ACIDS AND BASES

CLENT MARK C. GAITERAJOHN ALEX C. OCAY

1. What are the physical and chemical behavior of acids and

bases? Acids • Taste sour, are corrosive to metals, change

litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.

Bases • Feel slippery, change litmus blue, and

become less basic when mixed with acids.

Arrhenius suggested that acids –Are compounds that contain hydrogen–Can dissolve in water to release

hydrogen ions into solution. –Neutralize bases in a neutralization

reaction. –Corrode active metals–Acids turn blue litmus to red–Acids taste sour

Arrhenius defined bases-As substances that dissolve in water to release hydroxide ions (OH-) into solution. -Neutralize acids in a neutralization reaction-Denature protein.-Turn red litmus to blue.-Taste bitter.

The Brønsted-Lowry definition of acids–Any substance that can donate a

hydrogen –Often referred to as proton donors

because an H+ ion, hydrogen minus its electron, is simply a proton

The Brønsted definition of bases –Any substance that can accept a

hydrogen ion.  –The opposite of an acid.

• The Lewis definitions of acids

–Are electron pair acceptors

• The Lewis definitions of bases

–Are electron pair donors.

• We can differentiate acid from a base by:

-Tasting (sour – acid, bitter – base)

-Using pH indicators (litmus paper, methyl red etc.)

2. How do we differentiate an acid from a base?

• You can identify the strengths by testing them using pH indicators 

• Strong Acid: An acid that has a very low pH (0-4).

• Strong Base: A base that has a very high pH (10-14).

• Weak Acid: An acid that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (3-6).

3. How are the strength of acids and bases identified?

• Weak Base: A base that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (8-10).

• Neutral: A solution that has a pH of 7. It is neither acidic nor basic.

• Acids and Bases are quantified by the use of Ka, for acid dissociation constant while Kb, for base dissociation constant. These constants are expressed as the product of the concentrations of the ions formed after dissociation divided by the original concentration of the substance.

4. How are acids and bases quantified?

• a weak acid or a weak base. • The undissociated form is a different color

than the iogenic form. • does not change color from pure acid to pure

alkaline at specific hydrogen ion concentration, but rather, color change occurs over a range of hydrogen ion concentrations. This range is termed the color change interval. It is expressed as a pH range.

5. What are pH indicators?

• The most important single use of acids and bases is in the manufacture of other chemicals. Fertilizers, synthetic fabrics, pigments, petroleum, iron and steel, explosives, dyes, plastics, pesticides, soaps and detergents, paper, film, and many other chemicals are produced from acids and bases. They are also used for various other purposes, including cleaning surfaces, refining oil and sugar, electroplating metals, and treating food products.

6. What are common applications/uses of acids

and bases?