more acids, bases & salts › cms › lib2...23 strengths of acids –ternary acids • ternary...
TRANSCRIPT
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Equations
M = n/V
M1V1 = M2 V2 if the moles are the same
n1 n2 you can cancel out the n’s.
pH = -log [H+ ] pOH = -log [OH- ]
pH + pOH = 14
[H3O+] = 10^-pH [OH-] = 10^-pOH
[H3O+] [OH-] = 1.0 x 10-14
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3
Strong Electrolytes
Strong electrolytes ___________ or
___________ completely
Three classes of strong electrolytes
1. ___________ ___________
2. ___________ ___________
3. ___________ ___________
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Properties of Acids
• taste ___________
• change the colors of indicators
• turn litmus paper red
• react with metals to generate _________
• react with ___________ __________ and
___________ to form salts and water
• aqueous solutions conduct ___________
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Properties of Bases
• taste ___________
• feel ___________
• change colors of indicators
• turn litmus paper blue
• react with ___________ to form salts
and water
• aqueous solutions conduct electricity
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Ex. 1) HCl, Ca(OH)2, Al(NO3)3
a) Identify what type of electrolyte each compound is?
b) How many moles of each ion are in an aqueous solution? Assume you start with one mole of each compound.
c) What is the molarity of each ion in 0.500L of water?
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Ex. 1) HCl, Ca(OH)2, Al(NO3)3
a) Identify what type of electrolyte each compound
is?
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Ex. 1) HCl, Ca(OH)2, Al(NO3)3
b) How many moles of each ion are in an aqueous
solution? Assume you start with one mole of
each compound.
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Ex. 1) HCl, Ca(OH)2, Al(NO3)3
c) What is the molarity of each ion in 0.500L of
water?
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Ex. 2) If 200.0 mL of 0.100M HCl and 200.0 mL of
0.100M NaOH are mixed, what is the molarity of
the salt in the resulting soln? (Assume the
volumes are additive)
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Svante Augustus Arrhenius - 1884
___________ are anything that generate H+ in aqueous solutions, while ___________ produce OH- in aqueous solutions
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2322
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32
HCO O H O HH HCO
Cl O H O H HCl
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aqaq OH Na NaOH
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Arrhenius Theory neutralization - combination of H+ (or H3O
+)
with OH-
strong acids - ionize 100% in water
strong bases - ionize 100% in water
Neutralization can also happen with weak acids
and/or weak bases (more on this coming soon)12
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13
Arrhenius Theory
total ionic equation for strong acid with strong
base
(l)O HCl Na OH Na Cl H 2-
aqaq
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aqaqaqaq
net ionic equation for strong acid with
strong base
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14
Bronsted-Lowry Acid Base Theory
2nd definition ___________ - proton (H+) donor
___________ - proton (H+) acceptor
CB CA B A
Br OH OH HBr -32
CB CA A B
OH NH OH NH -423
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15
acid-base reactions are proton transfer reactions
note that we are often making ___________
___________ bonds
___________ between Arrhenius & Bronsted-
Lowry theories
• reaction does not have to occur in an ___________
solution
• bases do not have to be ___________ ~ ammonia is
not a hydroxide
CB CA B A
Cl NH NH HCl -43
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16
Bronsted-Lowry Acid-Base Theory
___________ ___________ ___________ _______
___________ ___________ ___________ _______ primary reason they are weak acids or bases: strong conjugates recombine to form the original species
___________ can be either an acid or base in Bronsted-Lowry theory
It is both amphiprotic and amphoteric ○ ___________ ~ can donate or accept a proton
○ ___________ ~ a substance that can be either an acid or a base.
