acids and bases
DESCRIPTION
Acids and Bases. Acids and Bases. Acid : a substance that, when dissolved in water, increases the concentration of H + (protons) HCl H + + Cl - HCl + H 2 O H 3 O + + Cl - Strong acid : an acid that completely ionizes/dissociates in water HNO 3 + H 2 OH 3 O + + NO 3 - - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/1.jpg)
Acids and Bases
![Page 2: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/2.jpg)
Acids and Bases
• Acid: a substance that, when dissolved in water, increases the concentration of H+ (protons)• HCl H+ + Cl-
• HCl + H2O H3O+ + Cl-
• Strong acid: an acid that completely ionizes/dissociates in water• HNO3 + H2O H3O+ + NO3
-
• Strong electrolyte
H2O
![Page 3: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/3.jpg)
![Page 4: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/4.jpg)
![Page 5: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/5.jpg)
• Strong Acids:• Hydrochloric Acid HCl
• Nitric Acid HNO3
• Sulfuric Acid H2SO4
• Perchloric Acid HClO4
• Hydrobromic Acid HBr• Hydroiodic Acid HI
![Page 6: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/6.jpg)
![Page 7: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/7.jpg)
• Weak Acid: an acid that only partially ionizes/dissociates in water• CH3COOH(aq) CH3COO-(aq) + H3O+(aq)
• Weak electrolytes• Weak Acids:
• Phosphoric acid H3PO4
• Acetic Acid CH3COOH
• Carbonic Acid H2CO3
• Hydrocyanic Acid HCN
• Benzoic Acid C6H5COOH
![Page 8: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/8.jpg)
![Page 9: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/9.jpg)
Polyprotic Acids
• Polyprotic acids: acids that can release more than one H+
• Sulfuric Acid• H2SO4(aq) HSO4
-(aq) + H3O+(aq)
• HSO4-(aq) SO4
2-(aq) + H3O+(aq)
![Page 10: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/10.jpg)
Problem
• Write out the equation(s) for the ionization of phosphoric acid, H3PO4, in water
![Page 11: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/11.jpg)
Bases
• Base: a substance that, when put in water, increases the concentration of OH- ions or a substance that accepts H+ ions• NaOH(aq) Na+(aq) + OH-(aq)
• Strong Bases: bases that completely ionize in water
![Page 12: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/12.jpg)
![Page 13: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/13.jpg)
![Page 14: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/14.jpg)
• Weak Bases: bases that only partially ionize in water• Ammonia: NH3
• Pyridine: C5H5N
![Page 15: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/15.jpg)
![Page 16: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/16.jpg)
![Page 17: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/17.jpg)
Each acid has a conjugate base and every base has a conjugate acid
conjugate acid-base pair 1
HA + B A− + BH+
conjugate acid-base pair 2
Congugate Acid-Base Pairs
![Page 18: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/18.jpg)
![Page 19: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/19.jpg)
Problems
Identify the conjugate bases for the following:
1) HBr
2) H2S
3) H2CO3
Identify the conjugate acids for the following
1) NO2-
2) NH3
3) OH-
![Page 20: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/20.jpg)
In the following equations, identify the conjugate acid and base pairs:
1) HCl + H2O H3O+ + Cl-
1) C5H5N + H2O C5H6N+ + OH-
![Page 21: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/21.jpg)
![Page 22: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/22.jpg)
Neutralization Reactions
• When strong acids and bases in aqueous solution react with each other, they form water and a salt
• HX(aq) + MOH(aq) HOH(l) + MX(aq)
• HCl(aq) + NaCl(aq) H2O(l) + NaCl(aq)
Water Salt
![Page 23: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/23.jpg)
Problems
Write out the molecular, total ionic, and net ionic equations for the reactions of the following acids and bases
1) HBr and KOH
2) HCl and Mg(OH)2
3) H2SO3 and NaOH
![Page 24: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/24.jpg)
![Page 25: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/25.jpg)
![Page 26: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/26.jpg)
Acid Ionization Constant
• Acid Ionization Constant (Ka): the equilibrium constant for the ionization reaction of an acid with water• HA + H2O A- + H3O+
• Large Ka = Strong acid
• Small Ka = Weak acid
![Page 27: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/27.jpg)
![Page 28: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/28.jpg)
Questions
1) Write the equilibrium constant expression for the dissociation of HCN (hydrocyanic acid) in water
2) Write the equilibrium expression for the dissociation of HF in water
3) If the Ka for HCN is 4.9 x 10-10 and the Ka for HF is 7.2 x 10-4, which acid is stronger?
