Ch. 16 Notes -- Acids and Bases What makes something an acid? Acid Properties : (1) tastes _______-- _______________ (2) corrosive to _________ (3) contains [ ___ ] (or [ _____ ] = “_______________” ions) (4) proton ([ ___ ]) __________-- Brønsted- Lowry Theory sour lemons metals H + H 3 O + hydroniu m H + donor Cl − H 3 O +
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Ch. 16 Notes -- Acids and Bases What makes something an acid?
Strong Bases vs. Weak Bases• strong base- readily __________ to produce ______ [OH−] ions in
water
Examples: NaOH , ________
• weak base- produces a __________ amount of [OH−] ions when in water
Examples: _____ (ammonia); Mg(OH)2 (milk of magnesia)
Other Vocabulary
• _______________- another term for basic solutions
• _______________- a substance that can act as both an acid and a base
Examples: ___________ , ____________
dissociate many
KOH
small
NH3
Alkaline
Amphoteric
H2O HCO3−
Self-Ionization of Water• Pure water is _____________. It can ionize itself to form OH− and
H3O+ ions in __________ amounts.
H2O + H2O H3O+ + OH−
(or H2O _______ + _______ )
• The universal indicator color is ___________ in neutral solutions.
neutralsmall
H+ OH−
green
self-ionization of water
Measuring the Amount of H+ and OH− Ions in a Solution
• _____ Scale- measures the _____________ of [H+] ions in a solution
• _____ Scale- measures the concentration of [ ____ ] ions in a solution
Formulas
pH = − (log [H+]) pOH = −(log [OH−])
[H+] = 10−pH [OH−] = 10−pOH
[H+] x [OH−] = 1 x 10−14 pH + pOH = 14
• With the pH scale, we have another way to define acids and bases:
Acids have a pH _________7.0
Bases have a pH _________7.0
Neutral pH ___7.0
pH concentration
pOH OH−
below
above
=
Practice Problems:
1) a) Calculate the pH of a 0.001 M HCl solution
b) Is this an acid or a base?
2) a) What is the concentration of [H+] ions in a solution that has a pH of 8.50?
b) Is this an acid or a base?
[H+] = 0.001 M So…pH = − (log 0.001 M) pH = 3
[H+] = 10−pH [H+] = 10−8.5 Molar or 3.16 x 10−9 M
Acid!
Base!
pH Testing
Alkalinity Testing
Neutralization Reactions
When an acid and base are mixed, the reaction produces _______
and ___________.
• If the initial concentrations and volumes of the reactants are equal, the products will be ____________... (pH= 7.0)
• All neutralization reactions are ___________ replacement reactions.
HX + M(OH) ______ + ______
salt
water
neutral
double
MX H2O(“Salt”)
Titration• Mixing an acid with a base to
determine a __________________ is called “titration.”
• An ____________ is used to determine when neutralization has occurred.
• ________________ Solution - the solution of known concentration
• _________________ - the point of neutralization when titrating
• At the eqivalence point, the moles of [H+] ions = moles of [OH−] ions.
• The “_____ Point” is when the indicator changes color.
concentration
indicator
Standard
Equivalence Point
End
Titration Curve
Practice Problems:
(1) Complete the following neutralization reactions.
HNO3 (aq) + KOH (aq) _________ + __________
HCl (aq) + Ca(OH)2 (aq) __________ + ___________
(2) How many moles of Ca(OH)2 will it take to neutralize 0.5 moles of HCl?
3) How many moles of HNO3 will it take to neutralize 3.0 moles of KOH?
KNO3 H2O
CaCl2 H2O2 2+2 −1
2 moles HCl1 mole Ca(OH)20.5 moles HCl x = 0.25 moles of Ca(OH)2
1 mole KOH1 mole HNO33.0 moles KOH x = 3.0 moles of HNO3
(Macid)x(Vacid) = (Mbase)x(Vbase)
Practice Problems:
(1) A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO3 solution?
(2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of a 0.76 M HCl standard solution?
Determining the Concentration of an Acid (or Base) by Titration