1, chemistry is the study of the composition of matter, structure, nature and the law of change of the basic science.
2, China's working people will make bronze in the Shang Dynasty, the Spring and Autumn and Warring States will be iron and steelmaking.
3, green chemistry ----- environmentally friendly chemistry (chemical reactions in line with green chemistry)
① four features P6 (raw materials, conditions, zero emissions, products) ② core: the use of chemical principles to eliminate pollution from the source
4, candle combustion experiments (describing the phenomenon can not appear product name)
(1) flame: flame center, inner flame (the brightest), outer flame (the most bright). (the brightest), the outer flame (the highest temperature)
(2) Comparison of the temperature of each flame layer: a matchstick flat into the flame. Phenomenon: the ends of the first carbonization; Conclusion: the highest temperature of the outer flame
(3) the test product H2O: a dry cold beaker cover the flame above the beaker of water mist
CO2: remove the beaker, pour into the clarified lime water, oscillation, cloudy
(4) extinguished: there is a white smoke (for the paraffin vapors), light the white smoke, the candle rekindled. Explain paraffin vapor combustion.
5. Comparison of inhaled air and exhaled gas
Conclusion: Compared with inhaled air, the amount of O2 in the exhaled gas is reduced, and the amount of CO2 and H2O is increased
(the composition of the inhaled air and exhaled gas is the same)
6. Important ways to learn chemistry - Scientific inquiry
General steps: raising questions → conjectures and hypotheses → designing experiments → experimental verification → records and conclusions → reflection and evaluation
Characteristics of chemical learning: focus on the nature of substances, changes, the process of change and its phenomena;
7, chemical experiments (Chemistry is an experimental-based science)
I. Commonly used instruments and methods of use
(i) Instruments used for heating - test tubes, beakers, flasks, evaporating dishes, conical flasks
Instruments that can be heated directly are - test tubes, evaporating dishes, burning spoons
Instruments that can be heated only indirectly are --Beaker, flask, conical flask (lined with asbestos mesh - heated uniformly)
Instruments that can be used for heating solids are -- Test tube, evaporating dish
Instruments that can be used for heating liquids are - test tubes, beakers, evaporating dishes, flasks, conical flasks
Instruments that cannot be heated - measuring cylinders, funnels, collecting cylinders
(ii) Measuring vessels - Measuring cylinder
When measuring the volume of a liquid, the measuring cylinder must be placed smoothly. The line of sight is level with the scale and the lowest point of the concave surface of the liquid in the cylinder.
The measuring cylinder cannot be used for heating or as a reaction vessel. A cylinder with a 10-milliliter range can usually only be read to 0.1 milliliter.
(iii) Weighing Instrument - Pallet Balance (Used for rough weighing, generally capable of accuracy to 0.1 grams.)
Note: (1) first adjust the zero point
(2) the position of the weighing object and weights for the "left object right code".
(3) Weighing objects can not be placed directly on the tray.
General medicine weighing, in both sides of the tray on each side of a piece of paper of the same size and quality, weighing on the paper. Moist or corrosive drugs (e.g., sodium hydroxide) are weighed in covered glassware (e.g., small beakers, surface dishes).
(4) Weights are taken with tweezers. When adding weights, add the weights with larger mass first, and then add the weights with smaller mass (first larger and then smaller)
(5) After weighing, the vernier should be zeroed. The weights are put back to the weight box.
(D) heating vessels - alcohol lamp
(1) the use of alcohol lamps should pay attention to the "three nots": ① not to add alcohol to the burning alcohol lamp; ② match from the side of the alcohol lamp lit, not with a burning alcohol lamp directly ignite another alcohol lamp; ③ extinguish the alcohol lamp should be covered with a cap off, do not blow out.
(2) The amount of alcohol in the alcohol lamp should not exceed 2/3 of the volume of the alcohol lamp should not be less than 1/4.
(3) The flame of the alcohol lamp is divided into three layers, the outer flame, the inner flame, the center of the flame. The outer flame of the lamp is used to heat the object.
