Schedule

ScheduleAcids & Bases Schedule Team Tree

Today18.1 & 18.2

Identify acids & basesStrong Acids & BasesNaming

Wednesday18.3

Concentration (pH & pOH)Molarity

Double Lab18.4

NeutralizationBuffersTitration

Wednesday Review

Friday Quiz

Unilever’s Bread & Butter

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Researchers have found that suppression of vasopressin can cause males (voles, anyway) to abandon their love nest and seek new mates.

A delicious acid

ScheduleAcids & Bases Schedule for Lava Lovers

Tuesday (2/14)18.1 & 18.2

Identify acids & basesStrong Acids & BasesNaming

Wednesday (2/15)18.3

Concentration (pH & pOH)Molarity

Wednesday (2/22)18.4

NeutralizationBuffers

Friday Double Lab (2/23)18.4

Titration LabQuiz

Today’s Objective – 18.1 & 18.2

• To identify acids and bases using the Arrhenius, Brønsted-Lowry and Lewis models.

• To identify strong & weak acids and bases.• To name acids & bases.

• Tonight’s homework: – read section 18.3 & take notes– mini quiz tomorrow

Content: What is an Acid?• Arrhenius model: A species that contains

hydrogen and produces hydrogen ions in an aqueous (water) solution.

HX H+ + X-

–Real example:

HCl H+ + Cl-

Content: What is an Acid?• Brønsted-Lowry model: hydrogen ion donor.

Produce conjugate acids and bases

HX(aq) + H2O H3O+(aq) + X-(aq)

–Real example:

HF(aq) + H2O H3O+(aq) + F-(aq)

Content: conjugate acids and bases

• conjugate acid: the species produced when a base accepts a hydrogen ion.

• conjugate base: the species that results when an acid donates its hydrogen ion.

acid base conjugate acid

conjugate base

Content: What is a base?

• Arrhenius model: species that produces hydroxide ions in an aqueous solution.

MOH M+ + OH-

–Real examples:

NaOH Na+ + OH-

Content: What is a base?

• Bronsted-Lowry model: hydrogen ion acceptor.

NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

acidbase conjugate acid

conjugate base

Content: Water – both acid & base

H2O + H2O • Known as: amphoteric

• Complete the equations. In each, is water an acid or base?– HX + H2O

– NH3 + H2O

Summarize: Compare & Contrast3 words or less

Model Acid Definition Base Definition

Arrhenius

Brønsted-Lowry

Summarize: Make Connections

• What real world substances are classified as acids and bases?

• What ion is likely present in acids?

Today’s Objective – 18.2 & 18.3

• To classify strong acids and bases v. weak acids & bases.

• To explain pH and pOH.

• Tonight’s homework: – worksheet if you don’t finish it in class.

Content: Strong Acids and Bases

• Strong: completely ionizes in aqueous solutions

– Strong acid equation• HX (aq)

– Strong base equation• MOH

Strong Acids & BasesMemorize

Acids• HCl• HBr• HI• HNO3

• H2SO4

• HClO4

Bases• Hydroxides of group 1 or 2

metals– Ex: NaOH, KOH, Mg(OH)2

Content: Weak acids & bases

• Only partially dissociate in water. Reaction does not go to completion, is reversible.

• Use double arrow– Weak acid reaction

• HB (aq)

– Weak base reaction• NH3(aq) + H2O

What does this look like?

• http://phet.colorado.edu/en/simulation/acid-base-solutions

Check for Understanding

• Classify the following as weak/strong acid/base. – HF– LiOH– HBr– NaOH– NH3

Check for Understanding

• What would happen to the following substances in water? Write an equation for each and draw what this would look like– HF -LiOH

– NaOH -NH3

– HBr

Classification of acids and Bases

• If [H+] > [OH-] =• If [OH-] > [H+] =• If [H+] = [OH-] =

Today’s Objective• To understand pH.

• To neutralize an acid using titration.

18.3 Ion Product Constant for Water• Pure water contains equal concentrations of H+

and OH– ions.

• The ion production of water

Kw = [H+][OH–] = 1.0x10-14

• a number that doesn’t change, a constant number.

