Review of Acids, Bases, & Salts
Has H in the formula Produces H+ as the only positive ion in solution Arrhenius Acid
Inorganic – formula starts with H (except H2O & H2O2) Organic – formula ends with COOH Formula of an Acid
Properties of Acids Sour Taste Electrolytes React with bases to form a salt + H2O Turn litmus RED React with most metals to produce H2(g) Properties of Acids
Ionization of an Acid: Why is it so weird? Because acids are covalent! Ionization of an Acid: Why is it so weird?
HCl H+ + Cl- HCl + H2O H3O+ + Cl- Ionization of an Acid or Arrhenius format or HCl + H2O H3O+ + Cl- Bronsted-Lowry format Ionization of an Acid
HCl HNO3 HBr HClO4 HI H2SO4 Six strong acids?
Ionization of a weak base: Why is it so weird? Because weak bases are covalent! Ionization of a weak base: Why is it so weird?
Autoionization of water H2O H+ + OH- Autoionization of water
Arrhenius Base (Strong bases) Has OH in the formula Produces OH- as the only negative ion in solution Arrhenius Base (Strong bases)
LiOH Ca(OH)2 NaOH Sr(OH)2 KOH Ba(OH)2 Six strong bases?
Formula of a Strong Base Has format M(OH)x M is a metal X can be 1, 2, or 3 Formula of a Strong Base
Properties of Bases Bitter Taste Slippery Feel Electrolytes React with acids to form a salt + H2O Turn litmus BLUE Properties of Bases
Ionization of a strong base NaOH Na+ + OH- Ionization of a strong base
Ionization of NH3, a weak base NH3 + H2O NH4+ + OH- Ionization of NH3, a weak base
Metal + Nonmetal Formula of a Salt
Write the formula of potassium sulfate K+ & (SO4)2- K2SO4 Write the formula of potassium sulfate
Electrolytes Solutions conduct – they contain ions Acids (HX), bases (MOH), & salts (MX) are electrolytes Electrolytes
Solutions of covalent compounds (all nonmetals), excepting the acids and the weak bases. They do NOT conduct. NONelectrolytes
Identify the electrolytes Yes - B Yes - B LiOH CH3COOH C6H12O6 NaNO3 H2SO4 CH3OH Ca(OH)2 HCl C8H18 Al(OH)3 HNO3 CH3CH2COOH K2SO4 CH3CHOHCH3 CH3OCH3 H3PO4 Mg(OH)2 CH3CH2OH Yes - A Yes - A Yes - A No Yes - S Yes - S Yes - A No No No Yes - A Yes - B Yes - A Yes - B No No
0-14 Acidic: 0 to 7, Neutral: 7 Basic: 7-14 pH scale
pH = -log[H+] pH = ?
How do you get [H+] from pH? [H+] = 10-pH How do you get [H+] from pH?
pOH = -log[OH-] pOH = ?
pK = -log[K] pK = ?
pH = 0 Most acidic on pH scale
pH = 14 Most basic on pH scale
Hydroxide ion OH-
Hydrogen ion or Proton H+
Hydronium ion. Bronsted-Lowry form of H+. Used interchangeably with H+ . H3O+
[H+] [OH-] Acidic Solution
[OH-] [H+] Basic Solution
14, at 25C pH + pOH = ?
If the pH changes from 3 to 5, how does the [H+] change? The pH changes by 2, so the [H+] changes by 102 or 100X. Since the pH went up, it became LESS acidic. The new solution has a [H+] 100 times less than the original solution. It is 1/100 of the original [H+]. If the pH changes from 3 to 5, how does the [H+] change?
How can pH be safely tested? Instrumental – use pH meter Indicators – use a series of indicators to narrow down the pH range Test acids with metals (NOT Cu, Ag, or Au) How can pH be safely tested?
Proton Donor Bronsted-Lowry Acid
Proton Acceptor Bronsted-Lowry Base
Bronsted-Lowry Acids & Bases HCl + H2O H3O+ + Cl- Acid Base c. acid c. base Bronsted-Lowry Acids & Bases
Complete or almost complete ionization. Strong Acids & Bases
Concentration of ions in .4 M HCl Strong acid HCl H+ + Cl- Concentration of H+ = 0.4 M Concentration of Cl- = 0.4 M Concentration of ions in .4 M HCl
Ionization occurs only to a slight extent, a few percent. Weak Acids & Bases
Reactions of Acids with Metals Metal + Acid H2(g) + salt Reactions of Acids with Metals
Zn(s) + 2HCl H2(g) + ZnCl2 Zn(s) + HCl ?
2Al(s) + 6HCl 3H2(g) + 2AlCl3 Al(s) + HCl ?
Neutralization Reactions Acid + Base Salt + H2O Neutralization Reactions
H+ + OH- H2O Net Ionic Equation for strong acid/strong base Neutralization Reactions
Moles H+ = Moles OH- At equivalence point
Molarity = Moles solute Liters of soln Molarity (M)
NYS Titration Equation MaVa = MbVb This equation only works when the number of H’s on the acid EQUALS the number of OH’s on the base! NYS Titration Equation
naMaVa = nbMbVb Titration Equation This equation works when the number of H’s on the acid does NOT equal the number of OH’s on the base! na = number of acidic H’s in acid. nb = number of OH’s in base. Titration Equation
-log[H+] or –log[H3O+] pH
-log[OH-] pOH
Equilibrium Constant Expression for aA(aq) + bB(aq) cC(aq) + D(aq) [C]c[D]d [A]a[B]b K = Equilibrium Constant Expression for aA(aq) + bB(aq) cC(aq) + D(aq)
Equilibrium Constant Expression for aA(s) + bB(aq) cC(s) + D(aq) [D]d [B]b K = Equilibrium Constant Expression for aA(s) + bB(aq) cC(s) + D(aq)
-logK pK
14 pOH + pH =
1.0 X 10-14 [OH-] X [H+] =
The pH = The pOH = The [OH-] = 3 11 1 X 10-11 If the [H+] = 1 X 10-3
Substance that changes color over a narrow pH range. Indicator
Molarity H2SO4 Vs. Molarity H+ H2SO4 2H+ + SO42- [H+] = 2[H2SO4] 2M H2SO4 4M H+ Molarity H2SO4 Vs. Molarity H+
naMaVa = nbMbVb (1)X(20.0 mls) = (1).250M(50.0mls) What is the concentration of a hydrochloric acid solution if 50.0 mL of a 0.250 M KOH solution are needed to neutralize 20.0 mL of the HCl solution of unknown concentration?
(1.50 M)(10.62 mls) = X(20.20 mls) Acid 1.50 M Base ? M Final Volume 16.07 24.25 Initial Volume 5.45 4.05 Amount Used 10.62 20.20 (1.50 M)(10.62 mls) = X(20.20 mls)
Why do different salts produce solutions with different pHs? Hydrolysis of the ions! Why do different salts produce solutions with different pHs?
Reaction of ions with water to produce H+ or OH- Hydrolysis
Which anions undergo hydrolysis? Anions of weak acids: they produce basic solutions. C2H3O2- + H2O HC2H3O2 + OH- Which anions undergo hydrolysis?
Which cations undergo hydrolysis? Cations of weak bases: They produce acidic solutions. NH4+ + H2O H3O+ + NH3 Which cations undergo hydrolysis?