![Page 29: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/29.jpg)
4) Predict whether the equilibrium for each of the following reactions favors the reactants or products.
a) H3PO4(aq) + H2O(l) H3O+(aq) + H2PO4(aq)
b) NH4+(aq) + H2O(l) H3O+(aq) + NH3(aq)
![Page 30: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/30.jpg)
Base Ionization Constant
• Base Ionization Constant (Kb): the equilibrium constant for the ionization reaction of a base with water• B + H2O OH- + BH+
• Large Kb = Strong base
• Small Kb = Weak base
![Page 31: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/31.jpg)
![Page 32: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/32.jpg)
Autoionization of Water
![Page 33: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/33.jpg)
Autoionization of Water• Also called “Self Ionization”• About 1 out of every 10 million water
molecules form ions through self ionization
H2O H+ + OH–
H2O + H2O H3O+ + OH–
• All aqueous solutions contain both H3O+ and OH–
![Page 34: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/34.jpg)
Ion Product Constant for Water
• Ion Product Constant for Water (Kw): the numerical value obtained by multiplying the molar concentrations for hydronium and hydroxide ions present in pure water at 25°C• KKww = [H = [H33OO++][OH][OH--] = 1.00 x 10] = 1.00 x 10-14-14 at 25 at 25 ooCC• the concentration of H3O+ and OH– are equal
in pure water• [H3O+] = [OH–] = 10-7M @ 25°C
![Page 35: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/35.jpg)
Ion Product of Water• the product of the H3O+ and OH–
concentrations is always the same number
• Kw =[H3O+][OH–] = 1.00 x 10-14 @ 25°C– if you measure one of the concentrations,
you can calculate the other
• as [H3O+] increases the [OH–] must decrease so the product stays constant– inversely proportional
![Page 36: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/36.jpg)
[H+] vs. [OH-]
OH-H+ H+ H+ H+ H+
OH-OH-OH-OH-
[OH-]10-14 10-13 10-11 10-9 10-7 10-5 10-3 10-1 100
[H+] 100 10-1 10-3 10-5 10-7 10-9 10-11 10-13 10-14
Even though it may look like it, neither H+ nor OH- will ever be 0
Acid Base
![Page 37: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/37.jpg)
Acidic and Basic Solutions• Neutral solutions have equal [H3O+] and [OH–]
• [H3O+] = [OH–] = 1 x 10-7
• acidic solutions have a larger [H3O+] than [OH–]• [H3O+] > [OH–]• [H3O+] > 1 x 10-7; [OH–] < 1 x 10-7
• basic solutions have a larger [OH–] than [H3O+]• [H3O+] < [OH–]• [H3O+] < 1 x 10-7; [OH–] > 1 x 10-7
![Page 38: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/38.jpg)
Questions
1) Calculate the [OH] at 25°C when the [H3O+] = 1.5 x 10-9 M, and determine if the solution is acidic, basic, or neutral
2) Calculate the [H3O+] at 25°C in a solution that has a [OH] 1.3 x 10-10 M and determine if the solution is acidic, basic, or neutral
3) Calculate the [H3O+] at 25°C in a solution that has a [OH] 1.0 x 10-7 M and determine if the solution is acidic, basic, or neutral
![Page 39: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/39.jpg)
pH and pOH
• Acidic solutions• pH < 7
• Basic solutions• pH > 7
• Neutral solutions• pH = 7
![Page 40: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/40.jpg)
![Page 41: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/41.jpg)
• pH is a measure of the concentration of H+ or H3O+ in solution
• pH = -log [H+] OR pH = -log [H3O+]
• [H3O+] = 10-pH
• pOH is a measure of the concentration of OH- in solution• pOH = -log [OH-]• [OH-] = 10-pOH
• pH + pOH = 14
![Page 42: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/42.jpg)
Problems
1) What is the pH for an HCl solution with an [H3O+] = 2.3 x 10-2?
