The difference between symbolic expressions and chemical equations

The differences are as follows: 1. The symbols are different.

Symbolic expressions are used with the chemical formula of a substance with "+"."→"does not need to be marked with a gas symbol or a precipitation symbol.

The chemical equation is the chemical formula of the substance with "+"."="When there is gas or precipitation in the product, the gas symbol or precipitation symbol should be marked on the right side of the product.

2. Whether it is trimmed.

Symbolic expressions do not need to be trimmed.

Chemical equations need to be balanced on the basis of expressions and need to obey the law of conservation of mass.

For example, red phosphorus burns:

1. Symbolic expression: write "ignite" on the arrow;

2. Chemical equation: write "ignition" on the equal sign.

Extended information: Calculations based on chemical equations.

The chemical equation not only indicates what substances participate in the reaction and what substances are formed after the reaction, but also the mass ratio between the reactants and the resulting substances.

Calculations according to chemical equations are based on the mass ratio between reactants and products. Therefore, the mass of the reactant is known to calculate the mass of the product; The mass of the reactant can be calculated knowing the mass of the product; The mass of one reactant participating in the reaction is known, and the mass of another reactant participating in the reaction can be calculated; The mass of one type of product is known to calculate the mass of another.

Chemical calculation problems reflect the law of matter and its change from the aspect of "quantity". Chemical calculation includes two factors, chemistry and mathematics, in which chemical knowledge is the basis of mathematical calculation, and mathematics is a tool for chemical calculation. According to the calculation of chemical equations, it is necessary to have a clear understanding of the relevant chemical knowledge and be proficient in the chemical equations related to reactions.

If the chemical formula in the chemical equation is written incorrectly, or if there is no trim, the chemical calculation will inevitably lead to an incorrect result.

1. The symbols used in the two are different.

1. Chemical equations.

The chemical equation is based on the chemical formula of a substance with "+"."="to represent.

2. Symbolic expressions.

The symbolic expression is the chemical formula of the substance with "+"."→"to represent.

Second, the difference between the two in trimming.

1. Chemical equations.

Chemical equations need to be balanced on the basis of expressions and need to obey the law of conservation of mass.

2. Symbolic expressions.

No trim is required.

3. The difference between the two in terms of specific meanings.

1. Chemical equations.

The chemical equation not only indicates the reactants, products, and reaction conditions. At the same time, the stoichiometric number represents the quantitative relationship between the reactants and the product substances, and the mass relationship between the substances can also be expressed through the relative molecular mass or relative atomic mass, that is, the mass ratio between the substances. For gas reactants and products, the volume ratio can also be obtained directly from the stoichiometric number.

2. Symbolic expressions.

It is a rough representation of a chemical reaction before learning the law of conservation of mass, and it is just an excessive state.

1. The requirements are different.

The former needs to be balanced according to the actual situation, which can reflect an objective fact;

The latter does not need to be balanced on the basis of expressions, it is just a form.

2. The details are different.

The former is connected by an equal sign, and the gas symbol or precipitation symbol should be marked on the right side of the product;

The latter is connected by writing arrows, and there is no need to label the product with a gas symbol or a precipitation symbol.

3. The conditions are different.

The former, as a formal relational state, needs to obey the law of conservation of mass in order to represent chemical reactions;

The latter is used as a rough transition state to represent chemical reactions before the law of conservation of mass is learned.

Symbolic expressions only qualitatively represent the changes in the substances in the chemical reaction, while chemical equations not only qualitatively represent the changes in the substances in the reaction, but also quantitatively represent the changes in the quantities of the reactants in each of them, such as the quantities of substances and the quantities of formulas.

The symbolic expression h2+o2---h2o simply indicates that hydrogen and oxygen react in the reaction to produce water.

The equation 2H2+O2=2H2O does not simply mean that hydrogen and oxygen react in the reaction to produce water.

And it also shows that 2 molecules of hydrogen and a molecule of oxygen produce 2 molecules of water, and there are other quantities of the relationship, etc.

The symbolic expression is not balanced, just write the reactants and the product, and the middle does not need to be used, but the reaction conditions are all to be written, and the coefficients are all 1, and there is no need to balance.

The chemical equation is to be balanced.

I remember when I was in junior high school, I learned expressions, and in high school, I used equations.

All back... China's test-oriented education is centered on memorization. If you haven't been out of high school yet.

Back is a way out. Of course. It's best if you think you can understand.

But. Can you understand so many principles in the third year of junior high school? Chemistry is a subject that you can't just read a textbook.

When you think you understand everything. A new situation will arise again. So.

Back.. Education in China is a shortcut.

Symbolic expressions are not trimmed.

The chemical equation is balanced.

A chemical formula is a formula, there are products and reactants, the chemical symbol is just a symbol, and the chemical symbol is part of the partial chemical formula.

