Acids & Bases
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Transcript of Acids & Bases
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?