2) What is the pH of an NaOH solution with an [H3O+] = 3.39 x 10-10?
3) What is the pH of a KOH solution with a [OH-] = 1.1 x 10-2?
4) What is the [H3O+] for a solution with a pH of 8.45. What is the [OH-]?
![Page 43: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/43.jpg)
• Electrolytes: solutes that separate into ions when dissolved in water (they’re soluble)– Have the ability to conduct electricity– 2 types
• Strong electrolytes• Weak electrolytes
Classification of Water Soluble Substances
![Page 44: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/44.jpg)
• Strong electrolytes: solutes that completely dissociates into ions when dissolved in water– Examples: NaCl,
MgBr2, HCl
– Strong electrical conductors
– Strong electrolyte(aq or s) → Cation+(aq) + Anion-(aq) – Example: NaCl(s) → Na+(aq) + Cl-(aq)
![Page 45: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/45.jpg)
• Weak Electrolytes: solutes that, when dissolved in water, only partially dissociates into ions– Examples: HF, NH3,
acetic acid – Weak electrical
conductors
– Weak electrolyte(aq) ↔ Cation+(aq) + Anion-(aq)
– Example: HF(aq) ↔ H+(aq) + F-(aq)
![Page 46: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/46.jpg)
• Nonelectrolytes: solutes that dissolve in water without separating into ions– Examples: sucrose,
ethanol– Do not conduct electricity
Nonelectrolyte (s or l) → Nonelectrolyte(aq)Example: C12H22O11(s) → C12H22O11(aq)
![Page 47: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/47.jpg)
Problems
1) The following salts are strong electrolytes. Write a balanced equation for their dissociation in water
a) LiBr
b) FeCl32) HCN is a weak acid. Write a balanced
equation for its dissociation in water
3) Do you expect Fructose (C6H12O6) to be a strong electrolyte, weak electrolyte, or nonelectrolyte? Write a balanced equation for its solvation in water
![Page 48: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/48.jpg)
Titration
• Titration: a procedure for the quantitative analysis of a substance of unknown concentration whereby a measured quantity of another substance, of know concentration, is completely reacted with the with the original substance.– Often used to determine the
concentration of acids and bases
![Page 49: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/49.jpg)
![Page 50: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/50.jpg)
• Equivalence point: the point in a titration at which one reactant has been exactly consumed by the by the addition of another reactant– Midpoint of vertical rise– Occurs at pH = 7 in a strong acid-strong base titration– [H3O+] = [OH-]
![Page 51: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/51.jpg)
Indicators
• Acid-Base Indicator: a chemical that changes color with a change in pH– Added to solutions in small amounts in order
to determine to solution’s pH visually
– Usually organic compounds
– Weak acid or base
– establishes an equilibrium with the H2O and H3O+ in the solution
![Page 52: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/52.jpg)
HInd(aq) + H2O(l) Ind(aq) + H3O+
(aq)
![Page 53: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/53.jpg)
53
Phenolphthalein
![Page 54: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/54.jpg)
Bromocresol Green
Yellow Green Blue
![Page 55: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/55.jpg)
Methyl Red
![Page 56: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/56.jpg)
![Page 57: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/57.jpg)
Questions
1) You have 25.0 mL of a HCl solution of unknown concentration. If you titrate your acid with 17.3 mL of a 0.877 M NaOH solution, what is the concentration of your acid?
2) You also have 25.0 mL of a sulfuric acid solution. If you titrate this solution with 32.1 mL of a 1.50 M KOH solution, what is the concentration of your acid?
![Page 58: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/58.jpg)
![Page 59: Acids and Bases](https://reader035.vdocument.in/reader035/viewer/2022070405/56813d34550346895da6f8c5/html5/thumbnails/59.jpg)