(4) If the alcohol lamp is inadvertently tipped over while burning, and the alcohol burns on the lab bench, the flame should be extinguished in time by covering it with sand or extinguishing it with a wet rag, and should not be flushed with water.
(E) grippers - iron clamps, test tube clamps
The position of the iron clamps to hold the test tubes should be nearly 1/3 of the test tube mouth. The test tube clamp has a long handle, do not press your thumb on the short handle.
The test-tube clamp should be set from the bottom of the test-tube upwards when the test-tube is clamped; the clamping part should be nearly 1/3 from the mouth of the test-tube; hold it with your hand
(F) Instruments for separating substances and adding liquids - funnel, long-necked funnel
When filtration is carried out, the lower end of the funnel's spout and the inside of the beaker to be undertaken should be made to be close to one another to avoid splashing of the filtrate. to avoid splashing of the filtrate.
The lower spout of the long-necked funnel should be inserted below the liquid level to prevent the gas generated from escaping from the mouth of the long-necked funnel.
Basic operation of chemical experiments
(a) access to medicines
1, the storage of medicines:
general solid medicines in wide-mouth bottles, liquid medicines in fine-mouth bottles (a small amount of liquid medicines can be placed in a dropper bottle),
metal sodium in kerosene, white phosphorus is stored in water
2, the general principle of access to medicines The general principle
①Take the amount: according to the experimental need to take drugs. If there is no indication of the amount, should take the smallest amount of solid to cover the bottom of the test tube is appropriate,
(2) air pollution and prevention: air pollution is mainly caused by harmful gases (CO, SO2, nitrogen oxides) and soot and so on. The items currently counted in the air pollution index are CO, SO2, NO2, O3 and respirable particulate matter.
(3) air pollution hazards, protection:
Hazards: serious damage to human health, affecting crop growth, and destroying the ecological balance. Global warming, destruction of the ozone layer and acid rain, etc.
Protection: strengthen the monitoring of the quality of the atmosphere, improve the environmental situation, use clean energy, exhaust gas from factories can only be discharged after treatment, and actively plant trees, forests, grasses, etc.
(4) The current environmental pollution problems:
Destruction of the ozone layer (Freon, nitrogen oxides, etc.) Greenhouse effect (CO2, CH4, etc.)
The greenhouse effect is a major cause of air pollution. (CO2, CH4, etc.)
Acid Rain (NO2, SO2, etc.) White Pollution (Plastic Waste, etc.)
6. Oxygen
(1) Chemical Properties of Oxygen: Specific Properties: Supports Combustion, Supplies for Breathing
(2) Oxygen Reacts to the Following Phenomena
Substances Phenomena
Carbon Remains red-hot in air, emits a white light, produces a light that makes a clear, bright light in oxygen, and produces a light that makes a clear, bright light in oxygen. emits white light and produces a gas that makes clarified lime water cloudy
phosphorus produces a lot of white smoke
sulfur emits a weak light blue flame in air and a bright blue-purple flame in oxygen
produces a gas with a pungent odor
magnesium emits a bright white light, releases heat, and produces a white solid
aluminum
Iron burns vigorously and the flame is hot, and the fire is very hot. p>Iron burns fiercely, sparks fly in all directions, producing a black solid (Fe3O4)
Paraffin burns in oxygen and emits a white light, beads of water on the walls of the bottle, and produces a gas that makes the clarified lime water cloudy
*The purpose of putting a small amount of water or fine sand at the bottom of the cylinder for iron and aluminum combustion is to prevent the spattering of the hot melted material from blowing the bottom of the cylinder
*Iron and aluminum cannot be combusted in air. cannot be burned.
