Acids and Bases

Acid Definition: aqueous solution of Hydrogen containing compounds Name the following: HCl H2SO4 H2SO3 H2S Remember: H with an element: hydro_______ic acid H with polyatomic ion ending with –ate: _______ic acid H with polyatomic ion ending with –ite: _______ous acid

Acid Definition: aqueous solution of Hydrogen containing compounds Name the following: HCl hydrochloric acid H2SO4 sulfuric acid H2SO3 sulfurous acid H2S hydrosulfuric acid

Base Many contain the polyatomic ion OH- (hydroxide) Name the following bases: NaOH Ca(OH)2 Cu(OH)2 NH4OH Follow ionic naming rules: name metal, name nonmetal, do NOT use prefixes! If the metal is a transition metal, use roman numeral for its charge

Base Definition (for now): Contains the polyatomic ion OH-1 (hydroxide) Name the following bases: NaOH sodium hydroxide Ca(OH)2 calcium hydroxide Cu(OH)2 copper (II) hydroxide NH4OH ammonium hydroxide

Properties of Acids Ionize in water  H3O+ Corrosive to metals and skin. (React with most metals to form hydrogen gas.) Taste sour (like lemons) Frequently feel "sticky" pH less than 7. Neutralizes bases producing salt and water. Electrolytes.

Properties of Bases Ionize in water  OH- Feel "slippery". Taste bitter (like soap) Electrolytes pH greater than 7. Neutralizes acids producing a salt and water

Indicators Indicators are added to chemicals to determine the pH. They change colors in different pH’s. You need to memorize the indicators and colors!

Acid Base Indicators Type Acid Neutral Base Red Litmus Red Blue Blue Litmus Phenolphthalein Clear Hot pink Bromothymol Blue Yellow Green

Uses of Common Acids H2SO4 : Car batteries HNO3 : Used to make rubber, plastics, and pharmaceuticals H3PO4 : Flavoring agent in beverages (soda) HCl : Stomach acid CH3COOH: Vinegar

Uses of Common Bases Mg(OH)2 : antacids, milk of magnesia NaOH : Cleaners (e.g. drain cleaners) Ca(OH)2 : slaked lime (used in mortars, plasters, and cements)

Acids and Bases are electrolytes! Why are acids and bases electrolytes? Because they ionize in water to form ions, therefore allowing them to conduct electricity when dissolved!

Ionization equation for HBr: Ionization equation for NH3:

Ionization equation for HBr: HBr + H2O  H3O+ + Br - (H3O+ is called the hydronium ion and is many times used interchangeably with H+) Ionization equation for NH3: NH3 + H2O  NH4+ + OH -

Strength vs. Concentration Concentration: amount of acid or base ÷ amount of water or solution (MOLARITY: mol/L) Strength: how well that particular acid or base ionizes (partially or completely into H+ or OH-) Strong acid/base: an acid/base that ionizes almost completely Weak acid/base: an acid/base that only slightly ionizes

List of Strong and Weak acids HCl H2SO4 HF H2SO3 HBr HClO3 H2S H3PO4 HI HClO4 HNO2 HNO3 Organic acids: end in –COOH, weak acid Ex: vinegar  CH3COOH

List of Strong and Weak Bases Strong bases completely dissociates and are strong electrolytes Weak bases only dissociate partially and are weak electrolytes Strong Weak Group I and II metals with hydroxides NH3 and any non-group I or II hydroxide

KOH – Strong Base KOH(s)K+(aq) + OH-(aq) Cu(OH)2 – Weak Base Cu(OH)2(aq)↔ Cu2+(aq) + 2OH-(aq)

Strong vs. Weak Strong acids or bases with completely ionize when dissolved in water. The ionization equation will have  arrow. Weak acids or bases only partially dissociate and the dissociation equations for weak bases are always reversible .

Acid and Base Theories Theory Acid Definition Base Definition Arrhenius Releases H+ into solution Releases OH-into solution Bronsted-Lowery Proton (H+) donor Proton (H+) acceptor

What happens when you mix an Arrhenius acid with an Arrhenius base? Neutralization, producing a salt and water General neutralization reaction: Salt: Ionic compound from the cation of a base and the anion of an acid

Complete and net ionic equations! LiOH(aq) + HBr(aq)  LiBr(aq) + H2O(l)

Complete and net ionic equations! ANSWER! LiOH(aq) + HBr(aq)  LiBr(aq) + H2O(l) Complete Li+(aq) + OH –(aq) + H+(aq) + Br –(aq)  Li+(aq) + Br –(aq) + H2O(l) Net OH –(aq) + H+(aq)  H2O(l)

Name the salt produced and write the balanced reaction: Sodium hydroxide and hydrochloric acid Calcium hydroxide and sulfuric acid Potassium hydroxide and nitric acid

Name the salt produced and write the balanced reaction: Answers! Sodium hydroxide and hydrochloric acid NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l) salt: sodium chloride, NaCl Calcium hydroxide and sulfuric acid Ca(OH)2(aq) + H2SO4(aq)  CaSO4(aq) + 2H2O(l) salt: calcium sulfate, CaSO4 Potassium hydroxide and nitric acid KOH(aq) + HNO3(aq)  KNO3(aq) + H2O(l) salt: potassium nitrate, KNO3

Bronsted-Lowery Acid and Base HCl + NH3  NH4+ + Cl- H2O(l) + NH3(aq) ↔ NH4+(aq) + OH-(aq)

