The Chemical Reaction

Hydrogen chloride vapor in the beaker and ammonia in a test tube reacts to form ammonium chloride cloud
The chemical reaction is a natural process that always results in a change kimia.Senyawa compounds or compounds involved early in the reaction is referred to as reactants. Chemical reactions are usually characterized by a chemical change, and will result in one or more products which typically have characteristics different from the reactants. Classically, chemical reactions involve changes involving the movement of electrons in the formation and breaking of chemical bonds, although the general concept is basically a chemical reaction can also be applied to the transformation of elementary particles such as in nuclear reactions.
Reactions with different chemical used in chemical synthesis to produce the desired compounds. In biochemistry, series of chemical reactions that are catalyzed by enzymes form metabolic trajectory, in which the synthesis and decomposition is usually not possible in the cell do.

Grouping of Chemical Reactions
The diversity of chemical reactions and approaches undertaken in the study resulted in the number of ways to classify these reactions, which often overlap. Below are examples of classification of chemical reactions that are usually used.
• isomerization, in which chemical compounds undergo structural rearrangement without any change in its atomic kompoasisi
• The combination of direct or synthesis, in which two or more elements or compounds unite to form a complex product:
N2 + 3 H2 → 2 NH3
• chemical decomposition or analysis, in which a compound is broken down into smaller compounds that:
2 H2O → 2 H2 + O2
• Replacement of single or substitution, characterized by an element is replaced by a more reactive element:
2 Na (s) + 2 HCl (aq) → 2 NaCl (aq) + H2 (g)
• metathesis or double replacement reaction, two compounds which change each other ions or bonds to form different compounds:
NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (s)
• acid-base reactions, broadly speaking, is a reaction between the acid with a base. It has various definitions depending on the acid-base concept is used. Some of the most common definitions are:
 Definition of Arrhenius: acid dissociates in water releasing H3O + ions; bases dissociate in water releasing OH-ions.

The Brønsted-Lowry definition: Acids are proton donors (H +) donors; base is the recipient (acceptor) protons. Surrounding the Arrhenius definition.
 Lewis definition: Acids are electron pair acceptors; bases are electron pair donors. This definition encompasses Brønsted-Lowry definition.
 

Redox reactions, in which there is a change in oxidation number of atoms of compounds that react. This reaction can be interpreted as electron transfer. Examples of redox reactions are:
2 S2O32-(aq) + I2 (aq) → S4O62-(aq) + 2 I-(aq)
Which one is reduced to I-I2 and S2O32-(thiosulfate anion) is oxidized to S4O62-.
• Burning, is a kind of redox reaction in which the materials can be burned to join the elements of an oxidant, usually oxygen, to generate heat and form oxidized products. The term combustion is usually used to refer only to the oxidation of a large scale in the whole molecule. Controlled oxidation at only one single functional group is not included in the combustion process.
C10H8 + 12 O2 → 10 CO2 + 4 H2O
CH2S + 6 F2 → CF4 + 2 HF + SF6
• disproportionation, with one reactant to form two types of products that differ only in oxidation state.
2 + → Sn Sn2 + + Sn4
• Organic Reactions, covering various types of reactions involving compounds which have carbon as its main element.

Chemical Kinetics

Reaction rate of a chemical reaction is a measurement of how the concentration or pressure of the substances involved in reactions change over time. Analysis of the reaction rate is very important and has many uses, for example in chemical engineering and chemical equilibrium studies. The rate of reaction is fundamentally dependent on:
• The concentration of reactants, which usually make the reaction go faster if the concentration is increased. This is caused due to an increase pertumbukan atoms per unit time,
• The surface area available for the reactants to interact with each other, especially the solid reactant in a heterogeneous system. Large surface area will increase the reaction rate.
• Pressure, with increasing pressure, we lowered the volume between molecules so that it will increase the frequency of molecular collisions.
• The activation energy, which is defined as the amount of energy needed to create a reaction that everything starts and goes spontaneously. Higher activation energy implies that the reactants need more energy to start the reaction than the reaction activation energy is lower.
• The temperature, which increases the reaction rate when raised, this is because high temperatures increase the energy of the molecule, thereby increasing inter-molecular collisions per unit time.
• The presence or absence of catalysts. Catalysts are substances that change the trajectory (mechanism) of a reaction and will increase the reaction rate by lowering the activation energy necessary for the reaction can be run. Catalysts are not consumed or changed during the reaction, so that it can be reused.
• For some reactions, the existence of electromagnetic radiation, especially ultraviolet, is needed to decide the bond required for the reaction can be everything starts. This mainly occurs in reactions involving radicals.
The rate of reaction is related to the concentration of substances involved in the reaction. This relationship is determined by the rate equation for each reaction. It should be noted that some reactions have a pace that does not depend on the concentration of the reaction. This is referred to as zero-order reaction.