(3) Preparation of oxygen:
Industrial production of oxygen - separation of liquid air method (principle: nitrogen and oxygen have different boiling points physical changes)
Laboratory production of oxygen principle 2H2O2 MnO2 2H2O + O2↑
2KMnO4 △ K2MnO4 + MnO2 + O2↑
2KClO3MnO22KCl+3O2↑
(4) the choice of gas production and collection device △
generation device: solid-solid heating, solid-liquid heating type, the collection device: according to the density of the substance, the solubility
(5) the operation of the production of oxygen and points to note (in order to) Potassium permanganate to produce oxygen and collected by drainage method as an example)
a, steps: check - load - set - point - collect - move - extinguish
b, points of attention
①The mouth of the test tube tilted slightly downward: to prevent condensate backflow caused by the rupture of the test tube
②The drug is laid flat at the bottom of the test tube: even heat
③The iron clip is clamped at the mouth of the tube about 1/3
④The catheter should be slightly exposed to the rubber stopper: to facilitate the discharge of gases
5The mouth of the test tube should be placed in a ball of cotton: to prevent the potassium permanganate powder from entering the catheter
⑥Drainage method of collecting
⑤The mouth of the test tube should be placed a piece of cotton: to prevent the potassium permanganate powder from entering the tube
⑥When collecting by the drainage method, collect the bubbles when they come out uniformly and continuously (the air is discharged from the test tube at the beginning)
⑦At the end of the experiment, move the tube and then extinguish the alcohol lamp: to prevent water from attracting the rupture of the test tube
⑧To collect the gases by the exhaust gas method, the tube is stretched out to the bottom of the cylinder
(6) the fullness of the test for oxygen: put the wooden bar with the sparks on the mouth of the cylinder
Test: with a spark of wood into the cylinder
7, catalyst (catalyst): in a chemical reaction can change the rate of other substances in the chemical reaction, and its own quality and chemical
properties before and after the reaction have not changed the substance. (One change, two no changes)
The role played by a catalyst in a chemical reaction is called catalysis.
8, the use of common gases:
① oxygen: for breathing (such as diving, medical emergencies)
support combustion (such as fuel combustion, steelmaking, gas welding)
② nitrogen: inert protective gas (chemical inactivity), important raw materials (nitric acid, fertilizer), liquid nitrogen refrigeration
③ rare gases (He, Ne, Ar, Kr, Xe, etc.):
protective gas, electric light (electrified light of different colors), laser technology
9, the test of common gases
① Oxygen: a wooden stick with sparks
② carbon dioxide: clarified lime water
3 hydrogen: the gas will be ignited, with a dry and cold beaker over the flame;
Or, first through the burning copper oxide, and then through anhydrous copper sulfate
9, oxidation reaction: chemical reaction of substances with oxygen (elemental oxygen).
violent oxidation: combustion
slow oxidation: iron rust, human respiration, things rot, wine brewing
***same point: ① are oxidation reactions ② are exothermic
Unit 3, "Water in Nature" Knowledge Points
I. Water
1, the composition of water:
(1) experiments on electrolysis of water < /p>
A. Device - water electrolyzer
B. Type of power source - direct current
C. Purpose of adding sulfuric acid or sodium hydroxide ---- to enhance the electrical conductivity of water
D. Chemical reaction: 2H2O=== 2H2↑+ O2↑
Generation position Negative pole Positive pole
Volume ratio 2 : 1
Mass ratio 1 : 8
F.Tests: O2 - a wooden bar with a spark at the outlet ---- The wooden bar rekindles
H2 - a burning wooden bar at the outlet ------ The gas burns and produces a light blue flame
(2) Conclusion: ① Water is composed of the elements hydrogen and oxygen.
② A water molecule is composed of two hydrogen atoms and one oxygen atom.
③ In chemical changes, molecules are separable but atoms are not.
Example: According to the chemical formula H2O for water, you can read the information
Meaning of the chemical formula H2O
①Indicates a substance, water, as a substance
②Indicates the composition of this substance, water, which is composed of the elements hydrogen and oxygen
③Indicates the composition of a molecule, a molecule of water
④Indicates that a molecule, a molecule of water, is composed of a molecule of water
4Indicates that a molecule of water is composed of a molecule of water
5 A water molecule is composed of two hydrogen atoms and one oxygen atom
2, the chemical properties of water
(1) decomposition of electricity 2H2O=== 2H2↑ + O2↑
(2) water can be met with certain oxides to form bases (soluble bases), for example: H2O + CaO== Ca(OH)2
() (3) Water can react with certain oxides to form acids, e.g., H2O + CO2==H2CO3
3. Water Pollution:
(1) Water Resources
A. 71% of the earth's surface is covered by water, but less than 1% of the fresh water is available for human use
B. The oceans and seas are the largest reservoirs of water on earth. Seawater contains more than 80 elements. The most abundant substance in seawater is H2O, the most abundant metallic element is Na, and the most abundant element is O. The most abundant element in seawater is O.
