Reactant The starting substance

Reactant the starting substance of a chemical reaction shown to the left of the reaction arrow. 

Raoult s law. The vapor pressure of the solvent over a solution is given by the product of the vapor pressure of the pure solvent and the mole fraction of the solvent in the solution. (12.6) rare earth series. See lanthanide series, rate constant (it). Constant of proportionality between the reaction rate and the concentrations of reactants. (13.1) rate law. An expression relating the rate of a reaction to the rate constant and the concentrations of the reactants. (13.2) rate-determining step. The slowest step in the sequence of steps leading to the formation of products. (13.5) reactants. The starting substances in a chemical reaction. (3.7) reaction mechanism. The sequence of elementary steps that leads to product formation. (13.5)... 

Explanation of this rule was not possible in Markovnikov s time because the theory of chemical reactions and electronic structure had not yet been developed. To gain deeper insight into the details of the observed behavior it is necessary to introduce a new chemical concept, the reaction mechanisms. The mechanism of chemical reaction describes successive events along the way from reactants (the starting substances) to the products. What is the nature of these successive steps One example of the reaction mechanism was already discussed the reaction of catalytic hydrogenation. 

We will now begin to present chemical reactions in detail. You will learn how to write equations for those reactions. Recall from Section 2.8 that an equation shows the formulas of the reactants-the starting substances that will be destroyed in the chemical change-written on the left side of an arrow, The formulas of the products of the reaction-the new substances formed in the chemical change—are written on the right side of the arrow. 

As one other familiar reference, consider photosynthesis. You have undoubtedly heard many times that this is the chemical process by which a plant stores the energy of the sun. Much is known about the chemical reactions of photosynthesis and it is indeed true that they result in formation of chemical compounds with higher heat content than the starting substances. These reactions will not occur in the absence of light— the light supplies the energy required to raise the reactants to the higher heat content of the products. 

A chemical reaction is a process in which the starting substances are changed into different substances. That is, the products are different from the reactants or the starting substances. The individual properties of the starting materials disappear and the products have their own properties. However, the mass of the products remains equal to the mass of the reactants. 

Reactant a starting substance in a chemical reaction. It appears to the left of the arrow in a chemical equation. (3.6) Reaction mechanism the series of elementary steps involved in a chemical reaction. (15.6)... 

Chemists use statements called equations to represent chemical reactions. Their equations show a reaction s reactants, which are the starting substances, and products, which are the substances formed during the reaction. Chemical equations do not express numerical equalities as do mathematical equations because during chemical reactions the reactants are used up as the products form. Instead, the equations used by chemists show the direction in which the reaction progresses. Therefore, an arrow rather than an equal sign is used to separate the reactants from the products. You read the arrow as react to produce or yield . The reactants are written to the arrow s left, and the products are written to its right. When there are two or more reactants, or two or more products, a plus sign separates each reactant or each product. These elements of equation notation are shown below. 

Reactants and Products. There are many different ways that chemicals combine, or react. A chemical reaction occurs when one substance is broken apart and then put together as a new substance. Reactants are the starting substances. Scientists call the new substances products. Atoms and molecules rearrange during a chemical reaction, but do not disappear or change. Reactions speed up when special chemicals are used. Reactions also release some form of energy. 

In chemical reactions, the starting substances are called reactants, and the new substances that are formed are called products. Terms such as decompose, explode, rust, oxidize, corrode, tarnish, ferment, burn, or rot generally refer to chemical reactions. 

Reactant a starting substance in a chemical reaction. It appears to the left of the arrow in a chemical equation. 

The generalization on reactions where not all conversion numbers are just +1 (for products) or — 1 (for reactants) is not difficult. Because we would like to retain the usual representation of the conversion formula with the starting substances on the left side of the reaction arrow, we choose the following notation ... 

We read the + sign as reacts with and the arrow as produces. TThe chemical formulas to the left of the arrow represent the starting substances, called reactants. TThe chemical formulas to the right of the arrow represent substances produced in the reaction, called products. The numbers in front of the formulas, called coefficients, indicate the relative numbers of molecules of each kind involved in the reaction. (As in algebraic equations, the coefficient 1 is usually not written.)... 

Next, we leam how to write a ehemical equation to describe the outcome of a chemical reaction. A chemical equation must be balanced so that we have the same number and type of atoms for the reactants, the starting materials, and the products, the substances formed at the end of the reaction. (3.7)... 

Reactant a starting substance in a chemical reaction. (2.9) Reaction intermediate a species produced during a reaction that does not appear in the net equation because it reacts in a subsequent step in the mechanism. (14.7)... 

An elementary step represents an actnal Interaction between the reactant molecules In the step. An overall reaction equation shows only the starting substances and the ending substances, not the path between them. 

A chemical change occurs when one or more substances change into new substances. A chemical change is also known as a chemical reaction. The appearance of new substances is the sign that a chemical reaction has occurred. In a chemical reaction, the substances present at the start are called reactants. The new substances that are formed in the reaction are called products. A chemical reaction is represented by a chemical equation, which shows the relationship between reactants and products. 

Statements called equations are used to represent chemical reactions. Equations indicate the reactants, or starting substances, and the products, or substances formed during the reaction. The reactants are written to the left of an arrow that stands for yields, and the products are written to the right. Plus signs are used to separate the different reactants or products. The symbols (s), (1), (g), and (aq) indicate solid, liquid, gas, or water solution (aqueous), respectively. 

Reactants are the substances that enter into a chemical reaction. This term is often applied to all the substances involved in a reversible reaction, but it can also be limited to the substances that appear on the left side of a chemical equation—the starting substances. (Substances on the right side of the equation are usually called products.)... 

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