Unit 9 Notes

Acids, Bases, and Salts

Acids

An acid is a substance that produces Hydrogen ion H+ or hydronium H3O+ in solution

Properties of Acids

1. taste sour2. electrolytes – conduct

electricity because of ions3. corrosive – eat away at

metals as metallic compounds and hydrogen gas is produced

Different Acids

Acid FormulaWhere Found

Hydrochloric(strong)

HCl Stomach, cleaning supplies, “muriatic acid”

Sulfuric(strong)

H2SO4Car batteries, fertilizer

Nitric (strong) HNO3Explosives, fertilizers

Phosphoric H3PO4Detergents, fertilizers

Carbonic H2CO3Soda (carbonated)

Ascorbic H2C2H6O6Vitamin C (fruits and vergetables

Acetylsalicylic HOOC-C6H4-OOCCH3 aspirin

Acetic (weak) CH3COOH vinegar

The most widely used chemical in the world is sulfuric acid. It can cause severe burns because it is a dehydrating agent. This means that it takes all of the water out of materials, including skin.

STRONG ACIDS

A Strong Acid completely ionizes (breaks apart) in water and releases a lot of H+.

Example: sulfuric acid (battery acid)

Weak Acids

A Weak acid only partially beaks down in water, so it doesn’t release much H+.

Example: acetic acid (vinegar)

BasesA BASE is a substance that

produces hydroxide ions OH- in solution. AKA=Alkine

Properties of Bases

1. feel slippery2. taste bitter3. electrolytes4. corrosive

Most bases contain a metal and OH- (hydroxide)

The exception is ammonia, NH3, but it still produces OH- when mixed with water

NH3 + H2O NH4+ + OH-

BASE Formula Where Found

Sodium hydroxide (strong)

NaOH Soap, drain cleaner

Aluminum hydroxide (weak)

Al(OH)2 Deodorant, antacid

Magnesium hydroxide (strong)

Mg(OH)2 Laxative, antacid

Calcium hydroxide (strong)

Ca(OH)2 Mortar, plaster, lime

ammonia (weak)

NH3Cleaners, fertilzer, rayon, nylon

Strong Bases

A strong base completely dissociates (breaks apart) in solution and releases lots of OH-.

Example: sodium hydroxide

Weak Base

A weak base does not completely break apart in solution and does not release as much OH-

Example: Aluminum hydroxide

pH ScalepH is the measure of H3O+ in a

solutionpH is used to measure the strength

of acids and bases. It ranges from 0 to 14.

Substances with a pH lower than 7 are acidic

Substances with a pH higher than 7 are basic

Substances with a pH of 7 are neutral

Indicators

Substances that change color in the presence of acids and bases

Examples: 1. bromythymol blue turns yellow for

acid and blue for base 2. phenylthalein turns clear for acid

and pink for base

pH Scale

Strong Acids

Neutral(pure water)

Strong Bases

Weak Acids

Weak Bases

Neutralization

If you want to NEUTRALIZE an acid or base, you add a BUFFER.

BuffersBuffers are ACIDS, BASES, or

SALTS that are mixed with acids or bases to make their pH closer to 7.

If you want to neutralize an acid, your buffer must be a BASE

If you want to neutralize a base, your buffer must be an ACID

Buffers in your body help keep your blood’s pH at 7.4. This is necessary because most of your food contains ACIDS

Titration

Process that can be used to determine the concentration of an acid or base

Neutralization is a chemical reaction between an acid and a base

H+ from the acid combine with OH- from the base to form water

Metals from the base combine with nonmetals from the acid to form a salt

Example:

HCl + NaOH NaCL + H2O

Salts

Most SALTS are formed with a METAL and a NONMETAL other than OXYGEN.

Some salts are formed with a METAL and a POLYATOMIC ION.

Salt Formula Uses

Sodium chloride

NaCl Food preparation

Sodium bicarbonate

NaHCO3 Baking soda

Calcium carbonate

CaCO3 Chalk

Ammonium chloride

NH4Cl Batteries

Sodium phosphate

Na2PO4 Detergents

Acid Rain

Unpolluted rain typically has a pH value of 5.6 which is acidic, but not harmful

Any rain that is below 5.6 is considered acid rain

Acid Rain Can:1. Dissolve marble in buildings and statues2. Corrode metal (buildings, cars)3. Kill plankton (then fish die)

Ways Acid Rain can Occur

Burning coal releases sulfur – sulfur combines with water in the air – sulfuric acid forms

Car exhaust releases nitrogen oxide – combines with water – nitric acid forms

Ways to Prevent Acid Rain

“scrubbers on smokestacks”Nuclear powerCleaner fuel

Soaps

Soaps are organic salts, this means that they contain carbon.

Soaps are made by reacting fats or oils with sodium hydroxide or potassium hydroxide.

Soaps made with NaOH are solidsSoaps made with KOH are liquidsGlycerin is another product of this

reaction which is used in lotion

The process of making soap is called SAPONIFICATION

Detergents

Detergents are similar to soaps, but fo not form soap scum which is a precipitate that forms when soap is used in hard water (lots of minerals)

This is why most laundry products are detergents, not soaps

Esters

An ESTER is an organic compound formed by the reaction of an organic acid with an alcohol

Esters are responsible for the odors and flavors of flowers, fruits, and other foods. Esters are added to jello and candy to give the flavors of strawberry, banana, or apple.

Organic acids are also used to make polyester fibers