C. China's water resources are unevenly distributed, and the per capita amount is small.
(2) water pollution
A, water pollutants: industrial "three wastes" (slag, waste liquids, waste gas); pesticides, fertilizers, the irrational application of
arbitrary discharge of sewage
B, to prevent water pollution: industrial waste should be processed to meet the standards of discharge, and advocate the zero discharge; Domestic sewage should be centrally treated and discharged up to standard, and zero discharge is advocated; rational application of pesticides and fertilizers, and the use of farmyard manure is advocated; and the monitoring of water quality is strengthened.
(3) care for water resources: water conservation, to prevent water pollution
4, water purification
(1) water purification effect from low to high is the static, adsorption, filtration, distillation (all physical methods), which purifies the best operation is the distillation; both filtration and adsorption of water purification agent is activated carbon.
(2) hard water and soft water
A. Definition Hard water is water that contains more soluble calcium and magnesium compounds;
Soft water is water that does not contain soluble calcium and magnesium compounds or contains less.
B. Identification: soapy water, scum or less foam is hard water, more foam is soft water
C. Methods of softening hard water: distillation, boiling
D. Long-term use of hard water disadvantages: a waste of soap, washing clothes; boilers are easy to scale, not only a waste of fuel, but also prone to deformation of the pipeline and even cause boiler explosions.
5. Others
(1) Water is one of the most common solvents and is the oxide with the smallest relative molecular mass.
(2) water test: use anhydrous copper sulfate, if from white to blue, indicating the presence of water; CuSO4 + 5H2O = CuSO4?5H2O
Water absorption: commonly used concentrated sulfuric acid, quicklime, solid sodium hydroxide, iron powder.
Two, hydrogen H2
1, physical properties: the least dense gas (downward air exhaust method); insoluble in water (drainage method)
2, chemical properties:
(1) flammability (use: high-energy fuels; hydroxide flame welding, cutting metal)
2H2 + O2 ====2H2O before ignition, to test the purity of (method) (method?)
Phenomenon: light blue flame, heat, water droplets
(2) reductivity (use: smelting metals)
H2 ＋ CuO === Cu + H2O Hydrogen "early and late"
Phenomenon: black powder becomes red, the mouth of the test tube beads of water generation
(Summary: both flammable and reducing substances H2, C, CO)
3, hydrogen laboratory method
Principle: Zn + H2SO4 = ZnSO4 +H2↑ Zn + 2HCl = ZnCl2 +H2↑
Not to be used with concentrated hydrochloric acid reasons Concentrated hydrochloric acid has a strong volatility;
Not to be used. Concentrated sulfuric acid and nitric acid have strong oxidizing properties.
4, hydrogen energy, three major advantages of non-polluting, high heat release, wide range of sources
Three, molecules and atoms
Molecules Atoms
Definition Molecules are the smallest particles to maintain the chemical properties of substances Atoms are the smallest particles of chemical change.
Properties Small size and mass; constant motion; interstices
Connections Molecules are made of atoms. Molecules and atoms are the particles that make up matter.
Difference In chemical change, molecules are separable, atoms are not.
Substance of a chemical reaction: in a chemical reaction molecules split into atoms and atoms recombine to form new molecules.
Four, the composition of matter, composition and classification
Composition: matter (pure matter) consists of elements
Atoms: metals, rare gases, carbon, silicon and so on.
Substances Composition Molecules: e.g. hydrogen chloride consists of hydrogen chloride molecules. H2, O2, N2, Cl2.
