Warm-Up: Acid Base Nomenclature Identify each compound as an acid or a base Provide the IUPAC name for each of the following: a) BaOH(aq) b) HF(aq) c) HClO4(aq) d) HCl(aq) e) KOH(aq) Provide the classical name for each of the following: a) HBr(aq) b) H2SO3(aq) c) H2S(aq) d) HClO4(aq)

Acids and Bases: Part I LG: I can describe the Arrhenius theory of acids and bases and what makes an acid strong or weak

Recall: Properties of Acids and Bases Property Acids Bases pH <7 >7 Taste Sour Bitter Feel Water-like Slippery Reaction with Metal Reacts No reaction Reaction with Indicators: Phenolphthalein Litmus Stays clear Turns Red Turns pink Turns Blue Acids react with metal if the metal is more reactive than hydrogen (metal can displace hydrogen from the acid compound)

Arrhenius Theory Svante Arrhenius was the first scientist to determine that electrolytic solutions contain dissociated ions Since acids and bases also conduct electricity, he concluded that they must also contain ions

Defining Acids and Bases Arrhenius bases – A substance that dissociates to produce hydroxide ions, OH-, when dissolved in water Ca(OH)2(s)  Ca2+(aq) + 2 OH-(aq) Arrhenius acid – a substance that ionizes to produce hydrogen ions, H+, when dissolved in water. HNO3(aq)  H+(aq) + NO3-(aq) Dissociation refers to the separation of positive and negative ions in an ionic compound Ionization means that ions form from uncharged molecules

Acid-Base Neutralization Arrhenius applied his theory of acids and bases to explain why the mixing of an acid with a base, produces a neutral solution: HCl(aq)  H+(aq) + Cl-(aq) NaOH(aq)  Na+(aq) + OH-(aq) Write total and net ionic equation showing the formation of water We will be looking at the the stoichiometry behind acid base neutralizations and how we can use neutralization to determine the concentration of n unknown acid or bases

Applications of Neutralization Reactions Acid wear on teeth Acids can solubilize basic compounds in tooth enamel Signs of wear: translucency, yellowing, sensitivity Acid reflux (“heartburn”) Stomach acid splashes up into esophagus Esophagus does not contain a protective mucus layer like the stomach

Strong and Weak Acids It is well known that vinegar is less dangerous than hydrochloric acid because vinegar has a higher pH; but what causes this difference? The answer is the degree to which an acid will ionize Vinegar: HC2H3O2(aq)  H+(aq) + C2H3O2-(aq) Hydrochloric Acid: HCl(aq)  H+(aq) + Cl-(aq) 1.3% Strong Acids Weak Acids Hydrochloric Acid, HCl Phosphoric Acid, H3PO4 Nitric Acid, HNO3 Ethanoic Acid, HC2H3O2 Sulfuric Acid, H2SO4 Carbonic Acid, H2CO3 Perchloric Acid, HClO4 Methanoic Acid, HCO2H >99% pH is a measure of the hydrogen ion concentration in a solution. The more molecules of an acid that ionize, the lower the pH will be.

Homework Pg. 469 #1, 4, 6, 7 Pg. 475 # 1, 3, 4, 6, 12

Acids and Bases II LG: I can describe the Bronsted-Lowry definitions of acids and bases and perform calculations relating hydrogen ion concentration and pH

Bronsted-Lowry Theory of Acids and Bases Arrhenius’ theory of acids and bases is limited by the inability to explain the basic properties of substances like ammonia (NH3), that do not contain hydroxide ions, OH- Johannes Bronsted and Thomas Lowry redefined acids and bases in broader terms: Acid – Hydrogen ion donor Base – Hydrogen ion acceptor

Conjugate Acids and Bases In the following example, which substance is the acid and which is the base? HCl(aq) + NH3(aq)  NH4+(aq) + Cl-(aq) A conjugate base is the product formed as the result of an acid losing a proton A conjugate acid is the product formed as the result of a base gaining a proton A conjugate base could theoretically regain the lost proton, thereby meeting the definition of a base A conjugate acid could re-release the proton it gained, thereby acting like an acid NH3 ad NH4+ are a conjugate acid-base pair (so are HCl and Cl-)

Strange Brew… Water is often referred to as being amphiprotic or amphoteric meaning that is can sometimes act as an acid and sometimes as a base. Acts like a base: H2SO4(aq) + H2O(l)  HSO4-(aq) + H3O+(aq) Acts like an acid: NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq) Yesterday when we talked about acids ionizing in water, we said that this increases the concentration of hydrogen ions in solution. In reality, hydrogen ions are very reactive and would be strongly attracted to the slight negative charge on the oxygen atoms of water, as a result, they form H3O + which is called a hydronium ion Identify conjugate acid-base pairs

pH pH or “Power of Hydrogen” is a scale which indicates the concentration of hydrogen ions in a solution The higher the concentration of hydrogen ions, the more acidic the solution will be. Each pH unit corresponds to a factor of 10 in the concentration How many times more acidic is a lemon compared to milk?

Calculating pH pH is defined as “the negative of the exponent to the base 10 of the hydrogen ion concentration” pH 7 Acidic > 1.0 x 10-7 mol/L > Basic (neutral) pH 9 = 1.0 x 10-9 mol/L pH 2 = 1.0 x 10-2 mol/L Try These… pH_____ = 1.0 x 10-5 mol/L Recall scientific notation: as the exponent gets smaller, the concentration of H+ is getting higher pH_____ = 6.2 x 10-4 mol/L pH_____ = 4.7 x 10-11mol/L

Calculating pH 𝐻 + = 10 −𝑝𝐻 𝑝𝐻=−𝑙𝑜𝑔 𝐻 + The following equation can be used to determine the hydrogen ion concentration for a given pH: 𝐻 + = 10 −𝑝𝐻 The following equation can be used to determine the pH for a given hydrogen ion concentration 𝑝𝐻=−𝑙𝑜𝑔 𝐻 + The above equations are the same, just rearranged to solve for different variables; an exponent with a base of 10 is the inverse operation of log

Practice The pH of a solution is 10.33. Determine the hydrogen ion concentration. 2) A solution has a hydrogen ion concentration of 4.7 x 10-11 mol/L. Determine the pH of the solution.

Homework Pg. 475 # 5, 7, 8, 10 + Handout to practice pH calculations