Acids, Bases, and Salts All ionic compounds can be classified as one of these three. All are types of electrolytes (conduct electricity in aqueous solutions) Acids and bases are found many places in everyday life: Acids: lemon juice, car batteries, vinegar, orange juice Bases: ammonia, lye, blood

Acids Taste sour Begin with H Found in many foods and drinks Turn blue litmus paper red pH 0-6.9 Corrosive react with metals to generate H2(g) react with metal oxides and hydroxides to form salts and water Forms H+ (or H30+)ions in solutions Hydrogen Hydronium

Bases Bitter Normally end in OH Turn red litmus paper blue pH 7.1-14 Found in many cleaning products Slippery Corrosive react with acids to form salts and water Forms OH- ions in solution Hydroxide

Acids and Bases Neutral: H+ = OH- Acidic: H+ > OH- Basic: H+ < OH- ↑H+ = ↓OH- = more acidic = ↓ pH ac idic ↓H+ = ↑OH- = more basic = ↑ pH

Water = Neutral H2O = HOH HOH → H+ + OH- Free Hydrogen ion bonds with water molecule to form Hydronium ion H+ and H3O+ used interchangeably

Hydronium Ion = Hydrogen Ion Self ionization - two water molecules react to form a hydronium ion (H3O+) and hydroxide ion. H20 → H+ + OH-

pH scale Shows the strength of acid or base on a scale of 0-14. Numbers below 7 = acids…the lower the number, the more acidic Numbers above 7 – bases…the higher the number the more basic.

pH and pOH Formula: pH + pOH = 14 Ex. 1) If the pH = 2, what is pOH?

pH and pOH Formula: pH + pOH = 14 Ex. 1) If the pH = 2, what is pOH?

pH and pOH Formula: pH + pOH = 14 Ex. 1) If the pH = 2, what is pOH?

pH and pOH Formula: pH + pOH = 14 Ex. 2) If the pH = 4, what is the pOH?

pH and pOH Formula: pH + pOH = 14 Ex. 2) If the pH = 4, what is the pOH? 4 + pOH = 14 pOH = 14 – 4 pOH = 10

pH and pOH Formula: pH + pOH = 14 Ex. 3) If the pOH = 7, what is the pH?

pH and pOH Formula: pH + pOH = 14 Ex. 3) If the pOH = 7, what is the pH? pH + 7 = 14 pH = 14 – 7 pH = 7

Calculating pH Formula: pH = -log [ H+ ] OR pH = -log [ H3O+ ] You can calculate pH by finding the negative logarithm of the concentration of hydrogen ions.

Calculating pH Ex. 4) A solution contains 1.0 x 10-8 mol/L of H+ ions, what is the pH of this solution? Formula: pH= -log [H+]

Calculating pH Ex. 4) A solution contains 1.0 x 10-8 mol/L of H+ ions, what is the pH of this solution? Formula: pH= -log [H+] pH = -log (1.0 x 10-8) In calculator pH = -log (1.0 E -8)

Calculating pH Ex. 4) A solution contains 1.0 x 10-8 mol/L of H+ ions, what is the pH of this solution? Formula: pH= -log [H+] pH = -log (1.0 x 10-8) In calculator pH = -log (1.0 E -8) pH = 8.00 =

Calculating pH Ex. 4) A solution contains 1.0 x 10-8 mol/L of H+ ions, what is the pH of this solution? Formula: pH= -log [H+] pH = -log (1.0 x 10-8) In calculator pH = -log (1.0 E -8) pH = 8.00 = Base

Calculating pH Ex. 5) A solution contains 3.5 x 10-5 M of H+ ions, what is the pH of the solution? Formula: pH= -log [H+]

Calculating pH Ex. 5) A solution contains 3.5 x 10-5 M of H+ ions, what is the pH of the solution? Formula: pH= -log [H+] pH= -log (3.5 x 10-5) In calculator pH= -log (3.5 E -5)

