Acids and Bases

BELL WORK *Obtain ipad from cart corresponding to seat number answer survey question! PollEv.com/michellemart898

How many foods can you think of that are sour? sour milk – lactic acid vinegar – acetic acid carbonated beverages – phosphoric acid lemons – citric acid apples – malic acid Chances are almost all the foods you thought of owe their sour taste to an acid!

Question? Who has heard of someone using an antacid for an upset stomach? What does this indicate about the contents of our stomach? Answer! Our stomachs contain acid. Medical antacid preparations typically contain weak bases to counteract high levels of acids.

H. pylori Barry Marshall Nobel Prize 2005

Objectives List general properties of aqueous acids and bases. Name common binary acids and oxyacids. Explain the difference between strong and weak acids and bases.

Acids Characteristics: sour taste change color of acid-base indicators react with bases to produce salts and waters Acids were 1st recognized as a distinct class of compounds bc of their common properties of their aqueous solutions

Acids Conduct Electric Current Acids Characteristics: Acids Conduct Electric Current Acids dissolve in water break into ions Ions in solution conduct an electric current Example: Sulfuric acid in car battery conducts electricity to start car’s engine

Acids Characteristics: some acids react with active metals and release hydrogen gas

Acid Nomenclature *binary acid- contains only 2 different elements= H + EN element *oxyacid- compound of H,O, and a 3rd element, usually a nonmetal

Name the following acids: 1. HBr Hydrobromic acid 2. HNO3 nitric acid 3. H2SO3 sulfurous acid

Base Characteristics: bitter taste in aqueous solutions corrosive/contact skin can result in severe burns conduct electric current change color of acid-base indicators dilute solutions feel slippery react with acids to produce salts and water

Common Bases Found in cleaning products Ammonia is in cleaners and fertilizer Sodium hydroxide is used to make soap (lye) Milk of magnesia and antacids

Svante Arrenhius Swedish chemist 1859-1927 Understood that aqueous solutions of acids and bases conducted an electric current Theorized that acids and bases must produce certain ions in solution…

Arrhenius Acids def. a chemical compound that will increase the concentration of H+ ions in aqueous solutions HCl  H+ + Cl-

Acids in Water H+ that separates from the acid and forms with a water molecule H2O to form hydronium ions H3O+

Arrhenius Base substance that will increase the concentration of hydroxide ions (OH-) in water ex: NaOH NaOH(s) + H20(l) Na+(aq) + OH-(aq) + H2O(l)

Ammonia, NH3 Base that does not contain an –OH In water, ammonia attracts an H+ which leaves an OH-. household cleaner that should not be mixed with other cleaners that contain chlorine (bleach etc) bc produces toxic gases that can damage to lungs or even death

Strong Acids and Bases Strong completely ionizes in aqueous solutions Weak partially ionizes

Relationship of [H3O+] to [OH–] Section 1 Properties of Acids and Bases Chapter 14 Relationship of [H3O+] to [OH–]

HOMEWORK Section Review pg 476 #1-5

Bell Work Read the Cross-Disciplinary Connection entitled “Acid Water-A Hidden Menace” on page 477. Answer the three questions at the end of the article.

List 3 terms that describe this person…

Section 2 Acid-Base Theories Chapter 14 Objectives Define and recognize Brønsted-Lowry acids and bases. Define a Lewis acid and a Lewis base. Name compounds that are acids under the Lewis definition but are not acids under the Brønsted-Lowry definition.

Brønsted-Lowry Acids and Bases Section 2 Acid-Base Theories Chapter 14 Brønsted-Lowry Acids and Bases A Brønsted-Lowry acid is a molecule or ion that is a proton donor. Hydrogen chloride acts as a Brønsted-Lowry acid when it reacts with ammonia. Water can act as a Brønsted-Lowry acid.

