unit 10: solutions name: _______________________ solution definitions s olution: a homogeneous mixture -- -- e.g., alloy: a so
Unit 10: Solutions Name: _______________________
Solution Definitions
s olution: a homogeneous mixture
--
-- e.g.,
alloy: a solid solution of metals
-- e.g.,
solvent: the substance that dissolves the solute
soluble: “will dissolve in”
miscible: refers to two liquids that mix evenly in all proportions
-- e.g.,
F actors Affecting the Rate of Dissolution
1. temperature
2. particle size
3. mixing
4. nature of solvent or solute
C lasses of Solutions
aqueous solution:
amalgam:
e.g.,
tincture:
e.g.,
organic solution:
e.g.,
Non-Solution Definitions
insoluble: “will NOT dissolve in”
e.g.,
immiscible: refers to two liquids that will NOT form a solution
e.g.,
suspension: appears uniform while being stirred, but settles over time
e.g.,
Molecular Polarity
nonpolar molecules: -- e– are shared equally
-- tend to be symmetric
e.g.,
polar molecules: -- e– NOT shared equally
e.g.,
“Like dissolves like.”
Using Solubility Principles
C hemicals used by body obey solubility principles.
-- water-soluble vitamins: e.g.,
-- fat-soluble vitamins: e.g.,
Dry cleaning employs ___________ liquids.
-- ________ liquids damage wool, silk
-- also, dry clean for stubborn stains (ink, rust, grease)
-- tetrachloroethylene was in
longtime use
emulsifying agent (emulsifier): --
--
e.g., soap detergent lecithin eggs
soap vs. detergent
-- --
--
Hard water contains minerals w/ions like Ca2+, Mg2+, and Fe3+ that
replace Na+ at polar end of soap molecule. Soap is changed
into an insoluble precipitate (i.e., soap scum).
micelle: a liquid droplet covered w/soap or detergent molecules
Solubility
unsaturated: sol’n could hold more
solute;
saturated: sol’n has “just right” amt.
of solute;
supersaturated: sol’n has “too much” solute
dissolved in it;
Solids dissolved in liquids Gases dissolved in liquids
As To , solubility ___ As To , solubility ___
Solubilities of Selected Solutes in Water
EX. Using an available solubility curve, classify as unsaturated,
saturated, or
supersaturated.
per
100 g
H2O
80 g NaNO3 @ 30oC
45 g KCl @ 60oC
30 g KClO3 @ 30oC
70 g Pb(NO3)2 @ 60oC
Per 500 g H2O, 100 g KNO3 @ 40oC
EX. Describe each situation below.
( A) Per 100 g H2O, 100 g NaNO3 @ 50oC.
( B) Cool sol’n (A) very slowly to 10oC.
( C) Quench sol’n (A) in an ice bath to 10oC.
Glassware – Precision and Cost beaker vs. volumetric flask
1000 mL + 5% 1000 mL + 0.30 mL
When filled to 1000 mL line,
how much liquid is present?
Concentration…a measure of solute-to-solvent ratio
concentrated dilute
Selected
units of
concentration
A. mass % = mass of solute x 100
mass of sol’n
B. parts per million (ppm) = mass of solute x 106
mass of sol’n
also, ppb and ppt
-- commonly used for minerals or contaminants in water supplies
C. molarity (M) = moles of solute
L of sol’n
-- used most often in this class
EX. How many mol solute are req’d to make 1.35 L of 2.50 M sol’n?
What mass sodium hydroxide is this?
What mass magnesium phosphate is this?
EX. Find molarity if 58.6 g barium hydroxide are in 5.65 L sol’n.
EX. You have 10.8 g potassium nitrate. How many mL of sol’n will make
this a 0.14 M
sol’n?
M olarity and Stoichiometry
EX. __Pb(NO3)2(aq) + __KI (aq) __PbI2(s) + __KNO3(aq)
What volume of 4.0 M KI sol’n is req’d to yield 89 g PbI2?
Strategy: (1)
(2)
EX. How many mL of a 0.500 M CuSO4 sol’n will react w/excess Al to
produce 11.0 g Cu?
Dilutions of Solutions Acids (and sometimes bases) are purchased in
concentrated form (“concentrate”) and are easily diluted to any
desired concentration.
**Safety Tip:
Dilution Equation:
EX. Conc. H3PO4 is 14.8 M. What volume of concentrate is req’d to make
25.00 L of
0.500 M H3PO4?
How would you mix the above sol’n?
1. Measure out ________ L of conc. H3PO4.
2. In separate container, obtain ~20 L of cold H2O.
3. In fume hood, slowly pour H3PO4 into cold H2O.
4. Add enough H2O until 25.00 L of sol’n is obtained.
EX. You have 75 mL of conc. HF (28.9 M); you need 15.0 L of 0.100 M
HF. Do you have
enough to do the experiment?
Dissociation occurs when neutral combinations of particles
separate into ions while in aqueous solution.
sodium chloride NaCl
sodium hydroxide NaOH
hydrochloric acid HCl
sulfuric acid H2SO4
acetic acid CH3COOH
In general, ________ yield hydrogen (H+) ions
in aqueous solution; ________ yield hydroxide (OH–) ions.
Strong electrolytes exhibit nearly 100% dissociation.
NaCl Na+ + Cl–
NOT in water:
in aq. sol’n:
Weak electrolytes exhibit little dissociation.
CH3COOH CH3COO– + H+
NOT in water:
in aq. sol’n:
electrolytes: solutes that dissociate in sol’n
-- conduct elec. current because of free-moving ions
-- e.g.,
-- are crucial for many cellular processes
-- obtained in a healthy diet
--
nonelectrolytes: solutes that DO NOT dissociate
--
-- e.g.,
Colligative Properties
Compared to solvent’s… a sol’n w/that solvent has a…
…normal freezing point (NFP)
…normal boiling point (NBP)
Applications of Colligative Properties (NOTE: Data are fictitious.)
EX. salting roads in winter
FP
BP
water
water + a little salt
water + more salt
EX. antifreeze (AF) (a.k.a., “coolant”)
FP
BP
water
water + a little AF
50% water + 50% AF
EX. law enforcement
white powder
starts
melting at…
finishes
melting at…
penalty, if
convicted
A
B
C
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