Calculating pH Ex. 5) A solution contains 3.5 x 10-5 M of H+ ions, what is the pH of the solution? Formula: pH= -log [H+] pH= -log ( 3.5 x 10-5) In calculator pH= -log ( 3.5 E -5) pH = 4.46 =

Calculating pH Ex. 5) A solution contains 3.5 x 10-5 M of H+ ions, what is the pH of the solution? Formula: pH= -log [H+] pH= -log ( 3.5 x 10-5) In calculator pH= -log ( 3.5 E -5) pH = 4.46 = acid

pH and Water Water is amphoteric; it can act as both an acid and a base in an aqueous solution. Water contains an equal number of H+ and OH- ions. H2O H+ + OH-

Ion Product Constant of Water Kw is the ion product constant for water. Represents the equilibrium for the self ionization of water. Formula: Kw = [H+][ OH-]

Ex. 6) What is the Kw if [H+] = 1.0 x 10-7 and [ OH-]= 1.0 x 10-7?

Ex. 6) What is the Kw if [H+] = 1.0 x 10-7 and [ OH-]= 1.0 x 10-7? Kw = [H+][ OH-]

Ex. 6) What is the Kw if [H+] = 1.0 x 10-7 and [ OH-]= 1.0 x 10-7? Kw = [H+][ OH-] Kw= (1.0 x 10-7) x (1.0 x 10-7)

Ex. 6) What is the Kw if [H+] = 1.0 x 10-7 and [ OH-]= 1.0 x 10-7? Kw= (1.0 x 10-7) x (1.0 x 10-7) Kw= 1.0 x 10-14

Ex. 6) What is the Kw if [H+] = 1.0 x 10-7 and [ OH-]= 1.0 x 10-7? Kw= (1.0 x 10-7) x (1.0 x 10-7) Kw= 1.0 x 10-14 This is a constant! Kw always equals 1.0 x 10-14

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral?

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? Kw= [H+][OH-]

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? Kw= [H+][OH-] 1.0 x 10-14 = [H+][ 2.4 x 10-4]

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? Kw= [H+][OH-] 1.0 x 10-14 = [H+][ 2.4 x 10-4] [H+] = 1.0 x 10-14/ 2.4 x 10-4

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? Kw= [H+][OH-] 1.0 x 10-14 = [H+][ 2.4 x 10-4] [H+] = 1.0 x 10-14/ 2.4 x 10-4 [H+] = 4.2 x 10-11 M

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? [H+] = 4.2 x 10-11 pH = -log(4.2 x 10-11) = 10.38 = Basic solution

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? [H+] vs [OH-] 4.2 x 10-11M vs 2.4 x 10-4 M

Ex. 7) The OH- concentration of an unknown solution is 2. 4 x 10-4 Ex. 7) The OH- concentration of an unknown solution is 2.4 x 10-4. What is the H+ concentration of the solution? Is the unknown solution acidic, basic, or neutral? [H+] vs [OH-] 4.2 x 10-11M vs 2.4 x 10-4 M [OH-] is larger so the solution is Basic

Finding [H3O+] You can use pH to find the [H3O+] [H3O+] = 10^-pH OR [H+] = 10^-pH Ex. 8) Find [H3O+] if pH = 4.720

Finding [H3O+] Ex. 8) Find [H3O+] if pH = 4.720 [H3O+] = 10^-pH [H3O+] = 10^-4.720

Finding [H3O+] Ex. 8) Find [H3O+] if pH = 4.720 [H3O+] = 10^-pH [H3O+] = 10^-4.720 [H3O+] = 1.91 x 10-5 M

Solving for OH- You can also substitute OH- in the place of H3O+. pOH = -log[OH-] or [OH-] = 10^-pOH Ex. 9) Find the pOH when [OH-] = 2.700 x 10-8M

Solving for OH- Ex. 9) Find the pOH when [OH-] = 2.700 x 10-8M pOH = -log[OH-] pOH = -log (2.700 x 10-8)

Solving for OH- Ex. 9) Find the pOH when [OH-] = 2.700 x 10-8M pOH = -log[OH-] pOH = -log (2.700 x 10-8) pOH = 7.5686

