Acids & BasesThey are everywhere..

In your foodIn your house

EVEN IN YOU!!!!!

What is an acid?• An acid is a solution that has an excess of H+

ions. It comes from the Latin word acidus that means "sharp" or "sour".

• The more H + ions, the more acidic the solution.

Properties of an Acid

• Tastes Sour• Conduct Electricity• Corrosive, which means they break

down certain substances. Many acids can corrode fabric, skin, and paper

• Some acids react strongly with metals

• Turns blue litmus paper red• React with bases to form water and

salt.Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

Acids Affect Indicators, by changing their color

Blue litmus paper turns red in contact with an acid (and red paper stays red).

Acids have a

pH less

than 7

Uses of Acids• Acetic Acid = Vinegar• Citric Acid = lemons, limes, &

oranges. It is in many sour candies such as lemonhead & sour patch.

• Ascorbic acid = Vitamin C which your body needs to function.

• Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics.

• Car batteries

Effects of Acid Rain on Marble(marble is calcium carbonate)

George Washington:BEFORE acid rain

George Washington:AFTER acid rain

Acids Neutralize BasesHCl + NaOH → NaCl + H2O

-Neutralization reactions ALWAYS produce a salt and water.-Of course, it takes the right proportion of acid and base to produce a neutral salt.

Sulfuric Acid = H2SO4Highest volume

production of any chemical in the U.S. (approximately 60 billion pounds/year)

Used in the production of paper

Used in production of fertilizers

Used in petroleum refining; auto batteries

Nitric Acid = HNO3Used in the production

of fertilizersUsed in the production

of explosivesNitric acid is a volatile

acid – its reactive components evaporate easily

Stains proteins yellow (including skin!)

Hydrochloric Acid = HClUsed in the “pickling”

of steelUsed to purify

magnesium from sea water

Part of gastric juice, it aids in the digestion of proteins

Sold commercially as Muriatic acid

Phosphoric Acid = H3PO4A flavoring agent in

sodas (adds “tart”)Used in the

manufacture of detergents

Used in the manufacture of fertilizers

Not a common laboratory reagent

Acetic Acid = HC2H3O2 (also called Ethanoic Acid, CH3COOH)

Used in the manufacture of plastics

Used in making pharmaceuticals (drugs)

Acetic acid is the acid that is present in household vinegar

Coffee is a weak acid!

What is a base?

• A base is a solution that has an excess of OH- ions.

• Another word for base is alkali.

• Bases are substances that can accept hydrogen ions

Properties of a Base

• Feel Slippery• Taste Bitter• Corrosive• Can conduct electricity. (Think

alkaline batteries.)• Do not react with metals.• Turns red litmus paper blue.

Bases have a

pH greater than 7

Bases Neutralize Acids

Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl.

2 HCl + Mg(OH)2

MgCl2 + 2 H2OMagnesium salts can cause diarrhea (thus they are used as a laxative) and may also cause kidney stones.

Uses of Bases• Bases give soaps, ammonia,

and many other cleaning products some of their useful properties.

• The OH- ions interact strongly with certain substances, such as dirt and grease.

• Chalk and oven cleaner are examples of familiar products that contain bases.

• Your blood is a basic solution.

pH Scale

• pH is a measure of how acidic or basic a solution is.

• The pH scale ranges from 0 to 14. • Acidic solutions have pH values below 7• A solution with a pH of 0 is very acidic.• A solution with a pH of 7 is neutral.• Pure water has a pH of 7. • Basic solutions have pH values above 7.

pH Scale• A change of 1 pH unit represents a tenfold

change in the acidity of the solution. • For example, if one solution has a pH of 1 and

a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.

“DO NOW” FOR THURSDAY!

• Scientifically speaking, how are acids and bases similar and how are they different?