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Acids, Bases, and Salts. Acids. Definition: An acid is a substance that produces H + ions in solution. Properties of acids. Tastes sour Corrosive: eats away at other materials. Causes burns and tissue damage Able to conduct electricity. Properties of Acids.
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Acids • Definition: An acid is a substance that produces H+ ions in solution
Properties of acids • Tastes sour • Corrosive: eats away at other materials. Causes burns and tissue damage • Able to conduct electricity
Properties of Acids • Forms H+ ions in solution • Examples include: gastric juices, vinegar, lemon juice, hydrochloric acid, aspirin, fertilizer, explosives • Litmus paper test: Turns litmus paper red
BAses • Definition: A base is a substance that produces OH- ions in solution
Properties of bases • Tastes bitter • Slippery feel. Strong bases can burn your skin • Able to conduct electricity
Properties of bases • Forms OH- ions in solution • Examples include: soap, ammonia, oven and drain cleaner, deodorant, laxatives • Litmus paper test: Turns litmus paper blue
Indicator • An indicator is a compound that changes color in the presence of an acid or base • Litmus paper is a common indicator. • It turns red in the presence of an acid • It turns blue in the presence of a base
Question You have probably seen commercials for antacids that describe how well these products neutralize excess stomach acid. • Would the pH of the antacid be higher or lower than 7? The answer is: higher than 7
Neutralization • Only a base can neutralize and acid • Only an acid can neutralize a base • Definition: Neutralization is a chemical reaction between an acid and a base
Neutralization • During a neutralization reaction, H3O+ ions from the acid combine with OH- ions from the base to produce water. • The reaction looks like this: H3O+ + OH- = 2H2O
Neutralization • As the reactive H3O+ and OH- ions combine to form water, the acidic and basic properties of the reactants are canceled out, or neutralized • The equation only accounts for half of the ions present in the solution, though. • What happens to the remaining ions? They react to form a salt.
Neutralization • Definition: A salt is a compound formed when the negative ions from an acid combine with the positive ions from a base.
neutralization • Neutralization reactions are ionic. The equation below show what happens to all of the ions during a neutralization reaction. HCl + NaOH = H2O + NaCl (acid) (base) (water) (salt)
Neutralization What do you think you will get if you combine hydrochloric acid with potassium hydroxide? HCl + KOH = ? (acid) (base) Answer: HCl + KOH = H2O + KCl (acid) (base) (water) (salt)
Salts • Many substances you come into contact with everyday are salts. • The most common is NaCl, table salt. • Most salts are composed of a metal and a nonmetal other than oxygen. • Salts can also be composed of a metal and a polyatomic ion. Ammonium salts contain the polyatomic ion NH4+ rather than a nonmetal.
salts • Salts also form when metals react with acids. Hydrogen gas is released during such reactions: H2SO4 + Zn = ZnSO4 + H2 (acid) (metal) (salt) (hydrogen gas)
Neutralization reactionsHave the following properties: • Water is formed • Precipitate (salt solid) is formed • Color can change • Heat can be given off • Gas can be given off