Ions : Ionic compounds like NaCl, e.g., sodium chloride consists of sodium ions (Na+) chloride ions (Cl-)
Mixtures (multiple substances)
Classification Monomers : Metals, nonmetals, rare gases
Pure substances (one element)
(one substance) Compounds: Organic compounds CH4, C2H5OH, C6H12O6, starch, proteins (multiple elements)
Oxides H2O CuO CO2
Inorganic compounds Acids HCl H2SO4 HNO3
Alkalis NaOH Ca(OH)2 KOH
Salts NaCl CuSO4 Na2CO3
< p>Unit IV The Mystery of the Composition of Matter Review1, the composition of atoms
(1) atomic structure schematic understanding
(2) in the atom nuclear charge = protons = number of electrons outside the nucleus determines the type of element proton number (nuclear charge)
(3) the mass of the atom is concentrated in the nucleus of the atom (4) the three decisions determines the elements Chemical properties Number of electrons in the outermost layer
(4) Relative atomic mass ≈ number of protons + number of neutrons Determine the mass of the atom Atomic nucleus
Explanation: the same number of electrons in the outermost layer of the same chemical properties are not necessarily the same (Mg, He the number of electrons in the outermost layer of the 2)
the different number of electrons in the outermost layer of the different chemical properties are likely to be similar (He, Ne are stable)
2.
2, elements
(1) definition: a class of atoms with the same nuclear charge (number of protons) of the general term
* an element and another element of the essential difference: the number of protons is different
Note:
* by the same elements of the substance is not necessarily a single substance, (such as O2, O3 mixture or diamond and graphite mixture) can not be compounds. ) It cannot be a compound.
(2) Representation - Symbol of an element - the first letter of the Latin name capitalized
a, writing:
b, meaning
Note: *Some symbols of elements can also represent A single substance, such as Fe, He, C, Si
* in the element symbols before the addition of numbers can only have a microscopic significance, there is no macroscopic significance, such as 3O: only three oxygen atoms
c, the periodic table
* Discovery: Mendeleev
* Arrangement of the basis
*Note: Atomic number = the number of protons
d Classification
e, the most elements: crust: O, Si, Al, Fe cells: O, C, H
3, ions: electrically charged atoms or clusters of atoms
(1) Representation and significance: For example, Fe3 +: an iron ion with a 3-unit positive charge
(2) Recognition of the structure of ions schematic
Note: and atomic Schematic diagram of atomic structure
*Atomic number ≠ electron number for ionic structure
(3) Differences and connections with atoms
Types of particles Atoms Ions
Cations Anions
Cations Anions
Districts
Differences between particle structures Proton number = Electron number Proton number > Electron number Proton number <. number of protons number of protons<electrons
Particle electrical properties Not electrically significant Positively significant Negatively significant
Symbols Expressed in elemental symbols Expressed in cation symbols Expressed in anion symbols
II. Expression of composition of substances:
1. Compound valence
a. Write and significance: Mg: Magnesium elemental compound valence is +2 valence MgCl2: Magnesium chloride in the magnesium element with a valence of +2
b, the meaning of several numbers
Fe2+ Each ferrous ion has a two-unit positive charge 3 Fe2+: 3 ferrous ions
2H2O Two molecules of water, each water molecule contains 2 atoms of hydrogen
c, compounds in which the algebraic sum of the positive and negative valences of the elements is zero
d, valency is the element of the atoms in the formation of compounds when the performance of the nature, so the molecules of monomers in the element valency is 0
2, chemical formula
(1) write:
a monomers: metals, rare gases and most solid non-metals are usually used to indicate the symbols of the elements in their chemical formulas; oxygen, hydrogen, nitrogen, chlorine and other non-metallic gases such as molecular consists of two atoms, and their chemical formulas are expressed as O2, H2, N2, Cl2 .
b compounds: positive valence in the front, negative valence in the back (except NH3, CH4)
(2) meaning: such as the meaning of the chemical formula H2O: 4 points chemical formula Fe: 3 points
(3) calculations:
a, calculating the relative molecular mass = the relative atomic mass of each element × the sum of the number of atoms
b, calculating the substance The mass ratio of the constituent elements: relative atomic mass × the ratio of the number of atoms
c. Calculate the mass fraction of an element in a substance
Unit 5 "Chemical Equations" Knowledge Points
I. The Law of Conservation of Mass:
1. Contents: The sum of the mass of each substance participating in a chemical reaction is equal to the sum of the mass of each substance produced after the reaction.
