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Unit 10- Acids and Bases. Acidity Alkalinity Arrhenius acid Arrhenius base Bronsted-Lowry acid Bronsted-Lowry base Buffer Electrolyte. Hydrogen ion Hydronium ion Indicator Neutralization pH scale Salt Titration. Properties of Acids. Have sour taste

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unit 10 acids and bases
Unit 10- Acids and Bases
  • Acidity
  • Alkalinity
  • Arrhenius acid
  • Arrhenius base
  • Bronsted-Lowry acid
  • Bronsted-Lowry base
  • Buffer
  • Electrolyte
  • Hydrogen ion
  • Hydronium ion
  • Indicator
  • Neutralization
  • pH scale
  • Salt
  • Titration
properties of acids
Properties of Acids
  • Have sour taste
    • ***take my word, don’t taste lab chemicals
  • Can conduct electric current in solution
    • Electrolytes
    • Good conductor= strong acid
    • Poor conductor= weak acid
  • Turns blue litmus paper red “blue to red a-cid”
  • Most common acids are liquid or gas
  • React with metals to produce H2 gas
    • Above H2 in Table J will react (single-replacement)
  • React with bases to form salt and water
    • Neutralization (double-replacement
  • Can generate hydronium ions H3O+ in water
  • pH less than 7
acids
Acids
  • Sulfuric- car batteries
  • Ascorbic- tomatoes
properties of bases
Properties of Bases
  • Have bitter taste
    • ***take my word, don’t taste lab chemicals
  • Can conduct electric current in solution
    • Electrolytes
    • Good conductor= strong base
    • Poor conductor= weak base
  • Most common bases are solid
  • React with acids to form salt and water
    • Neutralization (double-replacement
  • Can generate hydroxide ions OH- in water
  • Turns red litmus paper blue “blue base”
  • pH greater than 7
bases
Bases
  • Sodium bicarbonate
acid and base strength
Acid and Base Strength
  • Due to degree of ionization
  • Complete dissociation-strong acid or base
definitions of acids and bases
Definitions of Acids and Bases
  • Arrhenius Theory-
    • Arrhenius acid- produces H+ or H3O+ as the only positive ions in solution
      • Hydrogen ions will attract to water molecule and form hydronium ions
    • Arrhenius base- produces OH- ions in solution
      • Except!!! Not all bases have OH- ions
  • Drawbacks:
    • Limited to aqueous solutions
    • Can’t classify amphoteric substances (substances that act as bases and acids)
slide8

Arrhenius acid is a substance that produces H+ (H3O+) in water

Arrhenius base is a substance that produces OH- in water

definitions of acids and bases con t

A Brønsted-Lowry acid is a proton donor

A Brønsted-Lowry base is a proton acceptor

Definitions of Acids and Bases con’t
  • BrØnsted-LowryTheory-
    • B-L acid- proton donor
    • B-L base- proton acceptor
    • Proton = hydrogen ion that has lost its electron

conjugateacid

conjugatebase

acid

base

definitions of acids and bases con t1
Definitions of Acids and Bases con’t
  • All Arrhenius acids are also B-L acids
  • B-L bases expand the substances that can be considered bases
naming acids
Naming acids
  • If an acid molecule forms 1 H ion it’s a:
    • Monoprotic acid (HCl)
  • If an acid molecule forms 2 H ions it’s a:
    • Diprotic acid (H2SO4)
  • If an acid molecule forms 3 H ions it’s a:
    • Triprotic acid (H3PO4)
naming acids con t
Naming acids con’t
  • For binary acids:
    • Hydro + element name – ine + ic + acid
    • Ex: HCl- hydrochloric acid
    • Try HF- _________________________
  • For ternary acids:containing H, O and another element
    • 3rd element name, modify to end in –ic or –ous + acid
    • Ex: HNO3- nitric acid nitrogen –ogen + ic + acid
    • Try HNO2- _____________________
naming bases
Naming bases

No oxygen 

  • Name of positive ion + hydroxide
    • Ex: Ba(OH)2- barium hydroxide
    • Try KOH- ____________________

More oxygen 

Less oxygen 

reactions with acids and bases
Reactions with acids and bases
  • Acids and metals-
    • Use Table J in Ref Tables
    • Acid will react with anything above H2
    • Single replacement rx’s

Zn(s) + 2HCl(aq)  H2(g) + ZnCl2(aq)

  • Neutralization reactions-
    • Arrhenius acid + Arrhenius base  salt + water
    • Equivalence pt- pt at which neutralization is complete; when H30+ ion = OH- ions
neutralization rx
Neutralization Rx
  • Words:

Hydrochloric acid + sodium hydroxide  water + sodium chloride

  • Chemical formulas:

HCl(aq) + NaOH(aq)  H2O(l) + NaCl(aq)

  • Ions:

H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq)  H2O(l) + Na+(aq) + Cl-(aq)

  • Omitting spectator ions:

H+(aq) + OH-(aq)  H2O(l) or

H3O+(aq)+ OH-(aq)  2H2O(l)

neutralization rx s con t
Neutralization Rx’s con’t
  • Diprotic acid + dihydroxy base makes 2 water molecules
    • Ex: Ca(OH)2 + H2SO4 2H2O + CaSO4
  • Acids and bases with unequal H+ and OH- needs to be balanced
    • Ex: ___Mg(OH)2 + __HCl  __H2O + ___MgCl2

(two) (one)

  • Salts produced- ionic substance with a metal and nonmetal or polyatomic ion
titrations
Titrations
  • Process of adding a measured volume of an acid or base of known concentration to an acid or base of unknown concentration until neutralization occurs
  • Cacid x Vacid = Cbase x Vbase

(known) (known) = (unknown) (known)

molarity x volume = molarity x volume

  • Standard solution= soln of known concentration
  • There needs to be a 1:1 ratio of H+ to OH-
    • Diprotic ex: 2.5M H2SO4 = 5M H+
    • Triprotic ex: 2MH3PO4 = 6M H+
    • Dihydroxy base ex: .5MBa(OH)2 = 1M OH-
acidity and alkalinity of solutions
Acidity and Alkalinity of Solutions
  • Relative strength of an acid or base in terms of their H+ or OH- concentrations
  • H2O  H+ + OH-
    • Le Chateliers principle [H+] = [OH-]
    • If one increases the other decreases
      • If you add HCl to water H+ increases so it becomes more acidic
ph scale
pH scale
  • Expresses the strength of acids and bases
  • Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H+ (or OH-) ion.
  • pH change of 1 is a 10 fold increase or decrease in ions
ph indicators
pH indicators
  • Substance that changes its color when it gains or loses a proton (H+ ion)
  • Universal indicators are a mix of a few indicators
  • pH meter- electric instrument with probes sensitive to H3O+ creates voltage between probes
buffers
Buffers
  • Solutions that resist change in pH
  • Weak acid or base
  • Usually a weak acid and its conjugate base
  • Stabilizes pH
    • Foods, shampoo, antacids, blood
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