Meeting to 11 :Cause and effect when a chemical reaction occurs

Cause and effect when a chemical reaction occurs  ( Sebab dan akibat bila terjadi suatu reaksi kimia )

Chemical reactions

Chemical Reactions That Cause Color Change

     Whenever a chemical reaction occurs, the changes that people observe are caused by the creation or loss of certain types of materials. For instance, temperature can generate a chemical reaction. An easy way to recognize a chemical change is to compare the color of the original item with the new one. A number of chemical reactions cause color changes

    Chemical reactions are said to or take place if one of the following things should be observed ie the reaction produces gas, sediment, temperature change and color change. Chemical reactions are a process whereby new substances, the reaction product, are formed from some of the original substances, called reactants. Usually a chemical reaction is accompanied by physical events, such as discoloration, sediment formation, or gas generation. Symbols expressing a chemical reaction are called chemical equations.

water reaction

The characteristics of a chemical reaction are:

1. Color Changes occur

     In chemical reactions, the reactants are converted into products. Changes that occur can be caused by the breaking of bonds antaratom reactants and the formation of bonds that bru make the product. To break the bond needed energy. To form a new bond, it releases some energy. Thus, in chemical reactions there is a change of energy. The chemical reaction that produces energy in the form of heat is called an exothermic reaction. The reaction that absorbs heat energy is called the endothermic reaction.

   Example: Fire can warm a cold body and when breathing heat exists in the body due to exercise is released so the body becomes cold.

2. Temperature Changes occur

    In chemical reactions, the reactants are converted into products. Changes that occur can be caused by the breaking of bonds reagent antaratom and the formation of new bonds that make up the product. To break the bond needed energy.Chemical reactions that produce energy in the form of heat are called exothermic reactions, while reactions that absorb heat energy are called endothermic reactions. Chemical reactions occur in a space we call dbngan system, where outside the system called the environment. In the exothermic reaction, there is transfer of heat energy from sisitem to the environment. At the endothermal reaction is the transfer of heat energy from the environment to the system.

3. Occurs Sediment Formation

When reacting two solutions in a test tube, it sometimes forms an insoluble, solid compound, separated from the solution. The solids are called sediments (precipitates)

4. Gas Formation occurs

Simply put, in the chemical reaction of the formed gas is indicated in the presence of bubbles in the reacted solution. The presence of gas can be known from its peculiar smell, such as sulfidic acid (H2S) and ammonia (NH3) that smells rotten.In writing the equation of the reaction required three steps:

A. The names of reactants and reaction products are written, the result is called a equation called.Example: nitrogen oxide + oxygen → Nitrogen dioxide

B. As a substance name penggantin used chemical formulas.The result is called the frame equation.Example: No + O2 → No2

C. The skeletal equations are then in equilibrium, which results in a chemical equation. Example: 2No + O2 → 2No2

Types of chemical reactions:

A.Burning.

Combustion is a reaction in which an element or compound with oxygen forms a simple oxygen-containing compound.

Example :

CO2, H2O and SO2

C3H8 (9) + 5O2 (9) → 3CO2 (9) + 4H2O (9)

2C6H14O4 (9) + 15O2 → 12Co2 (9) + 14H2O (9)

B.Collection (synthetic)

A reaction in which a more complex substance is formed from two or more simpler substances (both elements and compounds).

2H2 (9) + O2 → 2H2O (9)

CO (9) + 2H2 (9) → CH3OH (9)

C.Indoning

Is a reaction in which a substance is broken down into simpler substances 2Ag2O (p) → 4Ag (p) + O2 (9)

D.Changes (Shift date)

Is a reaction in which an element is transferred to another element in a compound. Cu (p) + 2Ag + (ag) CU2 + (ag) + 2 Ag (p)

E.Metatesis (transfer date)

Is a reaction where there is exchange between two reactions.

AgNo3 (ag) → NaCL (ag) → AgCL (p) + NaNO3 (ag)

    The best way to provide a chemical reaction is to write a balanced chemical equation which is a qualitative and quantitative statement of the reactants involved. Each substance is represented by its molecular formula. Express the number of atoms of all kinds in a unit of that substance. The molecular formula is a multiplier of the empirical formula of the substance that states

    The minimum amount possible in the correct comparison of atoms of each kind. The three general classes of reactions encountered with melaus in chemistry are direct combination reactions, simple change reactions and double preconditioning reactions. Quantitative relationships between reactants and reaction products in a balanced chemical equation provide a stripometric basis.The calculation of staikiomentry requires the use of elemental weight of the element and the weight of the compound molecule. The amount of a particular reaction which is calculated will be obtained in a theoretical rendement chemical reaction for a chemical reaction. It is important to know which are limiting reagents ie reagents that can theoretically react to exhaustion, whereas other reagents are excessive.

If chemical reactions occur, three kinds of changes can be observed: a. Changes in Nature

B.Change Changes

C. Energy Changes

    All chemical changes are certainly parent on the law of preservation of energy laws and the law of mass energy preservation. A certain composition of senyawakimia by the law of definite order and comparative law resides. The fundamental fundamentals underlying all the kimiam changes are the theoretical chemistry areas, the correlation between the concept of elements and the compound with the four laws mentioned above is obtained in Dalton Theory of Dalton, modern theory First about the atoms and molecules as fundamental particles of substances grown from this theory include the scale, the relative atomic weight of the elements dissolved according to the increase of atomic weights, the appearance of the elements regularly with certain properties pushed the meddeleu arrange the periodical table Of the elements and predicted the existence of some unknown elements.