Note: ① the law of conservation of mass applies only to chemical changes, does not apply to physical changes;
② the mass of substances that do not participate in the reaction and the mass of substances that are not products can not be counted in the "sum";
③ to take into account whether or not the substances in the air to take part in the reaction or the substances (such as gases) There are no omissions.
2, microscopic explanation: before and after the chemical reaction, the type, number and mass of atoms remain unchanged (atomic "three invariant").
3, before and after a chemical reaction (1) must remain the same macro: the total mass of the reactants and products remains the same; the type and mass of the elements remain unchanged
micro: the type, number and mass of atoms remain unchanged
(2) must change macro: the type of substance must change
micro: the type of molecules must change
(3) may change: the total number of molecules may change
Two, chemical equations
1, follow the principle: ① based on objective facts ② comply with the law of conservation of mass
2, writing: (Note: a, leveling b, conditions c, arrows)
3, meaning 2H2 + O2 ignition of 2H2O as an example
① Macro significance: indicates that the reactants, products, reaction
1 macro significance: indicates that the reactants, products, reaction
3, meaning of hydrogen and oxygen in the ignition of hydrogen and oxygen. conditions Hydrogen and oxygen in the ignition conditions to produce water
② microscopic significance: indicates that the reactants and products between the molecules of every 2 hydrogen molecules and 1 oxygen molecules to produce 2
(or atoms) than the number of molecules of water
(for gases, molecular ratio is equal to the ratio of the volume of the molecules)
③ the mass of each substance than the ratio (coefficient × relative molecular mass) of the ratio of every four mass The ratio of the mass of each substance (coefficient × relative molecular mass) Every 4 parts of the mass of hydrogen and 32 parts of the mass of oxygen are completely combined to produce 36 parts of the mass of water
4, chemical equations provide information, including
①which substances take part in the reaction (reactant); ② by what conditions the reaction: ③ reaction of the substances produced by the reaction (product); ④ the relative number of particles participating in the reaction; ⑤ before and after the reaction of the mass of the conservation of, and so on.
5, the use of chemical equations
Three, types of chemical reactions
1, the four basic types of reactions
①Chemistry: two or more substances from two or more substances to generate another reaction
② decomposition: a reactant from a reaction to generate two or more other substances reacted
3 substitution reaction: a monomer and a compound reaction, the generation of another monomer and another compound reaction
④ complex decomposition reaction: two compounds exchanged for each other to generate two other compounds reaction
2, redox reaction
oxidation: the reaction of the substance to get the oxygen reaction
reduction: the reaction of the substance to lose the oxygen
Oxidizing agent: a substance that provides oxygen
Reducing agent: a substance that takes away oxygen (common reducing agents: H2, C, CO)
3, neutralization: the reaction in which an acid acts with a base to produce a salt and water
Unit 6: Carbon and Carbon Oxides
A. Carbon Monomers
1. Diamond (C) is the hardest substance in nature. , which can be used to make diamonds, etched glass, drill bits for drilling machines, etc.
2, graphite (C) is one of the softest minerals, has excellent electrical conductivity, lubrication. Can be used to make pencil lead, electrodes for dry cell batteries, sliders for trolley cars, etc.
The reason for the great difference in the physical properties of diamond and graphite is that the arrangement of carbon atoms is different.
The chemical properties of CO and CO2 are very different because of the different composition of the molecules.
3, amorphous carbon: graphite by the tiny crystals and a small number of impurities. Mainly: coke, charcoal, activated carbon, carbon black and so on.
Activated charcoal, charcoal has a strong adsorption, coke is used for iron smelting, carbon black added to the rubber can increase the wear resistance of tires.
