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Ions in Aqueous Solution & Colligative Properties Chpt. 14
I. Compounds in aqueous solution
A. Dissociation -___________________________________________________
__________________________________________________________________
1. always assume the ions have 100% dissociation
2. indicate ions produced & # of moles produced
NaCl(s)  Na+(aq) + Cl–(aq)
__________________________________________
3.Not all ionic compounds are soluble in water.
4. Precipitation Reactions ________________________________________
__________________________________________________________________.
To determine which it is use a solubility chart .
a. precipitate – _______________________________________________
___________________________________________________________________
___________________________________________________________________
5. Net ionic equation = an equation that includes _______________________
___________________________________________________________________
a. _________________________ = ions that don’t take part in a chem
reaction & are found in solution both BEFORE & AFTER the reaction –
these ions ____________________________ in a net ionic equation
b. LOOK FOR A PRECIPITATE! __________________________________
_________________________________________________________________
c. How to write net ionic equations:
1) Start with a balanced equation (predict products if needed)
(NH4)2S
(s)
+ Cd(NO3)2(s)
water
2NH4NO3 +CdS
2) Write all strong electrolytes as ions (write them dissociated) :
electrolytes = substances that conduct electricity in solution
Use your Ion Chart!!!
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(NH4)2S
(s)
a) _________________________: HCl, HBr, HI, and any oxygen
containing acid with 2 or more oxygens (all organic acids --contain carbon-- are
weak electrolytes)
b) ______________________________: hydroxides of group I
metals and barium and strontium are strong electrolytes
c) ____________________________: NaCl
→ NH4+(aq) + S-2(aq)
Cd(NO3)2(s) → Cd+2 (aq) + 2NO3-1(aq)
soooooo…
NH4+(aq) + S-2(aq) + Cd+2 (aq) + 2NO3-1(aq)
double replacement reaction
Hints: Oxides, gases,and water are always written as molecular or undissociated
3) _____________________________________ to see which
new cmpd is insoluble.
NH4+(aq) + S-2(aq) + Cd+2 (aq) + 2NO3-1(aq)
NH4NO3(aq) + CdS (s)
4) ____________________________________________ (ions
that are the same on the reactant and product side of the equation –if they
stay dissolved then they are considered the same so, look for a precipitate…. something
insoluble in water!)
NH4+(aq) + S-2(aq) + Cd+2 (aq) + 2NO3-1(aq)
NH4+(aq) +
NO3-1(aq) + CdS (s)
5) Write the Net Ionic equation ____________________________
__________________________________________________________________
Cd+2 (aq) + S-2(aq)
CdS (s)
B. Ionization - ____________________________________________________
_________________________________________________________________
(it’s the creation of ions where none previously existed!)
1. _______________________ are polar molecules that ionize in water
HNO3(aq) + H2O(l)  H3O+(aq) + NO3–(aq)
(H3O+ is the ________________________ we’ll talk about it with acids)
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C. Molecular Solvation _______________________________________________
___________________________________________________________________
C6H12O6(s)  C6H12O6(aq)
these substances are nonelectrolytes!
II. Colligative Property- ______________________________________________
__________________________________________________________________---Changes in the behavior of the solutions that are due primarily to the concentration of
solute particles rather than the typical properties of those substances are known as
colligative properties.
A. Types
1. Freezing Point Depression (tf)
a. _____________________________________________________
t: change in temperature (°C)
kf: constant based on the solvent (°C·kg/mol) page p.445 in the book
m: molality (m)
n: # of (ion) particles in solution (1 for non-electrolytes & you must write net
ionic equations to find # for electrolytes)
2. Boiling Point Elevation (tb)
a. ____________________________________________________
t:
change in temperature (°C)
kb:
constant based on the solvent (°C·kg/mol) page p.445 in the book
m:
molality (m)
n:
# of (ion) particles in solution (1 for non-electrolytes & you must write net
equations to find # for electrolytes)
ionic
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3. Osmotic pressure – _________________________________________
__________________________________________________________________-the greater the # of particles the greater the osmotic pressure!
a. ___________________ – _________________________________
__________________________________________________________________
from the side of lower [SOLUTE] to the side of higher [SOLUTE]
OR
the _______________________________________________
________________________________________________________________
b. eventually the concentrations of the 2 solutions become equal
___________________________________
c. increasing the number of dissolved particles __________________
__________________________________________________________________
d. Osmotic Pressure of the Blood
1) ___________________________________________________
2) The osmotic pressure of blood cells cannot change or damage occurs.
3) The flow of water between a red blood cell and its surrounding
environment must be equal (______________________solution)
a) Medically 5% glucose and 0.9% NaCl are used (their solute
concentrations provide an osmotic pressure equal to that of red
blood cells)
b) _______________________ Solutions
Lower osmotic pressure outside the cell than inside the cell
_______________________________________________
____________________________________________________
In a hypotonic solution, water flows ___ to the cell
The RBC undergoes _______________; it swells and
may burst.
*Greater concentration of water outside cell than inside so
water moves into the cell.
c) ________________________ Solutions
Has higher osmotic pressure (more dissolved particles) than
the RBC
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Has a higher particle concentration
In hypertonic solutions, water flows ______ of the cell
The RBC shrinks in size/shrivels (____________________)
*Greater concentration of H2O inside cell than outside so
water moves out
B. Applications
1. salting icy roads – _____________________________________________
___________________________________________________________________
2. making ice cream -lowers the f.p. of ice & causes it to melt – when something melts
it is an _______________ process!! It pulls E (heat) from the milk mixture making it colder
3. antifreeze – lowers f.p. of water & increases b.p. of water in radiator
(-64°C to 136°C)
4. Dialysis
a. Normal cleaning of the blood occurs when ______________ with
small solute particles pass through a semipermeable membrane in kidney
b. Large particles retained inside blood small stuff moves through to
kidney & then to _________________________
c. __________________ is used medically (artificial kidney) to remove
waste particles such as urea from blood when kidney no longer functions
C. Calculations
t:
kf:
m:
1.Find the freezing point of a saturated solution of NaCl containing
28g NaCl in 100. mL water.
NaCl
Na+ + Cl?
1.86 (°C·kg/mol)
4.8 m
28g convert to moles = .48mol then…
.48mol/.100kg = 4.8 m
n:
2 ions
t = kf x n x
m
Δt = 1.86(°C·kg) x 2 x 4.8mol = 17.856 °C you’re not finished yet!!
mol
kg
normal f.p. of water is 0°C so 0°C – 17.856 = -17.856°C