A chemical equation (see example below) consists of a list of reactants (starting substances) on the left, an arrow symbol and a list of products (substances formed during the chemical reaction) on the right. Each substance is designated by its chemical formula, preceded where appropriate by a number called the stoichiometric coefficient. [a] The coefficient indicates how many entities (e.g. molecules) of this substance are involved in the reaction on a molecular basis. If not written explicitly, the coefficient is equal to 1. Several substances on each side of the equation are separated by a plus sign. The chemical equations are either unbalanced or balanced. Let`s assign the stoichiometric coefficients of the chemical equation in the previous section to the variables and write the corresponding linear equations: So, in this case, I replace the = sign in the chemical equation with the ⇄ sign, which in reality not only expresses equality, but also indicates the direction of the reaction. This clearly expresses that a chemical action occurs simultaneously in two opposite directions. Now, Dr. Pfaundler has combined these two phenomena into a single concept, considering the observed limit as the result of two opposing reactions, one of which, in the example cited, leads to the formation of sea salt [i.e. NaCl] and nitric acid [and] the other to hydrochloric acid and sodium nitrate. This reasoning, which confirms the experiment, justifies the term «chemical equilibrium» used to characterize the final state of bounded reactions.

I would suggest translating this expression by the following symbol: an extension is sometimes used in which certain substances with their stoichiometric coefficients are moved above or below the arrow, which is preceded by a plus or nothing sign for a reagent and a minus sign for a product. Then the same equation may look like this: called a stoichiometric number,[h] which simplifies linear equations to An example of an ionic chemical equation is given below. Chemical equations in which electrolytes are represented as dissociated ions are commonly referred to as ionic equations. They are often used to represent displacement reactions that take place in aqueous media. In these reactions, some ions participate in the reaction and others do not. Ions that do not react are called spectator ions and are usually omitted from the net ion equation. where νj are the stoichiometric coefficients described above. The zj can be incorporated as an additional line in the matrix aij described above[6][7], and a properly balanced ionic equation then also obeys: To indicate the physical state of a chemical, a symbol in parentheses can be added to its formula: (s) for a solid, (l) for a liquid, (g) for a gas and (aq) for an aqueous solution. This happens especially if you want to focus on the conditions or their changes.

For example, the reaction of aqueous hydrochloric acid with solid (metallic) sodium with aqueous sodium chloride and hydrogen gas would be written as follows: The problem with the main theorem we just cited is that each side of the equation is used as a measure of the other. There are acid-base reactions that produce a precipitate in addition to the water molecule shown above. An example is the reaction of barium hydroxide with phosphoric acid, which produces not only water, but also the insoluble salt barium phosphate. In this reaction, there are no spectator ions, so the net ion equation is the same as the complete ionic equation. The use of negative stoichiometric coefficients on both sides of the equation (as in the example below) is not widely used and is often not recommended. [5] [best source needed] A chemical equation is something you will encounter every day in chemistry. It is a written representation of the process that occurs during a chemical reaction, using numbers and symbols. Chemical reactions can be represented on paper using chemical equations, for which an example is given below (for the reaction between hydrogen gas and oxygen gas with water). In ionic chemical equations, electrolytes (substances that dissociate into ions when dissolved in polar solvents) are broken down and written as separate ions.

These equations are very useful for describing single displacement reactions and salt metathesis reactions (commonly referred to as double displacement reactions). The system of linear equations presented in the previous section can also be written using an efficient matrix formalism. To first unify the stoichiometric reagent and the stoichiometric coefficients of the product sj, give the quantity For each chemical element (or nuclide or unchanged unit or charge) i, its conservation requirements can be expressed by the mathematical equation. By comparing the reactants and products of the ionic equation and the chemical equation, it can be observed that the Ca2+ (calcium ion) and NO3– (nitrate) ions are present on both sides of the ionic equation. These ions are called bystander ions because they are not involved in the chemical reaction. Some examples of chemical equations are listed in the bullet points below. Double-displacement reactions, in which a carbonate reacts with an acid, have the net ion equation: it is common to place the reactants on the left side of a chemical equation and the products on the right. The arrow between the reactants and the products should point from left to right or, if the reaction is in both directions, point in both directions (this is common). If your arrow points from right to left, it`s a good idea to rewrite the equation in a conventional way. In this reaction, the Ca2+ and NO3− ions remain in solution and are not part of the reaction.

That is, these ions are identical on the reactive and product sides of the chemical equation. Since these ions do not participate in the reaction, they are called spectators. A net ion equation is the complete ionic equation from which the spectator ions have been removed. [8] The net ionic equation of current reactions is as follows: Chemical equations use symbols to represent factors such as the direction of reaction and the physical states of reactive entities. Chemical equations were first formulated in 1615 by the French chemist Jean Béguin. A chemical equation is written with the reactants on the left side of an arrow and the products of the chemical reaction on the right. The arrow head usually points to the right or to the product side of the equation, although some equations may indicate equilibrium, with the reaction occurring simultaneously in both directions. A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulas, with reactive entities on the left and product entities on the right.

The basic equation of the economist is therefore that the value of everything is proportional to its cost. There is a certain way of writing what is in a molecule called a chemical formula. The chemical formulas for all the elements that make up each molecule and use a small number at the bottom right of an element`s symbol to represent the number of atoms of that element. For example, the chemical formula for water is H2O. All solutions of this linear system of equations have the following form, where is any real number: Since no nuclear reaction takes place in a chemical reaction, the chemical elements undergo the reaction unchanged. Therefore, each side of the chemical equation must represent the same number of atoms of a given element (or nuclide, if different isotopes are taken into account). The same applies to the entire electrical charge, as provided for in the Charges Conservation Act. An equation that meets these requirements is called balanced.

Balancing the chemical equation for complete methane combustion The result is a homogeneous system of linear equations that can be easily solved using mathematical methods. Such a system always has the trivial solution of zeros, which we are not interested in, but if there are additional solutions, there will be an infinite number of them. Any non-trivial solution balances the chemical equation. A «preferred» solution is a solution with integer stoichiometric coefficients, usually positive, sj with the greatest common divisor equal to one. You need to know the symbols of the elements to understand what happens in a chemical reaction. In this reaction, C is carbon, H is hydrogen and O is oxygen. The standard notation for chemical equations allows only all reactants on one side, all products on the other side, and all positive stoichiometric coefficients. For example, the usual form of the dehydration equation is dimethyl ether methanol: if each ion is a «bystander ion», then there has been no reaction, and the net ion equation is zero. This ionic chemical equation can be interpreted as follows: two chloride ions derived from calcium chloride react with two silver cations derived from silver nitrate, forming a precipitate of silver chloride as a product.

As an example, the equation of the reaction of hydrochloric acid with sodium can be called: In the following pages, you will learn more about how to balance an equation in detail. Balancing chemical equations How do you balance chemical equations? Ionic chemical equations give the net electric charge of reactants and products.