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Acids and Bases
What is an Acid?
Acid – a substance that produces H+ (hydrogen ions) in solution. It is the ability to produce the H+ ions that gives acids their characteristic properties.
Properties of Acids
• Acids taste sour. (never use taste to test for the presence of an acid. They can cause tissue damage.)
• Acids are electrolytes and can conduct electricity
Properties of Acids
• Acids are corrosive – they react strongly with metals and “eat away“ at the metals producing hydrogen gas. Contact with skin may result in severe burns and tissue damage
• Acids react with indicators, organic compounds that changes color in a n acid or a base.
Acids Affect Indicators, by changing their color
Blue litmus paper turns red in contact with an acid (and red paper stays
red).
Some Common AcidsName Formula Where Found
Acetic acid CH3COOH vinegar
Acetylsalicylic acid HOOC-C6H4-OOCCH3 aspirin
Ascorbic acid H2C6O6 citrus fruits
Boric acid H3BO3 eyewash solutions
Hydrochloric acid HCl gastric juice in stomach
Carbonic acid H2CO3 carbonated drinks
Sulfuric acid H2SO4 car batteries, fertilizers
How are acids used?• sulfuric acid – car batteries, fertilizer,
dehydrating agent (removes H2O from materials).
• Phosphoric Acid – fertilizers, used in soft drinks. Harmful to environment when added to detergents.
• Nitric acid – fertilizers, explosives.• Hydrochloric acid – used to clean surfaces in
industry. also known as muriatic acid.
What is a Base?
base – substance that produces hydroxide ions, OH-, in a solution.
Properties of Bases
• Most bases are crystalline solids.• In solution, bases feel slippery, like soap.• Bases taste bitter. • Bases are corrosive – contact with skin may result
in severe burns and tissue damageNEVER USE TASTE TO TEST FOR THE PRESENCE OF A
BASE. THEY CAN CAUSE TISSUE DAMAGE
Properties of Bases
• Bases are electrolytes and conduct electricity.• Bases react with indicators to produce a
predictable color change.
Common Bases and Their UsesName Formula Uses
Aluminum hydroxide Al(OH)3 deodorant, antacid
Calcium hydroxide Ca(OH)2 Leather production, manufacture of mortar and plaster
Magnesium hydroxide Mg(OH)2 laxative, antacid
sodium hydroxide NaOH drain cleaner, soap making
Ammonia NH3 household cleaner, fertilizer,production of rayon and nylon
Strength of Acids and Bases
• Strong acids – ionizes almost completely in solution (very soluble)
• Weak acids – acid that only partly ionizes in solution (slightly soluble)
• Strong base – dissociates completely in solution (very soluble)
• Weak base – base that only partly dissociates in solution (slightly soluble)
Strength and Concentration
• Concentration – the amount of acid or base dissolved in solution (g/100 mL)
• Strength – refers to the ease that the acid or base forms ions in solution. The more ions that are produced the stronger the acid or base
What is pH?pH is the measurement of
H3O+ (hydronium ions) in solution.
pH is a scale used to measure
how acidic or basic a solution is.
Below 7 is acidicAbove 7 is basic7 is neutral
Acids have a
pH less
than 7
Baseshave a
pH greater than 7
Acids have a
pH less
than 7
Baseshave a
pH greater than 7