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Anonymous users2024-02-06Displacement reaction: A+BC=Ca+B, the requirement is that the elemental activity of A is stronger than that of B, otherwise the reaction cannot be performed.
Elemental activity table: k ca na mg al zn fe sn pb (h) cu hg ag pt au
If the metal reacts with the salt, the salt must be a solution.
If the metal is k ca na, it cannot react.
Metathesis reaction.
There are two conditions for whether ab+cd=ad+bc can react.
1.Inside the product there is water, gas or one of the precipitates.
2.If it's salt-to-salt, salt-to-alkali reaction (you should know what this is.) I don't know to send me a message) must be 2 of them are solutions, otherwise they can't react.
See if it is precipitation 1 is the usual accumulation 2It is possible to read a substance solubility table (to be memorized) at the back of a science book
The displacement reaction has elemental participation and elemental generation.
The metathesis reaction only participates in the reaction and only the compounds are generated.
Redox reactions.
A type of reaction that reduces metal oxides to metal elements by losing oxygen.
Generally, there are oxidizing agents and reducing agents.
The valency increases to get oxygen and it is the reducing agent that participates in the oxidation reaction.
Reduced valency Loss of oxygen It is the oxidant (the original oxygen element in it) that participates in the reduction reaction
The chemical reaction of the acid-base reaction is called the neutralization reaction. It is a type of metathesis reaction.
Its essence is that the anions (hydroxides) in the alkali and the cations (hydrogen) in the calculation are combined to form water.
Acid: A substance that ionizes all cations with H+ is called acid.
1.Reacts with metal oxides.
2.It reacts with metals to produce hydrogen. Pay attention to the elemental activity table. If it is less than H, it cannot be reacted, and if it is iron, it is ferrous (iron is formed in the displacement reaction).
3.Neutralize with alkali.
4.React with salt.
5.Reacts with acid-base indicators.
Alkali: After ionization, all anions are oh- substances.
1.Reacts with acid-base indicators.
2.It reacts with acid to form salt + water.
3.It reacts with non-metallic oxides (this is not hydrous into acid, such as: SO3 + H2O = H2SO4).
4.React with the salt solution (it must be a solution, otherwise it cannot react).
Salt: The combination of metal or ammonia cation and acid anion is called salt.
1.The salt solution reacts with the metal to form a new metal + a new salt (note: it must be a solution and pay attention to the elemental activity).
2.Salt + acid.
3.Salt solution + alkaline solution (both are solutions).
4.Salt solution + salt solution generates new salt + new salt.
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Anonymous users2024-02-05(1) Physical change: There is no change in the formation of new matter.
No new matter is formed macroscopically, and no new molecules are formed on the microscopic level.
It often refers to a change in the state of matter, a change in shape, a shift in position, etc.
For example: the change of the three states of water, the volatilization of gasoline, the sublimation of dry ice, the making of wood into tables and chairs, the breaking of glass, and so on.
(2) Chemical change: There is a change in the formation of new substances, also called chemical reactions.
New substances are formed on the macroscopic level and new molecules are formed on the microscopic level.
Chemical changes are often accompanied by some reaction phenomena, such as luminescence, heat generation, gas production, color change, precipitation, etc. In some cases, reaction phenomena can be used to determine whether a chemical change has occurred or what kind of substance the product is.
(3) Physical properties: the properties of substances that can be exhibited without chemical changes.
Physical properties are not properties that manifest themselves only when matter undergoes physical changes; For example:
Wood has a dense nature and does not require it to change shape before it manifests itself.
The physical properties perceived by the senses mainly include: color, state, smell, etc.
The physical properties that need to be determined by instruments are: melting point, boiling point, density, hardness, dissolution growth, conductivity, etc.
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Anonymous users2024-02-041. Smoke: solid small particles. Mist: Small droplets. Smoke: There are both small particles and small droplets.
2. Chemical formula: The formula that expresses the composition of matter with element symbols. (Represents a substance) Chemical Equation: A formula that represents a chemical reaction with a chemical formula. (indicates a specific chemical reaction).
3. The three particles that make up atoms: protons, neutrons, and electrons; There are three types of particles that make up matter: molecules, atoms, and ions.
1) denotes a certain element; (2) represents an atom of such an element; (3) Symbols of noble gas elements and metal elements can also represent substances. Note: The number preceded by the element symbol only indicates the number of atoms.
The example "2h" represents only 2 hydrogen atoms. (4) Indicates the number of atoms contained in a molecule of the substance. Note:
The number in front of the chemical formula only indicates the number of molecules. For example, "2H2O" represents only 2 water molecules. (2) The reaction of 4 parts of hydrogen and 32 parts of oxygen can produce 36 parts of water.
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Anonymous users2024-02-031. Chemical changes and physical changes.
2. Chemistry and procedures.
3. The concept of the four basic types of reactions.
4. The law of conservation of mass.
5. Atom, proton, neutron, electron and extranuclear electron configuration.
Why it has to be"A certain amount of solvent"At a certain temperature, it dissolves to the point that it is insoluble, and it is a saturated solution. You're right. Emphasis"A certain amount of solvent"First, according to the actual situation, our saturated solution is always configured in a certain amount of solvent, and second, the saturated solution also has a concept of saturation, which needs to be emphasized in "a certain amount of solvent".
The third junior high school chemistry teaching plan courseware old Peng family and the Shen family have a bit of in-law relationship, Xiao Peng is a famous university scholar, so Shen Deqian compiled "Ancient Poetry Source" and the poetry of the past dynasties, reluctantly wanted to discuss a few words with him, but Xiao Peng did not want to leave a name, he knew that some well-behaved could not be made, but it also allowed him to avoid the fate of being "slammed on the monument" after death. The name of the garden looks simple, it is not easy to blurt out and explain clearly, such a name still has to be said word by word, first say the word "net", naturally it is the fishing net of the fisherman's family, the borrowed meaning is probably this meaning, and the "teacher" should be a person who has mastered a certain skill, and it is probably a flaunt of his own retreat. In fact, this is a cliché, because the Master of Nets Garden has the alias of "Yuyin" early on. >>>More
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1. The smell of burnt feathers.
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