acids and bases ch 16. i. properties of acids and bases a. acids –1. taste sour (think lemons:...
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C. The Arrhenius Model 1. Svante Arrhenius was 1 st person to recognize the properties of acids and bases. –a. Arrhenius Acid- produces H + ions in solution HCl(aq) → H + (aq) + Cl - (aq) –b. Arrhenius Base- produces OH - ions in solution NaOH(aq) → Na + (aq) + OH - (aq)TRANSCRIPT
Acids and Bases
Ch 16
I. Properties of Acids and Bases
• A. Acids– 1. Taste sour (think
lemons: citric acid)– 2. React with metals to
produce hydrogen– 3. Conduct electricity
• B. Bases– 1. Taste bitter (think
Milk of Magnesia)– 2. Feel slippery (like
soap)– 3. Conduct electricity– 4. Can be caustic
C. The Arrhenius Model
• 1. Svante Arrhenius was 1st person to recognize the properties of acids and bases.– a. Arrhenius Acid- produces H+ ions in solution
• HCl(aq) → H+(aq) + Cl-(aq)– b. Arrhenius Base- produces OH- ions in solution
• NaOH(aq) → Na+(aq) + OH-(aq)
D. Brønsted- Lowry Model
• 1. Johannes Brønsted and Thomas Lowry developed a more general definition of acids and bases.– a. Brønsted- Lowry acid- a proton (H+) donor– b. Brønsted- Lowry base- a proton (H+) acceptor– c. Conjugate base- the remaining substance after
an acid has donated its proton– d. Conjugate acid- the remaining substance after a
base has accepted a proton.
Example• HCl(aq) + H2O(aq) → H3O+(aq) + Cl-(aq)
BL acid BL base Conj Conj acid base
• HSO4-(aq) +H2O(aq) → H2SO4(aq) + OH-(aq)
BL base BL acid Conj Conj acid base
H3O+ is called the hydronium ion.
Problems to try
• 1. Which of the following represent conjugate acid-base pairs?– a. HF, F- b. NH4
+, NH3 c. HCl, H2O
• 2. Write the conjugate base for each of the following:– a. HClO4 b. H3PO4 c. CH3NH3
+
C. Acid Strength
• 1. strong acids and bases: break apart 100% into their ions in solution
• 2. weak acids and bases: only 5% breaks down into ions in solution.
Hydronium Ion Concentration
• [H3O+]
– It’s sometimes written as [H+] as a short cut, because we are just concerned about the H.
• Tells how concentrated the acid/ base is in terms of MOLARITY!!!!!
pH
• pH gives the relative strength of an acid or base!
• pH = -log [H+]• pOH = -log [OH-]• pH + pOH = 14• [H+] • [OH-] = 1 × 10-14
• 3. Strong Acids– a. have weak conjugate bases– HClO4
– HI– HBr– H2SO4
– HCl– HNO3
– b. Diprotic acids- an acid that can give 2 protons• H2PO4(aq) → H+(aq) + HPO4
-(aq)
– HPO4-(aq) → H+(aq) + PO4
2-(aq)
– c. Triprotic acids- an acid that can give 3 protons• H3PO4(aq) → H+(aq) + H2PO4
-(aq)
– H2PO4-(aq) → H+(aq) + HPO4
2-(aq)
» HPO42-(aq) → H+(Aq) + PO4
3-(aq)
4. Strong BasesHave a weak conjugate acid
Alkali Metal Hydroxides• NaOH• KOH• LiOH• RbOH• CsOH
Alkaline Earth Metal Hydroxides
• Ca(OH)2
• Ba(OH)2
• Sr(OH)2
• While these 3 are strong bases, they are not very soluble in water.