A chemical symbol is a representation of a pure substance.

The chemical formula refers to the reaction relationship between different pure substances.

Bachelor and chemical symbols represent completely different meanings, so this should be a distinction that needs to be paid attention to them, this should be based on the chemical formula, he is a chemical formula, the chemical symbol, it is based on her symbol of a chemical element.

College students and chemical symbols are definitely different, this should be a different meaning of their representatives, so this should be you can practice directly, this should be okay.

The chemical symbolic expressions are: gas HE, neon NE, argon AR, krypton KR, xenon XE, radon RN, gold AU, silver AG, copper Cu, iron Fe, aluminum AL, calcium CA, sodium Na, potassium K, carbon C, phosphorus P, sulfur S, silicon Si, boron B, arsenic AS, hydrogen H2, oxygen O2, nitrogen N2, fluorine F2, chlorine Cl2, bromine water BR2, iodine I2, carbon monoxide CO, carbon dioxide CO2, sulfur dioxide SO2, sulfur trioxide SO3.

In chemistry, it is used to represent the symbols of various elements, all material compositions except mixtures, and their atomic numbers, and can be applied in various reaction formulas. Chemical symbols have undergone different evolutions in different regions, and finally in 1841, chemical symbols with universal use were formed, and they are still used today.

1. How to write element symbolsThe principle of one large and two small: iron (Fe), copper (Cu), magnesium (mg), hydrogen (H), etc.

Second, the ion symbol writing.

Ion symbol: The symbol that indicates the number of positive and negative charges of the ion in the upper right corner of the element symbol. For example, a sodium atom that loses one electron and becomes a sodium ion with a unit positive charge is denoted by "Na+".

The sulfur atom acquires two electrons and bears an element symbol: the first letter of the Latin name of the element is uniformly adopted to represent the element's symbol (the positive and negative numbers are often written in front of the plus and minus signs).

The symbolic expression is different from the Zheng Xue equation, which represents a chemical reaction, and the chemical equation not only represents the destruction of the reaction, but also follows the law of conservation of mass.

That is, the number of atoms and the type of atoms on the left and right sides are equal.

The chemical equation not only indicates the reactants, products, and reaction conditions. At the same time, the stoichiometric number represents the amount of each reactant and product substance.

relationship, by relative molecular mass.

Or relative atomic mass can also express the mass relationship between the substances, that is, the mass ratio between the substances. For gas reactants and products, the volume ratio can be obtained directly from the stoichiometric number.

Summary. Symbolic expressions don't need to be balanced, chemical equations need to be balanced, but strictly speaking, it's not a mistake to write such a kiss.

Kiss, these two are different concepts.

Chemistry in the third year of junior high school is expressed in symbols, and it is written as a chemical equation to give points.

The symbolic expression of chemistry is the chemical formula of the compound, such as H2O, Cl2, and so on.

The child said the same.

Kiss, this can't be shared, it's wrong.

It is said that if a chemical equation is expressed, it cannot be expressed in symbols.

It's not the same, the chemical equation expresses which substances react to produce which substances.

Please take a look at this.

Is that right. Kiss, the child wrote correctly.

Symbolic expressions don't need to be balanced, chemical equations need to be balanced, but strictly speaking, it's not a mistake to write such a kiss.

As follows:

1. Fe(OH)3 iron hydroxide, reddish-brown precipitate.

Soluble alkali reacts with iron salt solutions, such as sodium hydroxide and iron sulfate to form iron hydroxide and sodium sulfate

6NaOH+Fe2(SO4)3==2Fe(OH)3 +3Na2SO42, Cu(OH)2 copper hydroxide, blue precipitate.

Common chemical equations.

CuSO4+2NaOH==Na2SO4+Cu(OH)2 CuCl2+2CaOH==Cu(OH)2 +2CaCl3, CaCO3 calcium carbonate, white precipitate.

Common chemical equations.

Ca(OH)2+CO2==CaCO3 +H2O4, BaCO3 barium carbonate, white precipitate.

Common chemical equations.

na2co3+bacl2==2nacl+baco3↓<>

5. AGCL silver chloride is hypothetical and white precipitate.

6. Baso4 barium sulfate, white precipitate.

These two precipitates are neither soluble in water nor soluble in acid!

Chemical equations that are commonly sold in manuscripts.

Ag2SO4 + BACL2==2AGCL +BASO4 7, mg(OH)2 magnesium hydroxide, white precipitate.

Common chemical equations.

MgCl2+Ca(OH)2==CaCl2+Mg(OH)2 8, Ag2CO3 silver carbonate, white precipitate.

Common chemical equations.

AG2CO3+2HNO3=2AGno3+H2O+CO2 The above content reference: Encyclopedia - chemical formula.