Unit 9 Notes
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Transcript of Unit 9 Notes
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)
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
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
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
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
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