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½ sheet of paper and Chemistry book out
• About ¼-½ a page
• Use your own words to describe acids and bases. – Give examples of acids and bases.– What is pH?
– (Mr. B Note, do this as a class discussion. K of a KWL)
½ sheet of paper and Chemistry book out
• My example: Chicken bone in vinegar.
• Acids such as Pop absorb the calcium out of bones and make the bones weak and rubbery. That’s why pop is not sold in many schools.
• Can skip pH demo and go to slide 8.
Record this orderHCl, NaOH, H2SO4, HC2H3O2,
KOH, LiOH, HNO3
• Make observations when the phenolphthalein is added.
Record this orderHCl, NaOH, H2SO4, HC2H3O2,
KOH, LiOH, HNO3
• Make observations when the phenolphthalein is added.
• Predict what will happen when phenolphthalein is added to the last 2 solutions.
Record this orderHCl, NaOH, H2SO4, HC2H3O2,
KOH, LiOH, HNO3
• Make observations when the phenolphthalein is added.
• Predict - What will happen when phenolphthalein is added to the last 2 solutions?
• Predict – What will happen when a solid chunk of NaOH is added to water? HCl?
Record this orderHCl, NaOH, H2SO4, HC2H3O2,
KOH, LiOH, HNO3
• Explain, create a theory, about why some solutions turn pink.
Acids taste sour, become less acidic when mixed with bases.
Bases feel slippery and are bitter, become less basic when mixed
with acids.
What is the common name of a hydrogen ion?
What is the common name of a hydrogen ion?
What are the atomic parts of a hydrogen atom?
Hydrogen Ion?
What is the common name of a hydrogen ion?
What are the atomic parts of a hydrogen atom?
Proton and electron
Hydrogen Ion?Proton
What did you see at the start of all the acid formulas? (repeated next slide)
Arrhenius definition of:acid: generates [H+] in solution (HCl)
base: generates [OH-] in solution(NaOH)
Some textbooks call acids a Hydrogen donor instead of a proton donor.
HCl + H2O = H+ (aq) + Cl-(aq)NaOH(s) + H2O NaOH(aq)
NaOH(aq) = Na+(aq) + OH-(aq)
Arrhenius definition of:acid: generates [H+], Often Positive
base: generates [OH-] Often NegativeBut they are not always positive and
negative.Often but NOT ALWAYS!
For example,Sometimes they are neutral and have no charge. The can both be negative or positive, but the acid is always less
negative or the more positive.
Arrhenius definition of:acid: generates [H+], Often Positive
base: generates [OH-] Often Negative
So look at the signs and the one that is “more positive” is always the acid
because it has the [H+].
Common Bases. What do you notice common in their formulas?
Typical Acid Reaction in Water, H+ gets lonely and often combines with water.
Is water an acid or base?
So if acids begin with H and bases end with OH,What is the correct chemical formula for water?
Is water an acid or base? Both
So if acids begin with H and bases end with OH,What is the correct chemical formula for water? HOH (not H20)
Oldest or original definition:Copy the following into your powerpoint notes:
Acid Neutral Base (Water)pH 1 pH 7 pH 14 Strong Weak Weak Strong
Protons HydroxideH+ HOH OH-
H+ meet with OH- in the middle to form HOH
Bronsted-Lowry:acid: anything that donates a H+ ion
(proton donor)base: anything that accepts a H+ ion
(proton acceptor)Means a base does not have to have OH -
This definition is the most commonly used in industry.
HCl + Mg MgCl2 + H2Flashback: How do you balance this?
Lewis: acid= accept a pair of electrons
to form a covalent bondBase= e- donor
Acid with Covalent Bond: H : Cl H+ + Cl - = H:Cl H accepts e- from Cl
OH – as a base, donating an e- to H + H+ + OH - = H:OH
HCl + Mg MgCl2 + H2
Mg has formed a 2+ ion losing 2 electron H+ have each gained an electron forming H2
Remember all 3 definitions for the test:
Remember for test:When an acid and base react,
they producesalt and water
HCl + NaOH H+ + Cl- + Na+ + OH-
HCl + NaOH NaCl + HOH
Conjugate acid / Conjugate base pair:they are acid/base on the right or product side
of a reversible reaction(acid and base are reactants, Conjugates are
always Proton transfer, never OH).