Brønsted-Lowry Acids and Bases, continued Section 2 Acid-Base Theories Chapter 14 Brønsted-Lowry Acids and Bases, continued A Brønsted-Lowry base is a molecule or ion that is a proton acceptor. Ammonia accepts a proton from the hydrochloric acid. It acts as a Brønsted-Lowry base. The OH− ion produced in solution by Arrhenius hydroxide bases (NaOH) is the Brønsted-Lowry base. The OH− ion can accept a proton

Brønsted-Lowry Acids and Bases, continued Section 2 Acid-Base Theories Chapter 14 Brønsted-Lowry Acids and Bases, continued In a Brønsted-Lowry acid-base reaction, protons are transferred from one reactant (the acid) to another (the base). acid base

Monoprotic and Polyprotic Acids Section 2 Acid-Base Theories Monoprotic and Polyprotic Acids A monoprotic acid is an acid that can donate only one proton (hydrogen ion) per molecule. HClO4, HCl, HNO3 only one ionization step

Monoprotic and Polyprotic Acids, continued Section 2 Acid-Base Theories Chapter 14 Monoprotic and Polyprotic Acids, continued A polyprotic acid is an acid that can donate more than one proton per molecule. H2SO4, H3PO4 Multiple ionization steps (1) (2) Sulfuric acid solutions contain H3O+, ions

Monoprotic and Polyprotic Acids, continued Section 2 Acid-Base Theories Chapter 14 Monoprotic and Polyprotic Acids, continued A diprotic acid is the type of polyprotic acid that can donate two protons per molecule H2SO4 A triprotic acid is the type of polyprotic acid that can donate three protons per molecule. H3PO4

Chapter 14 Lewis Acids and Bases Section 2 Acid-Base Theories Chapter 14 Lewis Acids and Bases A Lewis acid is an atom, ion, or molecule that accepts an electron pair to form a covalent bond. The Lewis definition is the broadest of the three acid definitions. A bare proton (hydrogen ion) is a Lewis acid

Lewis Acids and Bases, continued Section 2 Acid-Base Theories Chapter 14 Lewis Acids and Bases, continued The formula for a Lewis acid need not include hydrogen. The silver ion can be a Lewis acid Any compound in which the central atom has three valence electrons and forms three covalent bonds can react as a Lewis acid.

HOMEWORK pg 482 #1-3 answer on same page as section 1 http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Acids_and_Bases/Acid/Arrhenius_Concept_of_Acids_and_Bases http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Acids_and_Bases/Acid/Bronsted_Concept_of_Acids_and_Bases http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Acids_and_Bases/Acid/Lewis_Concept_of_Acids_and_Bases HOMEWORK pg 482 #1-3 answer on same page as section 1

Section 3 Acid-Base Reactions Chapter 14 Objectives Describe a conjugate acid, a conjugate base, and an amphoteric compound. Explain the process of neutralization. Define acid rain, give examples of compounds that can cause acid rain, and describe effects of acid rain.

Conjugate Acids and Bases Section 3 Acid-Base Reactions Chapter 14 Conjugate Acids and Bases The species that remains after a Brønsted-Lowry acid has given up a proton is the conjugate base of that acid. acid conjugate base

Conjugate Acids and Bases, continued Section 3 Acid-Base Reactions Chapter 14 Conjugate Acids and Bases, continued Brønsted-Lowry acid-base reactions involve two acid-base pairs, known a conjugate acid-base pairs. acid1 base2 base1 acid2

Conjugate Acids and Bases, continued Section 3 Acid-Base Reactions Chapter 14 Conjugate Acids and Bases, continued Strength of Conjugate Acids and Bases The stronger an acid is, the weaker its conjugate base The stronger a base is, the weaker its conjugate acid strong acid base acid weak base

Conjugate Acids and Bases, continued Section 3 Acid-Base Reactions Chapter 14 Conjugate Acids and Bases, continued Strength of Conjugate Acids and Bases, continued Proton transfer reactions favor the production of the weaker acid and the weaker base. stronger acid stronger base weaker acid weaker base The reaction to the right is more favorable weaker acid weaker base stronger acid stronger base The reaction to the left is more favorable

Relative Strengths of Acids and Bases Section 3 Acid-Base Reactions Chapter 14 Relative Strengths of Acids and Bases Relative Strengths of Acids and Bases

Chapter 14 Amphoteric Compounds Section 3 Acid-Base Reactions Chapter 14 Amphoteric Compounds Any species that can react as either an acid or a base is described as amphoteric. example: water water can act as a base acid1 base2 acid2 base1 water can act as an acid base1 acid2 acid1 base2

Amphoteric Compounds, continued Section 3 Acid-Base Reactions Chapter 14 Amphoteric Compounds, continued –OH in a Molecule The covalently bonded OH group in an acid is referred to as a hydroxyl group. Molecular compounds containing —OH groups can be acidic or amphoteric. The behavior of a compound is affected by the number of oxygen atoms bonded to the atom connected to the —OH group.

