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Characteristics of Acids: Table K Electrolytes pH scale: less than 7 Litmus: RED Phenolphthelein: colorless Contains a high concentration of Hydrogen ions (H + ) or Hydronium Ion (H 3 O + ) H 2 O + H + = H 3 O + React with certain metals to produce hydrogen gas (H 2 ) – TABLE J.
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Characteristics of Acids: Table K • Electrolytes • pH scale: less than 7 • Litmus: RED • Phenolphthelein: colorless • Contains a high concentration of Hydrogen ions (H+) or Hydronium Ion (H3O+) H2O + H+ = H3O+ • React with certain metals to produce hydrogen gas (H2) – TABLE J
Metal must be higher than H2 to react
Characteristics of Bases: Table L • Electrolytes • pH scale: greater than 7 • Litmus: BLUE • Phenolphthelein: pink • Contains a high concentration of Hydroxide ions (OH-) • Tastes bitter; feels slippery/soapy
Characteristics of Salts • An ionic compound that has positive ions other than hydrogen (H+) and negative ions other than hydroxide (OH-). • Example: NaCl (Na+ and Cl-). • Salts conduct electricity (salts are electrolytes). • ACIDS, BASES & SALTS ARE ELECTROLYTES
Beware of Tricks . . . • Organic Acids have a functional group –COOH, so when you see a compound with carbon and this functional group it is an acid!! Ex: CH3COOH • Alcohols have a functional group –OH (hyroxyl), not OH- (hydroxide); alcohols are not bases!! Ex: CH3OH
Strong Acids & Bases • HCl • HBr • HI • HNO3 • H2SO4 • HClO3 • HClO4 • NaOH • KOH • Ca(OH)2 • LiOH • RbOH • CsOH • Ba(OH)2 NH3 is a weak base!!
ARRHENIUS THEORY OF ACIDS & BASES • An Arrhenius Acidhas H and releases H+ in an aqueous solution. • The H+ ion is the only positive ion in these solutions. The H+ ions are always attached to H2O forming H3O+ (hydronium ions). • An Arrhenius basehas OH (hydroxide) and releases OH- (hydroxide ion) in an aqueous solution. • The OH- ion is the only negative ion in these solutions.
Bases Accept Acids Donate Bases: H+ acceptor (proton acceptor) Acids: H+ donor (proton donor) Bronsted-Lowry Theory (Alternate Acid-Base Theory)
Conjugate Acid Base Pairs 1. NH4+ + OH- → NH3 + H2O 2. H3PO4 + NO2- → HNO2 + H2PO4- 3. HI (aq) + H2O (l) → H3O+ (aq) + I- (aq) • Some substances can sometimes act like an acid and sometimes act like a base. Examples are H2O & HSO4-
Neutralization Reactions • ACID + BASE = WATER + SALT (IONIC SOLID)
Titration is a lab process in which a volume of a solution of known concentration is used to determine the concentration of another solution. MAVA =MBVB Titration
Example 1: • What is the molarity of HCl (aq) if 10. milliliters of 4.0 M NaOH (aq) neutralizes exactly 20. milliliters of HCl (aq)?
Example 2: • What is the molarity of NaOH (aq) if 10. milliliters of 2 M HBr (aq) neutralizes exactly 5. milliliters of NaOH (aq)?
pH Scale • Movement from one whole number to the next represents a change by a power of 10. • Acids: 1-7, [H3O+] > [OH-] • Neutral: 7, [H3O+] = [OH-] • Bases: 7-14, [H3O+] < [OH-]
Meaning of pH & pOH pH = -log[H+] • pH = -log[1.0X10-5] = -(-5) = 5 • The solution is acidic. pOH = -log[OH-] • pOH is the concentration of OH- instead of the concentration of H+ • pH + pOH = 14