cause and effect chemical reaction

CHEMICAL REACTIONS

Chemical reactions are said to or take place if one of the following things should be observed: they produce 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.

The characteristics of a chemical reaction are:

1.        Color Changes occurred

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 exothermic reaction, there is transfer of heat energy from sisitem to the environment. At the endothermic 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 the presence of the formed gas is indicated by 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 replacement used chemical formulas. The result is called the skeleton equation. Example: No + O ₂ → No ₂

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

Types of chemical reactions:

A.Burning.

Burning 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) + 14H 2O (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) → CH3 OH (9)

C.Indonating

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 transfers another element in a compound. Cu (p) + 2Ag + (ag) CU2 + (ag) + 2 Ag (p)

E.Metatesis (transfer date)

Is a reaction where there is an exchange between two reactions.

AgNo 3 (ag) → NaCL (ag) → AgCL (p) + NaNO3 (ag)

The best way to give 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 comparative order and comparative law resides. The fundamental fundamentals underlying all the changes of chemistry are the theoretical chemistry areas, the correlation between the concept of elements and the compounds with the four laws mentioned above is obtained in Dalton Theory of Dalton, the first modern theory of atoms and molecules as fundamental particles of matter The ingenuity that grows out of this theory is, among other things, the scale, the relative atomic weight of the elements dissolved according to the increase of atomic weight, the appearance of the elements regularly with certain properties encourages the meddeleu to arrange periodic tables of the elements and predict the existence of some elements not yet known.

Factors Affecting Reaction Speed Some factors that affect the rate of reaction include the concentration, the nature of the reacting agent, the temperature and the catalyst.

A.      CONCENTRATION

From various experiments show that the greater the concentration of substances that react the faster the reaction takes place. The greater the concentration of the more substances that react so that the greater the likelihood of occurrence of collisions thus the greater the likelihood of reaction.

B.       PROPERTIES OF THAT REACTED

The easy nature of a substance to react will determine the rate at which the reaction proceeds.

It is generally stated that:

-	The reaction between ionic compounds is generally rapid. This is due to the attraction of the ions with the opposite charge. Example: Ca 2+ (aq) + CO 3 2+ (aq) ® CaCO 3 (s) This reaction takes place quickly.
-	The reaction between covalent compounds is generally slow. This is because the reaction takes energy to break the covalent bonds in the molecule of the reacting agent. Example: CH 4 (g) + Cl 2 (g) ® CH 3 Cl (g) + HCl (g) This reaction runs slow reaction can be accelerated if given energy such as sunlight.

C.      TEMPERATURE

In general, the reaction will take place more quickly when the temperature is raised. By raising the temperature the kinetic energy of the reacting substances molecules will increase so that more molecules will have energy equal to or greater than Ea. Thus more molecules can reach the transition state or in other words the reaction rate becomes larger. Mathematically the relationship between the value of the reaction rate constant (k) to temperature is expressed by the ARRHENIUS formulation:

K = A .e E / RT

Where:
K: reaction rate constant
A: Arrhenius's fixed-price constant for each reaction
E: energizing energy
R: universal gas constant = 0.0821.atm / mol ^o K = 8,314 joules / mol ^o K
T: reaction temperature ( ^o K)

D.      CATALYST

The catalyst is a substance added to a reaction in order to increase the reaction rate. The catalyst is sometimes involved in the reaction but does not undergo permanent chemical changes, in other words at the end of the catalyst reaction to be recovered in the same form and amount as before the reaction.

The function of the catalyst is to increase its reaction speed (accelerate the reaction) by minimizing the activation energy of a reaction and the formation of new reaction steps. With decreasing energizing energy, at the same temperature the reaction can take place more quickly

Four basic reactions

1.        Synthesis

In direct combination or synthesis reactions , two or more simple compounds combine to form new, more complex compounds. Two reactants or more that react produce one product is also one way to know if it's a synthesis reaction. An example of this reaction is that hydrogen gas combines with oxygen gas which results in water. ^[15]

Another example is that nitrogen gas joined with hydrogen gas will form ammonia, with the equation of the reaction:

N ₂ + 3 H ₂ → 2 NH ₃

2.   Decomposition

The decomposition or analysis reaction is the opposite of the synthesis reaction. A more complex compound will be broken down into simpler compounds. ^{[15] [16]} Examples are water molecules that are broken down into oxygen gas and hydrogen gas, with the equation of the reaction:

2 H ₂ O → 2 H ₂ + O ₂

3.        Single replacement

In a single replacement or substitution reaction , a single element replaces the other single element in a compound. An example is a sodium metal which reacts with hydrochloric acid to produce sodium chloride or a salt of the kitchen, with the reaction equation:

2 Na (s) + 2 HCl (aq) → 2 NaCl (aq) + H ₂ (g)

4.        Double replacement

In a double-replacement reaction, two compounds exchange ions or bonds to form different new compounds. ^[15] This occurs when the cations and anions of two different compounds move locally, forming 2 new compounds. ^[16] The general formula of this reaction is:

AB + CD → AD + CB

An example of a double-replacement reaction is lead (II) nitrate reacting with potassium iodide to form lead (II) iodide and potassium nitrate, with the reaction equation:

Pb (NO ₃ ) ₂ + 2 KI → PbI ₂ + 2 KNO ₃

Another example is sodium chloride (salt kitchen) reacts with silver nitrate to form sodium nitrate and silver chloride, with the equation of the reaction:

NaCl (aq) + AgNO ₃ (aq) → NaNO ₃ (aq) + AgCl (s)

Reference :
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