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Shvoong Home>Science>Chemistry>http://chemistry.about.com Summary

http://chemistry.about.com

Website Summary   by:kimiyasi    
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  • There are so many methods to defining acids and bases. Example Antoine Lavoisier, Humphry Davy, and Justus Liebig. but they did not definitions acid and base in theory. And then :1. Svante Arrhenius, give definition of acid and base : a. acids is produce H+ ions in aqueous solutions ( water ), b.bases is produce OH- ions in aqueous solutions (water ). 2. Johannes Nicolaus Brønsted - Thomas Martin Lowry : a. acids are proton donors, b. bases are proton acceptors. and 3. Gilbert Newton Lewis : a. acids are electron pair acceptors, b. bases are electron pair donors
  • Properties of Acids :1. taste sour (don't taste them!)... the word 'acid' comes from the Latin acere, which means 'sour', 2. acids change litmus (a blue vegetable dye) from blue to red, 3. their aqueous (water) solutions conduct electric current (are electrolytes), 4. react with bases to form salts and water, revolve hydrogen gas (H2) upon reaction with an active metal (such as alkali metals, alkaline earth metals, zinc, aluminum). and the Properties of Bases : a. taste bitter (don't taste them!), b. feel slippery or soapy (don't arbitrarily touch them!), c. bases don't change the color of litmus; they can turn red (acidified) litmus back to blue, d. their aqueous (water) solutions conduct and electric current (are electrolytes), e. react with acids to form salts and water
  • this is the examples Acids : a. citric acid (from certain fruits and veggies, notably citrus fruits), b. ascorbic acid (vitamin C, as from certain fruits), c. vinegar (5% acetic acid), d. carbonic acid (for carbonation of soft drinks), e.lactic acid (in buttermilk). the examples Bases : a. detergents, b. soap, c. lye (NaOH), d. household ammonia (aqueous)

    how naming and the formulas of some acids and bases? we can devide acid with Binary Acids and ternary acids. A binary compound consists of two elements.Binary acids have the prefix hydro in front of the full name of the nonmetallic element. They have the ending -ic. Examples include hydrochloric and hydrofluoric acid.

    Examples :a. Hydrofluoric Acid – HF, b. Hydrochloric Acid – HCl, c. Hydrobromic Acid – HBr, d. Hydroiodic Acid – HI,e. Hydrosulfuric Acid - H2S. Ternary Acids commonly contain hydrogen, a nonmetal, and oxygen. The name of the most common form of the acid consists of the nonmetal root name with the -ic ending, The acid containing one less oxygen atom than the most common form is designated by the -ous ending. An acid containing one less oxygen atom than the -ous acid has the prefix hypo- and the -ous ending. The acid containing one more oxygen than the most common acid has the per- prefix and the -ic ending.

    Examples :a. Nitric Acid - HNO3, b. Nitrous Acid - HNO2, c. Hypochlorous Acid – HclO d. Chlorous Acid - HClO2 e. Chloric Acid - HClO3

    we can see the different between Strong Acid or Strong Base by see the dissociate in water. Strong electrolytes are completely dissociated into ions in water. The acid or base molecule does not exist in aqueous solution, only ions. Weak electrolytes are incompletely dissociated. Strong Acids completely dissociate in water, forming H+ and an anion. There are six strong acids. The others are considered to be weak acids. You should commit the strong acids to memory:

    a. HCl - hydrochloric acid b. HNO3 - nitric acid c. H2SO4 - sulfuric acid d. HBr - hydrobromic acid e. HI - hydroiodic acid

    f. HClO4 - perchloric acid

    100% dissociation isn't true as solutions become more concentrated. If the acid is 100% dissociated in solutions of 1.0 M or less, it is called strong. Sulfuric acid is considered strong only in its first dissociation step.

    H2SO4 -> H+ + HSO4-

    Weak Acids only partially dissociates in water to give H+ and the anion. Examples of weak acids include hydrofluoric acid, HF, and acetic acid, CH3COOH. Weak acids include: Molecules that contain an ionizable proton. A molecule wih a formula starting with H usually is an acid. Organic acids containing one or more carboxyl group, -COOH. The H is ionizable. Anions with an ionizable proton. (e.g., HSO4- --> H+ + SO42-), Cations ( transition metal cations, heavy metal cations with high charge, NH4+ dissociates into NH3 + H+) Strong Bases dissociate 100% into the cation and OH- (hydroxide ion). The hydroxides of the Group I and Group II metals usually are considered to be strong bases.LiOH - lithium hydroxide,NaOH - sodium hydroxide, KOH - potassium hydroxide, RbOH - rubidium hydroxide, CsOH - cesium hydroxide, *Ca(OH)2 - calcium hydroxide, *Sr(OH)2 - strontium hydroxide, *Ba(OH)2 - barium hydroxide

  • * These bases completely dissociate in solutions of 0.01 M or less. The other bases make solutions of 1.0 M and are 100% dissociated at that concentration. There are other strong bases than those listed, but they are not often encountered. Examples of weak bases include ammonia, NH3, and diethylamine, (CH3CH2)2NH. Most weak bases are anions of weak acids. Weak bases do not furnish OH- ions by dissociation. Instead, they react with water to generate OH- ions.

    Published: January 13, 2012   
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