• equals the concentration of the H+ and OH– ions.

Ion Product Constant for Water• In an acidic or basic solution, as the [H+] goes up,

[OH-] goes down, and vice versa so Kw remains the same.

The pH scale• Scientific notation is cumbersome, so it’s re-expressed

using logs.

• pH is the negative logarithm of the hydrogen ion concentration of a solution.

pH = –log [H+]

Did she just say “log?!”

• 103 = 1000o 10 is the base. o 3 is the exponent.

• A logarithm is basically solving for exponents, x in the followingo 10x=1000o here x = 3

• log101000 = x

• log101000 = 3

• "The log of 1000, base 10, is 3”

logbase(number) = exponent

So for pH…

• If [H+] = 1.0 x 10-7

• and pH = - log [H+]

• then pH = - log [1.0 x 10-7] = - (-7) log 10

• and pH = 7 x 1 = 7

• so this would be a neutral solution.

The pOH scale• pOH is the negative logarithm of the hydroxide

ion concentration of a solution.

pH = –log [OH-]

pH + pOH = 14

Concentration of Strong Acids & Bases

For all strong monoprotic acids (ones that have one H+ ion to donate) the concentration of the acid is the concentration of H+ ions.

For all strong bases, the concentration of the OH– ions is the concentration of the base.

A 0.6M solution of NaOH means there are 0.6 moles of NaOH per liter of water.

NaOH Na+ + OH-

For every mole of NaOH, there is one mole of OH-, so the concentration is the same.

Neutralization

• What happens if we mix a strong acid and a strong base?

• A neutralization reaction is a reaction in which an acid and a base in an aqueous solution react to produce a salt and water.

• The net reaction (without the salt) is:

Titration

• It’s all in the technique…

Titration• Titration is a method for determining the concentration of

a solution by reacting a known volume of that solution with a solution of known concentration.

HCl + NaOH NaCl + H2O

• If I have 50 mL of a 0.5M solution of HCl, how much of a 0.5M solution of NaOH should be needed to neutralize it?

How can we use this to determine the concentration of an unknown acid or base?

Titration Procedure• In a titration procedure, a measured volume of an acid

or base of unknown concentration is placed in a beaker, and initial pH recorded.

Titration Procedure• A buret is filled with the titrating solution of known

concentration, called a titrant.

Titration Procedure• Measured volumes of the titrant are added slowly

and mixed into the solution in the beaker.

• The pH is read and recorded after each addition.

pH indicator solution• Chemical dyes whose color are affected by acidic and

basic solutions are called acid-base indicators.

• An end point is the point at which an indicator used in a titration changes color.

• An indicator will change color at the equivalence point.

End Point

• The process continues until the reaction reaches the equivalence point, which is the point at which moles of H+ ions from the acid equals moles of OH– ions from the base.

• An abrupt change in pH occurs at the equivalence point.

Expected Titration Curve

Let’s Practice

Naming Bases

• Bases– Group 1 and 2 hydroxides…– NH3 (ammonia)

Naming Acids

• Binary Acids (hydrogen + 1 element)– Prefix “Hydro” to name the hydrogen part of the

compound– The rest of the word consists of a form of the root

of the second element, plus the suffix “ic”– Second word is always “acid”

• Example: HCl Hydrochloric Acid• Example: HF Hydrofluoric Acid• Example: HI • Example: HBr

Naming Acids

• Oxyacids (contain hydrogen and oxyanion)– Identify oxyanion. The first word is the oxyanion

name and a suffix• If original suffix was “ate” “ic”• If original suffix was “ite” “ous”

– Second word = “acid”• Example: HClO4 = Perchloric Acid• Example: HClO3= Chloric Acid• Example: HClO2 =• Example: HClO= (adds chlorine to pools)• Example: HNO3

• Example: HNO2

In Conclusion

• Using the pH scale, identify what makes a substances acidic, basic or neutral

• What is more dangerous, an acid or a base?• What ion is responsible for an acidic solution?

A basic solution?• Name the following acids

• H2SO4

• H2SO3

• HCl• HF• H2CO3