in Solution AP Chemistry solvent solution a homogeneous mixture of two or more substances The is present in greatest quantity Any other substance present is called a ID: 309479
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Slide1
Reactionsin Solution
AP ChemistrySlide2
solvent
solution: a homogeneous mixture of
two or more substances
-- The
______
is present in greatest quantity.
-- Any other substance present is called a ______.
aqueous solutions: solutions in which water is the dissolving medium (i.e., the solvent)
electrolyte: any substance whose aqueous solution will conduct electricity
e.g.,
-- as opposed to a nonelectrolyte, e.g.,
solute
HCl, NaCl, KOH
any sugar (C6H12O6, C12H22O11)
or any alcohol (CH
3
OH, CH
3
CH
2
OH)Slide3
+
As a general rule, ionic solids
dissociate
into ions in
aqueous solution. The partial
(–) charge on the O andthe partial (+) charge on the H atoms allow H
2O tointeract strongly with, and “pull out,” ions in the
crystallattice. Thus, ionic compounds are often strongelectrolytes.
O
H
H
–
+
–+
–
+
–
+
–
+
–
+
–
–
+
–
+
–
+
–
+
–
O
H
H
+
O
H
H
O
H
H
O
H
H
O
H
H
d
+
d
+
d
–
+Slide4
For molecular compounds, structural integrity ofmolecules is maintained. Substance may
dissolve,but generally won’t split into ions. Thus, mol. comps.tend to be nonelectrolytes.
-- major exceptions:
acids and NH
3
(
ammonia)
**
When molecular compounds DO split into ions,
it is called
ionization
, not dissociation.Slide5
Strong electrolytes exist almost completely as ions
in aqueous solution.
e.g.,
Weak electrolytes
produce only a small concentration
of ions in reaching equilibrium
.e.g.,
HCl(aq) H+(aq) + Cl
–(aq)
KCl(aq) K
+(aq) + Cl–(aq)
lots of
product
CH3COOH(aq) CH3COO–
(aq) + H+(aq)
HF(aq) H
+
(aq) + F
–
(aq)
lots of
reactant
(note the one-sided arrow)
(note the double arrow)Slide6
Some of the strong electrolytes are thestrong acids
and strong bases.
STRONG ACIDS
STRONG BASES
the hydroxides of...
“strong base cations”
Li, Na, K, Rb,
Cs, Ca, Sr, Ba
hydrochloric, HCl
hydrobromic, HBr
hydroiodic, HI
chloric, HClO
3
perchloric, HClO
4
nitric, HNO
3
sulfuric, H
2
SO
4
Slide7
If… “most”
Be careful to distinguish
between
dissolution and dissociation/ionization
in
regard to
strongs or weaks
. Forexample, CH3COOH dissolves completely, but ionizesonly slightly; it is therefore a
weak electrolyte. On theother hand, Ba(OH)2 dissolves very little, but
theamount that does dissolve dissociates almostcompletely. Ba
(OH)2 is a strong electrolyte.
The question is: Of the amount that dissolves, what fraction dissociates/ionizes?
If… “not much”
STRONGWEAKSlide8
Precipitation reactions are reactions in solution that
form an insoluble product.
The insoluble product is called a...
precipitate.
Solubility Guidelines for Selected Ions
in Aqueous Solution
Soluble
Insoluble
no exceptions
except with Hg
2
2+
, Ag
+
,
and
Pb
2+
except with Hg
2
2+
, Ba
2+
,
Sr
2
+
,
and
Pb
2+
except with Alk+
and NH4+
except with NH4
+ and “strong base cations”
CH3COO–, Alk
+,
Br–, I–,
Cl–
SO42–
PO4
3–, CrO42–, CO
32–
S2–
, OH–
NO3–, NH
4+ Slide9
Soluble
no exceptions
except with Hg
2
2+
, Ag
+
,
and
Pb2+
except with Hg
22+, Ba
2+, Sr2+, and Pb2+CH3COO–,
Alk+,
Br
–
,
I
–
,
Cl
–
SO
4
2–
NO
3
–
,
NH
4
+
sol
Br
–, I–
, Cl–
Hg
22+
Ag
+
Pb
2+
sol
SO
4
2–
Hg2
2+
Pb
2+
Ba
2+
Sr2+
Saul Sulf
ate two huge bars… and peanut butter, too.
Saul
Brickell double-hugged Agatha… and Paul Bunyan, too.
Saul ‘Chuck’
Cooawlkay knows exceptions? Naaaah
.
sol
CH
3COO– Alk
+
NH4+
NO
3
– Slide10
Insoluble
except with
Alk
+
and NH
4
+
except with NH
4
+
and “strong base cations
”
PO4
3–, CrO42–, CO32–S
2–, OH–
“The poor crow was cold; he huddled with everyone, but Al K. said, “
Naaaah
.”
PO
4
3–
Alk
+
NH
4
+
“
Soooooo
… You two are always combined.”
“
Naaaaht
when we’re strongly basic.”
CrO
4
2–
CO
3
2–
S
2–
OH
–
NH
4
+
SBCs Slide11
Saul ‘Chuck’
Cooawlkay knows exceptions? Naaaah
.
the honorable, no-nonsense judge: Saul ‘Chuck’
Cooawlkay
sol
CH
3
COO
–
Alk+
NH4
+
NO3– Slide12
Saul
Brickell double-hugged Agatha… and Paul Bunyan, too.
sol
Br
–
,I
–
,
Cl
–
Hg
2
2+ Ag+
Pb2+
Saul
Brickell
double-hugging Agatha
Saul
Brickell
double-hugging
the Paul Bunyan trophySlide13
Saul
Sulf
ate two huge bars… and peanut butter, too.
the slightly sickened
Saul
Sulf
sol
SO
4
2–
Hg
2
2+
Pb
2+
Ba
2+
Sr
2+
t
wo HUGE, “I’m-going-
into-a-sugar-coma” bars
peanut
butterSlide14
The poor crow was cold; he huddled with everyone, but Al K. said, “
Naaaah.”
PO
4
3–
Alk
+
NH
4
+
CrO
4
2–
CO
3
2–
the poor
crow who
was cold
the poor crow
who was cold
attempting to
huddle with
everyone
the somewhat aloof
Al K. politely
declining the
crow’s overtures
to huddleSlide15
‘
Soooooo… You two are always combined.’
“
Naaaaht
when we’re strongly basic.”
S
2–
OH
–
NH
4
+
SBCs
“OH!”Slide16
(aq)
Suppose you mix solutions oflead(II) nitrate and sodium iodide.
The ions present are...
Pb
2+
, NO
3
–, Na+, I–
Pb2+ + 2 NO3
– + 2 Na+ + 2 I–
Pb(NO3
)2 NaI
Write the overall ionic equation…
PbI2 + 2 NO3– + 2 Na+
(aq)
(aq)
(aq)
(aq)
(aq)
(ppt)
Cancel the
spectator ions
to
get the
net
ionic equation
…
Pb
2+
+ 2 I
–
PbI
2
(aq)
(aq)
(ppt)