schedule acids & bases schedule team tree today 18.1 & 18.2 identify acids & bases...
TRANSCRIPT
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
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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