Ex. 10) Find [OH-] if pOH = 5.77

Ex. 10) Find [OH-] if pOH = 5.77 [OH-] = 10^-pOH [OH-] = 10^-5.77

Ex. 10) Find [OH-] if pOH = 5.77 [OH-] = 10^-pOH [OH-] = 10^-5.77 [OH-] = 1.7 x 10-6 M

Formulas To find either pH or pOH when given the other one pH + pOH = 14 To find pH given hydrogen ion concentration pH= -log [H+] (or pH= -log [H3O+]) To find hydrogen ion or hydroxide ion concentration when given the other one Kw = [H+][ OH-] Kw= 1.0 x 10-14 To find hydrogen ion concentration when given pH [H3O+] = 10^-pH To find pOH when given hydroxide concentration pOH = -log[OH-] To find hydroxide ion concentration when given pOH [OH-] = 10^-pOH

Using Google, Define and give examples Acids: Bases:

Acid Base Reactions HA + BOH → HOH + B+A- Acid + Base = neutralization reaction Acid + Base → water + salt (usually) Salt = (+) ion from base & (-) ion from acid Positive ions are always listed first

Arrhenius Swedish Chemist Svante Arrhenius created a model for acids and bases in 1883. acids are anything that generate H+ in aqueous solutions, while bases produce OH- in aqueous solutions

Arrhenius Model- Acid H+ (aq) + Cl- (aq) HCl (g) Acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution.

Arrhenius Model- Base NaOH (s) Na+(aq) + OH- (aq) Base is a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in aqueous solution. NaOH (s) Na+(aq) + OH- (aq)

Bronsted- Lowry Model Danish chemist Bronsted and English chemist Lowry proposed a model that focuses on the Hydrogen Ion An Acid is a hydrogen-ion donor A Base is a hydrogen-ion acceptor

Bronsted-Lowry Acid-Base Theory weak acids have strong conjugate bases weak bases have strong conjugate acids primary reason they are weak acids or bases: strong conjugates recombine to form the original species Water can be either an acid or base in Bronsted-Lowry theory It is both amphiprotic and amphoteric amphiprotic ~ can donate or accept a proton amphoteric ~ a substance that can be either an acid or a base. 12 13

Ionization The Bronsted-Lowry Model also shows if and acid or base is strong based on ionization. Strong acid- completely ionized Weak acid- partial ionization aqueous solutions of strong acids, weak acids, strong bases, and weak bases conduct electricity

Differences between Arrhenius & Bronsted-Lowry theories Reaction does not have to occur in an aqueous solution bases do not have to be hydroxides ~ ammonia is not a hydroxide

Strength and Concentration Strength – how completely it ionizes Strong – ionizes completely or almost completely Weak – ionizes partly Concentration Concentrated - a lot of acid/base in water. Dilute – a little acid/base in water.

12 M HCl is a strong acid with a high concentration Adding 6L of water to this solution would do what to the solution: strong acid, dilute solution Vinegar has acetic acid, which is weak, in low concentration = dilute 12 M acetic acid would still be weak, because it only partially ionizes, but it would be a concentrated solution, because there is a lot of acid dissolved in a little water.

List of Strong Acids and Bases strong acids - ionize 100% in water HCl, HBr, HI, H2SO4, HNO3, HClO4, HClO3 strong bases - ionize 100% in water LiOH, NaOH, KOH, RbOH, CsOH, (all Group 1A) Ca(OH)2, Sr(OH)2, Ba(OH)2, Ra(OH)2 (some from Group 2A)

Strong Acids Since strong acids are completely ionized they produce the maximum number of ions. Strong acids are good conductors Reaction only moves in one direction, represented with an arrow in one direction.

HCl H+ + Cl- HBr H+ + Br – H2SO4 H+ + HSO4 -

Weak Acids An acid that ionizes partially in dilute aqueous solutions Produce fewer ions, so they are poor conductors Reactions move both directions until equilibrium is reached, represented by an arrow in both directions

HF H+ + F- H2S H+ + HS- H2CO3 H+ + HCO3-

Conjugate Acid Conjugate Base The species produced when a base accepts a hydrogen ion to form an acid Conjugate Base The species that results when an acid donates a hydrogen ion to form a base.

