon: Pale white flames, generating a large amount of white mist.

Combustion does not necessarily involve oxygen; substances do not burn only in oxygen. The nature of combustion is a violent redox reaction, and all violent chemical reactions that emit light and heat are called combustion.

Cl2 uses:

①Tap water sterilization and disinfection Cl2 + H2O == HCl + HClO 2HClO === (light) 2HCl + O2 ↑

1 volume of water to dissolve 2 volumes of chlorine gas to form a solution for chlorine water, light yellow-green. Among them, hypochlorous acid HClO has strong oxidizing and bleaching properties, playing a major role in disinfection and bleaching. Hypochlorous acid is weakly acidic, unstable, light or heat decomposition, so the chlorine water will be ineffective for a long time.

② system bleach, bleach and bleach

Bleach Cl2 + 2NaOH = NaCl + NaClO + H2O, the active ingredient NaClO more stable than HClO, can be stored for a long time to make bleach (35% of the effective chlorine) and bleach (full reaction of 70% of the effective chlorine) 2Cl2 + 2Ca (OH) 2 = CaCl2 + Ca (ClO)2＋2H2O

③Reacts with organic matter and is an important chemical industry substance.

④Used to purify Si, Ge, Ti and other semiconductors and titanium

⑤Organic chemical industry: synthetic plastics, rubber, synthetic fibers, pesticides, dyes and pharmaceuticals

seven, the test of chloride ions

Using silver nitrate solution and dilute nitric acid to exclude interfering ions (CO32-, SO32 -)

HCl + AgNO3 == AgCl ↓ + HNO3

NaCl + AgNO3 == AgCl ↓ + NaNO3

Na2CO3 + 2AgNO3 == Ag2CO?3 ↓ + 2NaNO3

Ag2CO?3 + 2HNO3 == 2AgNO3 + 2CONO3

Na2CO? = 2AgNO3 + CO2 ↑ + H2O

Cl- + Ag + == AgCl ↓

Eight, sulfur dioxide

Method (formation): sulfur yellow or sulfur-containing fuels burned to get (sulfur is commonly known as sulfur, is a yellow powder)

S + O2 === (ignition) SO2

Physical properties: colorless, irritating odor, easily liquefied, soluble in water (1:40 volume ratio)

Chemical properties: toxic, dissolved in water and water reaction to generate sulfurous acid H2SO3, the formation of the solution acidic, bleaching effect, will change back to its original color when heated. This is because H2SO3 is not stable, will decompose back to water and SO2

SO2 + H2O H2SO3 Therefore, this process of synthesis and decomposition can be carried out at the same time, for the reversible reaction.

Reversible reactions - chemical reactions that can occur both in the direction of a positive reaction and in the direction of a negative reaction under the same conditions are called reversible reactions, and are connected by a reversible arrow symbol.

Nine, nitric oxide and nitrogen dioxide

Nitric oxide is formed in nature under the condition of high temperature or discharge: N2 + O2 ======== (high temperature or discharge) 2NO, the generated nitric oxide is very unstable, and at room temperature, it will be synthesized into nitrogen dioxide when it meets with oxygen: 2NO + O2 == 2NO2

Nitrogen monoxide is introduced as a colorless gas, which is a pollutant in the air. air pollutant, a small amount of NO can treat cardiovascular disease.

Introduction of nitrogen dioxide: reddish brown gas, irritating odor, toxic, easily liquefied, soluble in water, and reacts with water:

3 NO2 + H2O == 2HNO3 + NO This is the industrial method of making nitric acid.

Ten, air pollution

SO2, NO2 dissolved in the rain to form acid rain. Preventive measures:

① From fuel combustion.

② from the legislative management.

3 from energy utilization and development.

④ Starting from the recycling of waste gas and turning harm into benefit.

(2SO2 + O2 2SO3 SO3 + H2O= H2SO4)

XI, sulfuric acid

Physical properties: colorless viscous oily liquid, non-volatile, high boiling point, density greater than water.

Chemical properties: with the general nature of the acid, concentrated sulfuric acid has dehydration, water absorption and strong oxidizing properties. It is a strong oxidizing agent.

C12H22O11 ======(Concentrated H2SO4) 12C + 11H2O exothermic

2 H2SO4 (Concentrated) + C CO2 ↑ + 2H2O + SO2 ↑

It also oxidizes the metals that rank behind hydrogen, but does not give off hydrogen.

2 H2SO4 (thick) + Cu CuSO4 + 2H2O + S02 ↑

Dilute sulfuric acid: reacts with active metals to emit H2, so that the acid-base indicator purple litmus red, reacts with certain salts, reacts with alkaline oxides, and alkaline neutralization

Twelve, nitric acid

Physical Properties: colorless liquid, volatile, boiling point is lower, the density is greater than water. greater than water.

Chemical properties: the general nature of the acid, concentrated and dilute nitric acid are strong oxidizing agent. Can also oxidize the metal behind the hydrogen, but does not give off hydrogen.

4HNO3 (concentrated) + Cu == Cu(NO3)2 + 2NO2 ↑ + 4H2O

8HNO3 (dilute) + 3Cu 3Cu(NO3)2 + 2NO ↑ + 4H2O

Reaction conditions are different, the nitric acid is reduced by the different products, there can be the following products:N(+4)O2,HN(+3)O2,N (+2)O,N(+1)2O,N(0)2, N(-3)H3△ sulfuric acid and nitric acid: concentrated sulfuric acid and concentrated nitric acid can passivate some metals (such as iron and aluminum) so that the surface to generate a dense layer of oxidized protective film, isolate the inner metal and acid, preventing further reactions. Therefore, iron and aluminum containers can hold cold concentrated sulfuric and nitric acid. Nitric acid and sulfuric acid are important chemical raw materials and important reagents necessary for the laboratory. They can be used to make fertilizers, pesticides, explosives, dyes, salts and so on. Sulfuric acid is also used for refining petroleum, metal processing before pickling and the production of a variety of volatile acids.

Thirteen, ammonia and ammonium salts

Properties of ammonia: colorless gas, irritating odor, density less than air, very soluble in water (and fast) 1:700 volume ratio. Dissolved in water, the following reactions occur to make the aqueous solution alkaline: NH3 + H2O NH3?H2O NH4 + + OH- can be made red fountain experiment. Generated ammonia monohydrate NH3?H2O is a weak base, very unstable, will decompose, heat is even more unstable: NH3?H2O === (△) NH3 ↑ ↑ + H2O

Concentrated ammonia is easy to volatile in addition to the ammonia gas, there is a stimulating and unpleasant odor.

Ammonia can react with acid to produce ammonium salt: NH3 + HCl == NH4Cl (crystals)

Ammonia is an important chemical product, nitrogen fertilizer industry, the organic synthesis industry and the manufacture of nitric acid, ammonium salts and soda ash are indispensable to it. Ammonia is easily liquefied into liquid ammonia, which absorbs a large amount of heat when it is vaporized, so it can also be used as a refrigerant. NH4NO3 + NaOH Na NO3 + H2O + NH3 ↑

2NH4Cl + Ca(OH)2 CaCl2 + 2H2O + 2NH3 ↑

Collected by downward air exhaustion, and red litmus paper to test whether it is collected to full.