Proton transfers .
acid+1 + base-
2 base-1 + acid+
2
acid+1 loses proton to become base-
1
base-2 gains proton to become acid+
2
. Proton transfers back
acid+1 + base-
2 base-1 + acid+
2
When the proton is returned, the process reverses or goes back the other direction.
Conjugate acid / Conjugate base pair:they are acid/base on the right or
product side of a reversible reaction(acid and base are reactants)
Ammonia plus water makes ammonium plus hydroxide
Note: any question that asks about conjugate means
Conjugate on the right
acid/base always means left side.
HOWEVER! If the word conjugate is NOT in the problem, then the acid or base may be on either side of the equation.
HCl (l) + H2O
(l) <--> H3O+(aq) + Cl -
(aq)
Label the acid/base and conjugate acid/base
HCl (l) + H2O
(l) <--> H3O+(aq) + Cl -
(aq)
Acid:_________
Base:_________
Conjugate Acid:_____________
Conjugate Base:_____________
Water reacts with the H+ in solution and forms the hydronium ion H3O+
Self-ionization of waterH2O ↔ H+ + OH-
New Concept:Water, acids, and bases have both
H+ and OH- in them at the same time.
It probably appeared that acid only has H+ but it actually has both of them. Bases also have
both.
Remember for test:All water contains all three
of the following:Water Molecules,
Hydronium ions, and Hydroxide Ions.
Hydronium Ion is H30+
Hydroxide Ion is OH-
Know ion formula and charge.
Important. REMEMBER THIS!
ion-product constant for water (Kw):
Where have we seen that 14 before?
Important. REMEMBER THIS!
ion-product constant for water (Kw):
[concentrations] :Brackets around a element
means concentration. What do we measure concentration in?
[concentrations] :are measured
In Molarity = moles/L of Solution
(remember: solute + solvent = solution)
acidic solution = [H+] is greater than [OH-]; but
solutions have both H+ and OH- in them
(and water molecules).
[H+] of an acidic solution is greater than
1 x 10-7M
NOTES: ACIDS: [H+] > 1 x 10-7M
How concentrated is the acid?The acidity is defined most typically by
the pH value,
pH= -log[H+]
(added my me)
pH is the exponent on the 10 (made positive).
pH 2 means 1.0 x 10-2 Molarity of [H+]
[H+] pH Example
Acids 1 X 100 0 HCl
1 x 10-1 1 Stomach acid
1 x 10-2 2 Lemon juice
1 x 10-3 3 Vinegar
1 x 10-4 4 Soda
1 x 10-5 5 Rainwater
1 x 10-6 6 Milk
Neutral 1 x 10-7 7 Pure water
Bases 1 x 10-8 8 Egg whites
1 x 10-9 9 Baking Soda
1 x 10-10 10 Tums® antacid
1 x 10-11 11 Ammonia
1 x 10-12 12 Mineral Lime - Ca(OH)2
1 x 10-13 13 Drano®
The pH scale is a measure of the concentration of H+ in solutionthe higher the H+ concentration
the lower the pH number
pH means probability of Hydrogen.
The pH scale is a measure of the concentration of H+ in solutionthe higher the H+ concentration
the lower the pH number
pOH?
pOH scale. Note that it is just the reverse of pH.Add pink line to your pH notes:
Acid Neutral Base (Water)pOH 14 pOH 7 pOH 1 Strong Weak Weak Strong
Protons HydroxideH+ HOH OH-
H+ meet with OH- in the middle to form HOH
Know these Equations for the test:pH + pOH = 14
pH= -log[H+]
pOH= -log[OH-]
10-pH = [H+]
10-pOH = [OH-](Discuss how to do on calculator. Point out the opposites. 2 and 4, 3 and 5.)
Examples of last slide, how to use calculator.
Given pH = 2.6, find pOH.Use pH + pOH = 14
Answer: 14 - 2.6 = 11.4
Given Molarity of H+ = [H+] = .0023 MFind pH. Use: pH= -log[H+]
Put in Calculator: -log[.0023] Answer: pH = 2.6 (2.638227)
Given pH = 2.6, find Molarity of H+ = [H+] Use10-pH = [H+]
Put in Calculator: 10-2.638227 Answer: .0023 or 2.3 x 10-3 M (or .0025)
(note: The bottom 2 equations or examples are opposites.)
Examples of last slide, how to use calculator.