Two. Chemical Properties of Monomeric Carbon:
The physical properties of monomeric carbon vary, while the chemical properties of various monomers are exactly the same!
1, strong stability at room temperature
2, flammability:
complete combustion (oxygen is sufficient), the generation of CO2 : C + O2 ignition of CO2
Incomplete combustion (oxygen is not sufficient), the generation of CO: 2C + O2 ignition of 2CO
3, reductivity: C + 2CuO high temperatures 2Cu + CO2 ↑ (replacement) reaction. (Reaction) Application: metallurgical industry
Phenomenon: black powder gradually become bright red, lime water becomes turbid.
2Fe2O3 + 3C high temperature 4Fe + 3CO2↑
Three, carbon dioxide production
1, the laboratory gas production ideas: (principle, device, test)
(1) the occurrence of the device: by the state of the reactant and the reaction conditions:
Reactant is a solid, the need to be heated, the production of gas, then use potassium permanganate O2 generation device.
The reactants are solid and liquid, do not need to be heated, the production of gas is used in the production of H2 generator.
(2) collection method: the density and solubility of the gas decided:
difficult to dissolve in water with the drainage method to collect CO can only be used with the drainage method
density than the air with the upward air method CO2 can only be used with the upward air method
density than the air is smaller than the downward air method
2, carbon dioxide laboratory method
1) principle: the reaction of limestone and dilute hydrochloric acid: CaCO3 + 2HCl === CaCl2 + H2O + CO2↑
2) choose and hydrogen production of the same generator
3) gas collection method: upward exhaust method
4) verification method: the gas will be produced by passing into the clarified lime water, such as can be turbid, then it is carbon dioxide.
Method of checking the fullness: use a lighted wooden bar, put it on the mouth of the gas collecting cylinder, the bar goes out. Prove that it is full of carbon dioxide gas.
3, carbon dioxide industrial method:
calcined limestone: CaCO3 high temperature CaO + CO2 ↑
lime and water reaction can be slaked lime: CaO + H2O = Ca (OH) 2
four, carbon dioxide properties
1, physical properties: colorless, odorless gas, density greater than air, can be dissolved in water. dissolved in water, high pressure and low temperature can be solid ---- dry ice
2, chemical properties:
1) generally can not be burned, and does not support combustion, can not be supplied to the respiratory
2) and water to generate carbonic acid: CO2 + H2O == H2CO3 carbonic acid can make the purple litmus test solution red,
H2CO3 == H2O+ CO2↑ carbonic acid does not make red,
H2CO3 == H2O+ CO2↑ carbonic acid can not make red,
H2CO3 == H2O+ CO2↑ carbonic acid is not a good choice. H2O+ CO2↑ Carbonic acid is unstable, easy to decompose
3) can make the clarified lime water turbid: CO2 + Ca (OH) 2 == CaCO3 ↓ + H2O This reaction is used to test carbon dioxide.
4) and burning carbon reaction: C + CO2 high temperature 2CO
(heat-absorbing reaction, both chemosynthesis and redox reaction, CO2 is an oxidizing agent, C is a reductant)
3, use: fire extinguishing (Fire Extinguisher Principle: Na2CO3 + 2HCl == 2NaCl + H2O + CO2 ↑)
both the use of its Physical properties, but also use its chemical properties
Dry ice is used for artificial rainfall, refrigerants
Greenhouse fertilizer
4, carbon dioxide multi-environmental impact: too much emission caused by the greenhouse effect.
5, carbon monoxide
1, physical properties: colorless, odorless gas, slightly less dense than air, insoluble in water
2, poisonous: sucked into the lungs and blood hemoglobin combination, so that the body lacks oxygen and poisoning.
3, chemical properties: (H2, CO, C has similar chemical properties: ① flammability ② reduction)
1) flammability: 2CO + O2 ignition 2CO2 (combustible gases must be tested for purity before ignition)
H2 and O2 combustion flame is: emit light blue flame.
CO and O2 burn with a blue flame.