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17
Amines
___________ are weak bases that behave
like ammonia
amines have organic groups attached to -
NH2 group
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33223
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423
OH NHCH O H NHCH
OH NH O H NH
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18
Strengths of Acids - Binary Acids
acid strength increases with decreasing
bond strength (inversely proportional)
Strongest bond = ___________ ________
hydrogen halides
bond strength
HF>>HCl>HBr>HI
acid strength
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Strengths of Acids - VIA hydrides
bond strength
H2O>> H2S> H2Se>
acid strength
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Strengths of Acids
___________
strongest acid that can exist in water is
H3O+
acids that are stronger than H3O+ merely
react with water to produce H3O+
consequently all strong soluble acids have the
same strength in water
can only distinguish acid strength
differences of strong acids in ___________
solutions like acetic acid (weak acids)
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21
Strengths of Acids
___________ ___________ in water is H3O+
HCl + H2O H3O+ + Cl-
HCl is so strong it forces water to accept H+
___________ ___________ in water is OH-
NH2- + H2O NH3 + OH
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NH2- is strong enough to remove H+ from water
Why? Water is ___________
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22
Strengths of Acids
Acid Conjugate Base
Strongest acid ~ Weakest base
HClO4 ClO4-
H+ (H3O+) H2O
CH3CO2H CH3CO2-
H2O OH-
NH3 NH2-
Weakest acid ~ Strongest base
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23
Strengths of Acids – ternary acids
• ternary acids, also known as oxyacids are acids containing H, O, and another element (usually a nonmetal)
• ternary acid strength usually increases with• increasing number of O atoms on central atom
• increasing oxidation state of central atom
• acids having same central atom, ___________ _______ of central atom is usually strongest acid
HClO < HClO2 < HClO3 < HClO4
HClO < HClO2 < HClO3 < HClO4Cl Cl Cl Cl
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24
Strengths of Acids – ternary acids
weak ternary acids have stronger H-O
bonds than stronger ternary acids
acid strength
HNO2
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25
Lewis Acid Base Theory
3rd definition
___________ – an electron pair acceptor
___________ – an electron pair donor
___________ - coordinate covalent bond
formation
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26
Lewis Theory
sodium fluoride + boron trifluoride
___________ ___________ but not Arrhenius or Bronsted-Lowry
NaF + BF3 Na+ + BF4
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ammonia + HBr
___________ ___________ ___________ ______ but not Arrhenius
NH3 + HBr NH4+ + Br-
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Acidic, Basic, and Neutral Salts
A ___________ is an ionic compound that contains at least one ___________ ion. The salt therefore ___________ completely in water (look at dissociation table)
___________– normal salts: contain no ionizible H atoms or OH groups. These salts have no effect on the pH of a solution. Normally formed between the reaction of a strong acid and strong base. Most alkali and alkaline earth binaries are neutral salts.
Ex. NaCl, KI, LiNO3, CaBr2
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Some salts will produce an acidic or basic solution
when added to water.
___________ ___________ are ionic compounds
that can provide an H+ to a solution; does not
necessarily produce acidic solns. These
compounds are able to ___________ bases.
Normally formed from the reaction of a strong
acid and weak base.
Ex. NH4I , KH2 AsO4, K2 HPO4, NaHSO4 , NaHCO3
NH4 I + H2O H3O+ + NH3 + I
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___________ ___________ are ionic compounds
that increase the OH- concentration. If the
compound has an anion that would make a weak
acid then it’s a basic salt. Can contain unreacted
OH group that can neutralize acids even though
they are not necessarily basic.
Most ___________ metal binary compounds in
water make basic salts. Basic salts tend to be
___________. Can also be formed from the
reaction of a strong base and a weak acid.
Ex. Al(OH)2 Cl, Fe(OH)2 and some anions to
look for F-, CN- , CNS- , H-
NaF + H2O Na+ + OH- + HF
Li2C2O4 + H2O H2C2O4 + Li+ + OH-
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Ex. 3)
a) If 100.0mL of 0.100M HCl and 100.0 mL of
0.0875M NaOH are mixed, what are the
molarities of the solutes in the resulting soln?
b) What is the pH? (Remember: HCl, NaOH,
and NaCl are strong electrolytes)
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Ex. 4) What volume of 0.00350M HCl soln would
neutralize 30.0 mL of 0.00100M Ca(OH)2
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Ex. 5)
a) Find the molarity of 37.7 mL of H2SO4 when it is
titrated with 42.2 mL of 0.236M NaOH.
b) What is the pH of the acid?
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Ex. 6) A 150.0 mL sample of 0.275M lithium
hydroxide completely reacts with 294.3 mL of
phosphoric acid. What is the molarity of the
acidic solution?
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Ex. 7) if [OH-] = 7.2 x 10-6 M what is the pH?
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Ex. 8) when pH = 7.706 what is [H3O+]?
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Ex. 9) [H3O+]= 1.120 x 10-4 M, pOH = ?
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Ex. 10) [HNO3] = 2.4 M, what is the pH?
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Ex. 11) [H2SO4] = 0.444 M, what is the pH?
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Ex. 12) pH = ? When [Sr(OH)2] = 1.55 x 10-3M
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40
Ex. 13) Calculate the concentrations of H3O+ and
OH- in 0.050 M HCl and find the pH of the solution. Cl OH OH + HCl +32
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41
Ex. 14) Calculate [H3O+], pH, [OH-], and pOH for
0.020 M Ba(OH)2 solution.
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Ex. 15)
a) How many mL of concentrated 12 M HCl will
you need to make 0.500 L of 0.750 M HCl?
b) What is the initial pH?
c) What is the resulting pH?
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Ex. 16) You add 500. mL of water to 500. mL of
1.25 M NaOH. What is the pH of the resulting
solution?
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Ex. 17) A 0.750 g sample of an impure Iron(II)
sulfate is titrated with 26.25 mL of 0.0200M
potassium permangante in an acidified solution
to the endpoint. What is the % purity of the
ferrous sulfate?
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A. One method of increasing the solubility and the absorption of a medication is to convert weakly acidic drugs into sodium salts before making the pills that will be ingested. How does this preparation method enhance the drug’s solubility in the stomach? (hint: stomach acid is about 1M HCl)
B. Medicines that are weakly basic are not absorbed well into the bloodstream. One method to increase their absorption is to take an antacid at the same time that the medicine is administered. How does this method increase the absorption?