Conjugate acid – base pairs 2 compounds with the same chemical formula, but the acid of the pair will have 1 more H NH3 & NH4 + H2SO4 & HSO4- H2O & H3O+

NH3 + H2O NH4+ + OH- Bronsted-Lowry Model Conjugate aCID aCID bASE

Identify the acid, base, conj. acid & conj. base. Ex. 11) HNO3 + H2O  NO3- + H3O+ Ex. 12) NH3 + HBr ↔ Br - + NH4+

Identify the acid, base, conj. acid & conj. base. Ex. 11) HNO3 + H2O  NO3- + H3O+ Acid Base CB CA Ex. 12) NH3 + HBr ↔ Br - + NH4+

Identify the Acid, Base, Conj. Acid & Conj. Base Ex. 11) HNO3 + H2O  NO3- + H3O+ Acid Base CB CA Ex. 12) NH3 + HBr ↔ Br - + NH4+ Base Acid CB CA

Titration Use known solution (standard solution) to find the concentration of an unknown solution Drop by drop process Endpoint – point of color change of indicator When neutralized Equivalence point: where the 2 solutions in a titration are present in chemically equivalent amounts

Think back to the Indicator lab…which one would you consider the best indictor of acids and bases?

Universal Indicator Changes colors at almost every pH!

Steps to solving titration problems 1st Write a balanced equation 2nd Write down all given information, including what you are looking for 3rd Plug data into the Titration equation and then solve for the unknown MAVA = MBVB nA nB M = Molarity V= Volume n = number of moles from the mole ratios in the balanced equation. A = acid B = base

Ex. 13) In a titration, 0.0274 L of 0.0154 M barium hydroxide is added to 0.0200 L of hydrochloric acid. What is the molarity of the acid? Ex. 14) By titration, a 0.0128M sulfuric acid solution is neutralized by 27.4 mL of 0.0165 M lithium hydroxide solution. What volume of sulfuric acid did you begin with?

Buffers Resist changes or swings in pH Blood pH approx 7.4 Fatal if fall or rise more than 0.3 pH units Buffers in your blood prevent big changes when, for example, you eat a orange (citric acid)

Precipitate Reactions When two compounds come together to form an aqueous compound and a solid compound. (Double replacement rxns) 2NaOH(aq) +CuCl2(aq) 2NaCl(aq) +Cu(OH)2(s) KI(aq) + AgNO3(aq)KNO3(aq) + AgI(s) Use your dissociation table to check solubility If insoluble – compound will precipitate or settle out of solution as a solid

Oxidation-Reduction Reaction A reaction in which electrons are transferred from one atom to another (All single replacement, combustion, synthesis, and decomposition rxns) 2KBr(aq) + Cl2(aq)  2KCl(aq) + Br2(aq) The chlorine on the left steals electrons from the bromine in KBr to become KCl and Br2 on the right.

Oxidation- Reductions Reaction

Remember Acid-Base Reaction Form SALT + WATER (Double replacement rxns) Mg(OH)2 + 2HCl  MgCl2 + H20 base + acid  salt + water Salt = any ionic compound made up of a cation (+) from a base and an anion (-) from an acid

Identify the following reaction: as 1) precipitation, 2) oxidation-reduction, or 3)acid-base 2K + Br2  2KBr H3N + 3CsOH  Cs3N + 3H2O MgCl2 + Li2CO3  MgCO3 + 2LiCl Look on dissociation table to see if either compound is insoluble

Identify the following reaction: as 1) precipitation, 2) oxidation-reduction, or 3)acid-base 2K + Br2  2KBr (oxidation-reduction) H3N + 3CsOH  Cs3N + 3H2O (acid-base) MgCl2 + Li2CO3  MgCO3 (s)+ 2LiCl(aq) (Precipitation) Look on dissociation table to see if either compound is insoluble