Bronsted-Lowery Acid and Base HCl + NH3  NH4+ + Cl- acid base H2O(l) + NH3(aq) ↔ NH4+(aq) + OH-(aq) acid base

Definitions Monoprotic acid: only has one ionizable hydrogen ex: HCl, HBr, HC2H3O2, HNO3 Polyprotic acid: more than one ionizable hydrogen ex: H2SO4, H3PO4 Amphoteric: substance that can act as an acid or as a base ex: H2O

Water as an acid or base Base H2SO4(aq) + H2O(l)  H3O+(aq) + HSO4-(aq) Acid NH3(aq) + H2O(l) ↔ NH4+(aq) + OH-(aq)

B-L Conjugate Acids and Bases Conjugate acid: The species that is formed when a B-L (Bronsted-Lowery) base gains a proton Conjugate base: The species that remains after a B-L acid has given up a proton

Identify the Conjugates NH3 + H3O+  NH4+ + H2O CH3OH + NH2-  CH3O- + NH3

Try these! OH- + H3O+  H2O + H2O H2O + NH2-  OH- + NH3

Try these! OH- + H3O+  H2O + H2O base acid conj. conj. acid base H2O + NH2-  OH- + NH3 acid base conj conj base acid

Write the Conjugate Base H3O+ H2SO4 HCO3- HOCl NH4+

Write the Conjugate acid SO32- PO43- C2H3O2- H2BO3-

Strength of conjugates The stronger an acid is, the weaker its conjugate base; the stronger a base is, the weaker its conjugate acid.

Ionization of water Kw = [H3O+][OH -] = 1.oo x10-14 Pure water ionize slightly according to: The product of molar concentrations of the ions is equal to a constant Kw. Kw = [H3O+][OH -] = 1.oo x10-14 [ ] means “molar concentration” or molarity This formula is in your reference table!

Relationships In a neutral solution: In an acidic solution: In a basic solution: Basically this is saying there is more H3O+ in acidic solutions, more OH- in basic solutions. The concentrations of both are the same in neutral solutions

pH and pOH Neutral 0 7 14 Acid Base Neutral 0 7 14 Base Acid pH: negative log of [H3O+], measure of “acidity” pOH: negative log of [OH-], measure of “basicity” Neutral 0 7 14 Acid Base Neutral 0 7 14 Base Acid

pH and pOH A change in [H+] by a factor of 10 causes the pH to change by 1. Solution with a pH of 6 has 10x the [H+] as a solution with a pH of 7. Solution with a pH of 3 has 1000x the [H+] as a solution with a pH of 6. What is the [H+] difference between pH of 1 and pH of 4? 4-1= 3  that’s how many zero’s Answer= pH 1 has 1000x more

Important formulas 1 4 2 5 3 6

Find the pH of the following: [H3O+] = 1.00 x 10-3M [H3O+] = 6.59 x 10-10M   [H3O+] = 7.01 x 10-6M

Find the [H3O+1] pH = 3   pH = 6.61 pH = 2.52

Find the pH for the following: pOH = 2   pOH = 1.26 pOH = 4.98

Find the pH for the following: [OH-] = 1.00 x 10-11M   [OH-] = 2.64 x 10-13M [OH-] = 3.45 x 10-8M

[OH-] = 1.00 x 10-6M [OH-] = 4.97 x 10-10M [OH-] = 2.93 x 10-2M Find the [H3O+1] [OH-] = 1.00 x 10-6M   [OH-] = 4.97 x 10-10M [OH-] = 2.93 x 10-2M

Find the ph 0.054M HCl 0.178M NaOH 0.033M H2SO4

pH continued Find the pH of the following: 3.0 M HF (8.1% dissociation)

pH continued Find the pH of the following: 3.0 M HF (8.1% dissociation) 3.0M(0.081) = 0.24M  [H+] pH = -log(0.24) = 0.62

Buffered Solution A solution that can resist changes in pH Made up of a weak acid and its conjugate base

Titrations An acid-base titration is a neutralization reaction that is performed in the lab in order to determine an unknown concentration of acid or base. The reaction is complete at the equivalence point.

Titrations Endpoint: When the indicator changes color; when you stop the titration Equivalence point: When the reaction is complete. All the acid and base have reacted to form salt and water. Not always a pH of 7!

Titration terms Indicator: weak acid or base; whose color changes in different pH’s (because the conjugate base/acid is a different color) Standard solution: solution of known concentration used as the titrant

Titration Curves On the following slide you will see 3 different curves. The relationships are: Strong Acid titrated with Strong Base Weak Acid titrated with Strong Base Strong Acid titrated with Weak Base Using those graphs compare the pH values of each substance as well as the equivalence points

More Titration Curves Strong acid and weak base curve Strong base and weak acid curve Strong acid and strong base curve

Diprotic Acid Curve

Try it! 1) If it takes 54mL of 0.1M NaOH to neutralize 125mL of an HCl solution, what is the concentration of the HCl? 2) What is the molar concentration of a 50.0mL solution of NaOH that is titrated to an endpoint with 15.0mL of a 0.00300M solution of H2SO4?

Test Topics Acid/Base Properties Naming Acids and Bases Electrolytes Strength vs. Concentration Memorize Strong/Weak Acids and Bases! Arrhenius and Bronsted-Lowry acids/bases Conjugate acids and bases Indicators (memorize colors) Neutralization Reactions pH, pOH, [H+], and [OH-] calculations Titration concepts, calculations, and curves Common uses of acids and bases ALL vocab Solutions Stuff