Minggu, 14 Oktober 2012

CHEMICAL


This is one of my chemistry lesson class time XI, was sich a little difficult but fun especially teachers are very good. :)

Acid-Base

Acids and Bases are two classes of chemicals that are important in everyday life. In connection with the acid tongue, solutions are grouped into three categories, namely acidic, alkaline, and neutral. Acids and bases have different properties, so can we can determine the nature of a solution. To determine a solution is acidic or alkaline, there are a number of ways. The former uses a color indicator, which would indicate the nature of a solution with the color changes. Litmus example, is red in an acidic solution and is blue in alkaline solution. Acid-base properties of a solution can also be determined by measuring the pH. pHmerupakan a parameter used to express the acidity of the solution. Acid solution has a pH less than 7, alkaline solution having a pH greater than 7, while neutral solution has a pH = 7. pH of a solution can be determined with a pH indicator or a pH meter.



Acid-Base Theory Arrhenius

Since centuries ago, chemists define acids and bases based on the nature of the solution. Acid solution has a sour taste and corrosive (damage metal, marble, and various other materials). whereas alkaline taste is somewhat bitter and caustic (slippery).
But there are some opinions that explain the cause of the nature of acids and bases. In 1777, Antoine Laurent Lavoisier (1743-1794) suggested that the acidic oxygen-containing elements. Davy then concluded that the elements which constitute the basic elements hidrogenlah acid. Then in 1814 Joseph Louis Gay-Lussac (1778-1850) concluded that an acid is a substance that can neutralize the alkali and the two classes of compounds that can only be defined in relation to one another.
But the concept / idea is quite satisfactory, and acceptable to date advanced by Svante August Arrhenius (1859-1927), namely:
• acid
acid is a substance in water releasing H + ions. in other words, the nature of the acid is H + ions. and formulated with
Hxz (aq) --------- »xH + (aq) + Zx-(aq)

• base
base is a substance in water produces hydroxide ions (OH-). in other words, the nature of bases is (OH-). and formulated with

M (OH) x (aq) --------- »Mx + (aq) + XOH-(aq)

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