Given [H+] = 2.3 x 10-3 Mfind pOH.
Put in Calculator: -log[.0023]
Gives pH = 2.6 Use pH + pOH = 14
Answer: 14 - 2.6 = 11.4 pOH = 11.4
[concentrations] ion-product constant for
water (Kw)
Important. REMEMBER THIS for
test!10 -14 / [H+] = [OH-] 10 -14 / [OH-] = [H+]
To change an acid to a base:Take away a H+ or add OH-
Take away a H+ Ex: HPO4 2- = PO4 3- + H+
Add OH- Ex: HCl + OH- = Cl- + HOH
Remember to balance charges! To change a base to an acid:
Add a H+ or take away an OH-
Ex: PO4 3- + H+ = HPO4 2-
For Conjugate Acids, take away H+
For Conjugate Bases, add H+ .
Remember to balance charges!
Monoprotic AcidDonates 1 H+
HCl = H+ + Cl-
Diprotic Acid Donates 2 H+
H2SO4 = 2H+ + SO4
2-
Triprotic Acid Donates 3 H+
H3PO4 = 3H+ + PO4
3-
Note: Number of H+ Donated may be different than the number of H. CH3COOH only donates 1 H+ and is Monoprotic.
If the [H+] in a solution is 1.0 x10-5 M, is the
solution acidic, basic, or neutral?
What is the [OH-] of this solution?
If the [H+] in a solution is 1.0 x10 -5 M, is the
solution acidic, basic, or neutral?
What is the [OH-] of this solution?
If the [H+] in a solution is 1.0 x10 -5 M, is the
solution acidic, basic, or neutral?
What is the [OH-] of this solution?
My way:Exp is 5 so pH is 5.14-5 = 9 = pOH
[OH-] =1.0 x10 -9 M
• A solution has a [H+] of 0.0023M what is the pH? What is the pOH.
• Does this solution contain more H+ or OH-?
• A solution has a [H+] of 0.0023M what is the pH? What is the pOH.
• Does this solution contain more H+ or OH-?
• A solution has a [H+] of 0.0023M what is the pH? What is the pOH.
• Does this solution contain more H+ or OH-?
• A solution has a [H+] of 0.0023M what is the pH? What is the pOH.
• Does this solution contain more H+ or OH-?
• (error due to rounding on calculator.)
• A solution has a [H+] of 0.0023M what is the pH? What is the pOH.
• Does this solution contain more H+ or OH-?
The pH is 4.7, what is the pOH, what is the [H+] (hydrogen ion
concentration)?
The pH is 4.7, what is the pOH, what is the [H+] (hydrogen ion
concentration)?O
You try it.The pOH is 6, what is the pH and
what is the [H+]?
The pOH is 6, what is the pH and what is the [H+]?
indicator (HIn) = a weak acid / base that undergoes dissociationin a known pH range
(changes colors).[H+] + [In-]
WOD: (HIn) Something that changes color to indicate a pH level.
Color Indicators
Acid dissociationconstant (Ka): is the ratio of the concentration of the dissociated (or ionized) form of an acid to
the concentration of the undissociated (nonionized) form.
Note: Dissolved Ions on top. Undissolved on bottom.
WOD in 2 slides.
Acid dissociationconstant (Ka):
HCl H+ + Cl-
The HCl and H+ + Cl- exist in the water at the same time.
Acid dissociationconstant (Ka): is the ratio of the
molarity of the ions over the molarity of the whole acid. High
number means strong acid.For WOD: Also Copy equation
below
Strong acids/bases completely dissociate in water, so do not
have Ka values. .Do not confuse . Ka and Kw. .
Ka: How Strong . Kw: How Much .
Weak acids/bases only partly dissociate in water
If Ka value exists, then the reaction is
reversible and the right side is a
conjugate acid/base pair.
Weak acids have small Ka values.
The stronger the weak acid, the larger the
Ka value, the more of the solid that
dissolves.
The words concentrated and dilute indicate
how much of an acid or base is dissolved in solution.
(Molarity)
Not if it is a strong or weak acid/base.
The words concentrated and dilute indicate
how much of an acid or base is dissolved in solution.
(Molarity)
Not if it is a strong or weak
a strong acid can be concentrated or diluted.
A 0.100M solution of methanoic acid is only partially ionized. The [H+] is 2.0 x 10-3 M. What is the acid dissociation constant (Ka) of methanoic
acid?