Section 3 Acid-Base Reactions Chapter 14 Oxyacids of Chlorine

Neutralization Reactions Chapter 14 Neutralization Reactions Strong Acid-Strong Base Neutralization In aqueous solutions, neutralization is the reaction of hydronium ions and hydroxide ions to form water molecules. A salt is an ionic compound composed of a cation from a base and an anion from an acid.

Neutralization Reactions Section 3 Acid-Base Reactions Chapter 14 Neutralization Reactions

Chapter 14 Acid Rain NO, NO2, CO2, SO2, and SO3 gases from industrial processes can dissolve in atmospheric water to produce acidic solutions. example: Very acidic rain is known as acid rain. Acid rain can erode statues and affect ecosystems.

Modern Chemistry Chapter 15 Acid-Base pH

Draw the chemical formula of a hydroxide ion and a hydronium ion:

Self-ionization of water occurs when two water molecules produce a hydronium (H3O+) and a hydroxide (OH-) ion

Concentration (moles per liter) = [ ] In water at 25°C: [H3O+] = 1.0 x 10-7 M [OH-] = 1.0 x 10-7 M The mathematical product of [H3O+] and [OH-] remains constant in water and dilute aqueous solution at constant temperature. The ionization constant (Kw) of water is: Kw = [H3O+] [OH-] = 1.0 x 10-14 M

Acidic, Basic, & Neutral IF [H3O+] > [OH-] then solution is acidic. IF [H3O+] < [OH-] then solution is basic. IF [H3O+] = [OH-] then solution is neutral.

Calculating [H3O+] & [OH-] Since the product of the hydronium and hydroxide ion concentrations is a constant, we can use the following formula to determine these concentrations. [H3O+] [OH-] = 1.0 x 10-14 M

Practice Problems Determine the hydronium and hydroxide ion concentration in a solution that is 1.0 x10-4 M HCl.

Determine the hydronium and hydroxide ion concentration in a solution that is 1.0 x10-3 M HNO3.

Determine the hydronium and hydroxide ion concentration in a solution that is 3.0 x10-2 M NaOH.

The pH Scale pH- hydrogen power The pH of a solution is defined as the negative of the common logarithm of the hydronium ion concentration, [H3O+]. pH = -log [H3O+] pH = -log [1 x 10-7] = 7.0

The pOH of a solution is defined as the negative of the common logarithm of the hydroxide ion concentration, [OH-]. pOH = -log [OH-] pOH = -log [1x10-7] = 7.0

pH & pOH pH + pOH = 14 14 – pH = pOH 14 – pOH = pH

Determine the pH of the following solutions: a. 1 x 10-3 M HCl b. 1.0 x 10-5 M HNO3 c. 1 x 10-4 M NaOH d. 1.0 x 10-2 M KOH

Calculating pH What is the pH of a solution if the [H30+] is 6.7 x 10-4 M? What is the pH of a solution if the [H30+] is 2.5 x 10-2 M? What is the pH of a 2.5 x 10-6 M HNO3 solution? What is the pH of a 2.0 x 10-2 M Sr(OH)2 solution?

Calculate Concentration from pH The pH of a solution is determined to be 5.0. What is the hydronium ion concentration of this solution? The pH of a solution is determined to be 12.0. What is the hydronium ion concentration of this solution?

Indicator An organic compound that changes color in acid or base Examples: litmus - red/blue phenolphthalein - colorless/pink red cabbage juice - pink/green Acid  blue indicator litmus paper turns red in the presence of acid Base red indicator litmus paper turns blue in the presence of base