CH4 and O2 burn with: a bright blue flame.
Identification: H2, CO, CH4 flammable gases: look at the products of combustion (not based on the color of the flame)
(water gas: H2 and CO mixture of gases C + H2O high temperature H2 + CO)
2) Reduction: CO + CuO △ Cu + CO2 (non-replacement reaction) Application: Metallurgy
Phenomenon: black Copper oxide gradually becomes bright red, lime water becomes turbid.
Fe2O3+3CO high temperature 2Fe+3CO2 (Phenomenon: reddish brown powder gradually becomes black, lime water becomes turbid.)
Demixing: CO[CO2] pass into lime water or sodium hydroxide solution: CO2+2NaOH==Na2CO3+H2O
CO2[CO] pass through the burning copper oxide CO+CuO △ Cu+CO2
CaO[CaCO3] can only be calcined (can not be added to the hydrochloric acid) CaCO3 high temperature CaO+CO2↑ < /p>
Note: test whether CaO contains CaCO3 plus hydrochloric acid : CaCO3 + 2HCl == CaCl2 + H2O + CO2 ↑
(CO32- test: first add hydrochloric acid, and then the resulting gas is passed through clarified limewater.)
Unit 7 Combustion and Its Utilization
I. Combustion and Fire Extinguishing
1, the conditions of combustion: (one or the other is missing)
(1) combustible material (2) oxygen (or air) (3) the temperature reaches the point of ignition
2, the principle of extinguishing the fire: (as long as the elimination of combustion conditions of any of the can be)
(1) eliminating the Combustible material (2) isolation of oxygen (or air) (3) cooling to below the ignition point
3, factors affecting the phenomenon of combustion: the nature of combustible materials, the concentration of oxygen, and the contact area of oxygen
The two conditions to make the fuel fully combustible: (1) there should be a sufficient amount of air
(2) the fuel and the air have a large enough contact area.
4, explosion: combustible material in a limited space burning rapidly, the rapid expansion of gas volume and cause an explosion.
All combustible gases, combustible liquids vapor, combustible dust and air (or oxygen) mixture may explode when fire.
Two, fuel and energy
1, the three major fossil fuels: coal, oil, natural gas (mixture, are non-renewable energy sources)
(1) Coal: "food for industry" (mainly containing carbon);
coal combustion emissions of pollutants: SO2, NO2 ( causes acid rain), CO, soot, etc.
(2) oil: "blood of industry" (mainly containing carbon and hydrogen);
Pollutants in car exhaust: CO, unburned hydrocarbons, oxides of nitrogen, lead compounds and soot
(3) natural gas is a gaseous fossil fuel (main component: methane), is a cleaner energy source.
2, two green energy: biogas, ethanol
(1) the main component of biogas: methane
Methane's chemical formula: CH4 (the simplest organic matter, the smallest relative molecular mass of the organic matter)
Physical Properties: colorless, odorless gas, density is smaller than air, very difficult to dissolve in water.
Chemical properties: combustibility CH4+2O2 ignites CO2+2H2O (blue flame)
(2) Ethanol (commonly known as: alcohol, chemical formula: C2H5OH)
Chemical properties: combustibility C2H5OH+ 3O2 ignites 2CO2+3H2O
Industrial alcohol often contains toxic methanol, so it can't be used as alcohol. CH3OH, so you can't use industrial alcohol to prepare wine!
Ethanol gasoline: Advantages (1) saving petroleum resources (2) to reduce vehicle emissions
(3) to promote agricultural development (4) ethanol can be regenerated
3, chemical reactions in the change of energy
(1) exothermic reactions: such as all the combustion
(2) absorptive reactions: such as C + CO2 high temperature 2CO
4, new energy: hydrogen energy, solar energy, nuclear energy, wind energy, geothermal energy, tidal energy
Hydrogen is the most ideal fuel:
(1) Advantages: abundant resources, more heat release, no pollution.
(2) need to solve the problem: ① how to produce hydrogen in large quantities and cheaply? ② How to safely transport and store hydrogen?