1. What are 5 equations from this chapter (pH and pOH)?
2. What is the pH and pOH of a 0.000316M solution of HCl?
3. In your own words describe acids and bases (2-3 sentences). (Give examples, pH…)
4. What is the pH and pOH of a 0.00055M solution of NaOH?
1.) pH + pOH = 14 pH= -log[H+]
pOH= -log[OH-]10-pH = [H+]
10-pOH = [OH-]2.) pH=3.5 pOH= 10.5
3.) Individual Descriptions 4.) pH=3.25 pOH= 10.75
Any rain that falls with a pH below 5.6 is considered acid rain
Salts = compoundsconsisting of an anion
from an acid and a cation from
a base. Ex: HCl = H+ + Cl-
NaOH = OH- + Na+
Cl- is an Anion Na+ is a Cation
Put the anion and cation together to form a salt.
neutralization reactionsacids and bases react in water
to produce a salt and water (what kind of reaction is this?)When acids and bases react
in “equal” quantities to make neutral water.(Equal H+ and OH-)
Equivalence point when the number of moles
of hydrogen ions equals the
number of moles of hydroxide ions (neutralized)
What is pH, pOH, [H+], [OH-]?
How many moles of hydrochloric acid are
required to neutralize 0.50 mol of
calcium hydroxide?
How many moles of hydrochloric acid are required to neutralize 0.50 mol ofcalcium hydroxide?
Step 1.) Make sure equation is balanced.Step 2.) List known. Step 3.) List Unknown.Step 4.) Use dimensional analysis to change known to unknown (multiply by molar ratio.
How many moles of hydrochloric acid are
required to neutralize 0.50 mol of
calcium hydroxide?
How many moles of hydrochloric acid are
required to neutralize 0.50 mol of
calcium hydroxide?
How many moles of hydrochloric acid are
required to neutralize 0.50 mol of
calcium hydroxide?
How many moles of hydrochloric acid are
required to neutralize 0.50 mol of
calcium hydroxide?=1
You try it!How many moles of
calcium hydroxide are required to neutralize 1.37
mol of hydrochloric acid?
How many moles of calcium hydroxide are
required to neutralize 1.37 mol of
hydrochloric acid?
TitrationAdding a known amount of base or
acid to an unknown to find the pH of the unknown.
Uses:Equivalence point, End
Point, Neutralization, and
Indicators
TitrationA titration is done to find the
molarity of an unknown solution by neutralization . A pH indicator that changes color at 7 is added. A standard solution of a base such as
Ca(OH)2 is added to an acid until the solution changes color. The known pH of the added base is used to find
the starting pH of the acid.
End Point The point at which the indicator changes color
during a titration.
TitrationShow titration videos
Intro:
http://www.youtube.com/watch?v=3iuVXHxyB1k&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
2 short samples.
http://www.youtube.com/watch?v=g8jdCWC10vQ&safety_mode=true&persist_safety_mode=1&safe=active
http://www.youtube.com/watch?v=s1TCH3Vj2RY&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
Optional. 6min http://www.youtube.com/watch?v=YDzzMcrdyB4&feature=grec_index&safety_mode=true&persist_safety_mode=1&safe=active
Example of caluculations http://www.youtube.com/watch?v=BllRQAc76Y0&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
Find the moles needed to make the solution reach the equivalence point
3 steps to solve a titration:1. Find moles of known or
added H+ or OH-
L x M = n (known) 2. Find moles of unknown.
Use equivalent point: moles of unknown = moles
of known3. Find molarity of
unknown.n / L = M (unknown)
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2.
What is the concentration (molarity) of the HCl
solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 33-mL solution of HCl is completely neutralized by 22-mL of 1.0M Ca(OH)2. What is the concentration (molarity) of the HCl solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity)
of the HCl solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity)
of the calcium hydroxide solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity) of the calcium hydroxide solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity) of the calcium hydroxide solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity) of the calcium hydroxide solution?
A 50-mL solution of Ca(OH)2 is completely neutralized by 25-mL of 1.0M HCl. What is the concentration (molarity) of the calcium hydroxide solution?
Buffer is a solution in which the pH remains
relatively constantwhen small amounts of acid or base are added.
buffer capacity is the amount of acid or base
that can beadded to a buffer solution
before a significant change in pH occurs.
End