1. Describe the following terms
• Solution
• Solvent
• Solute
• Soluble
• Insoluble
• Miscible
• Immiscible
Homogeneous mixtures of 2 or more substances
Dissolving medium
Substance that dissolves
Will dissolve
Won’t dissolve
Liquids are soluble in one another
Liquids aren’t soluble in one another
2. Examples of the solutions
• Solid in a liquid
• Gas in a liquid
• Solid in a solid
• Gas in a gas
Salt water
Carbonated beverage
Steel/braces
Air
3
• Describe what happens as a crystal of salt (NaCl) dissolves in water.
Charged ends of water are attracted to the ions in salt
This attraction is strong enough to pull the ions away
4
• How is the dissolving process different in sugar (compared with salt)?
OH bonds attract H of H2O molecules until sucrose molecule is surrounded by many H2O molecules, which then pull entire sucrose molecule away
5
• Why doesn’t oil dissolve in water? Would oil dissolve in anything?
Oil is nonpolar and water is polar. Oil would dissolve in a nonpolar solvent.
6
• What is solubility?
Maximum amount of solute that will dissolve in a given amount of solvent at a specific temperature and pressure.
7. How does temp affect solubility?
• For solids?
• For gases?
– What else changes gas solubility?
As temp increases, solubility increases
As temp increases, solubility decreases
pressure
8
• What three things can be done to increase the rate at which a solid dissolves?
a. Agitate the mixture
b. Increase surface area of solute
c. Increase temperature of solvent
10
• How would you prepare a supersaturated sugar solution? Include the term “seed crystal”.
Make a saturated solution at a high temperature. Then cool slowly so excess solute remains dissolved at a lower temp. when a seed crystal is added, the entire solution will crystalize.
11
• What is one test you could do to determine if a solution was saturated, unsaturated, or supersaturated? Describe how the results would be different for unsaturated, saturated, supersaturated solutions.
Add more solute: unsaturated solution, it will dissolve
saturated solution, it won’t dissolve
supersaturated solution, a seed crystal will cause the solution to crystallize
13
• What does solution concentration describe?
Molarity: amount of solute dissolved in a given amount of solvent
16
• What does it mean to dilute a solution? What equation do we use for dilutions?
To lower its concentration “water it down”
M1V1 = M2V2
17
• What is the molarity of a sodium chloride solution that contains 1.73 moles in 3.94 L of solution?
1.730.439
3.94
mol molM M
L L
18
• What is the molarity of sodium hydroxide solution that contains 23.5 g NaOH in 500.0 mL of solution?
1 0.58823.5 1.18
40.00 0.5000
mol molgNaOHx M
g L
19
• How many grams of potassium nitrate are in 275 mL of 1.25 M solution?
1.25 0.3440.275
xM mol
L 3KNO
101.1134.8
1
gx g
mol 3KNO
20
• How many mL of 3.25 M hydrochloric acid would contain 16.0 grams of solute?
116.0 0.439
36.46
molgHClx mol
g
0.4393.25 135
molM mL
x
21
• You have 12.0 M HCl in your stock room, how would you prepare 600.0 mL of 2.50 M HCl solution?
(12.0 M)(x) = (2.50 M)(600.0 mL)
X=125 mL
Measure out 125 mL of stock solution. Add 475 mL of distilled water.
22
• How would you correctly prepare 500.0 mL of a 3.0 M solution of NaOH from solid solute?
3.0 1.50.5000
xM mol
L NaOH
40.0060
1
gx gmol
Measure out 60 g of NaOH (s)
Add water to the 500.0 mL line
23
• How would you prepare 500 mL of 3.0 M NaOH from 12.0 M concentrated stock solution?
(12.0 M)(X) = (3.0 M)(500 mL)
X=125 mL
Measure out 125 mL of stock solution. Add it to 375 mL of distilled water
26
• An excess of zinc is added to 125 mL of 0.100 M HCl solution. What mass of zinc chloride is formed?
Zn + 2HCl ZnCl2 + H2
0.1000.125
xM
L
29
• Polar molecules: one of these shapes:
• Must have ______ bonds (electronegativity difference between 0.4-2.1)
Dumbbell, bent, trigonal pyramidal
Polar covalent
30• Molecules that won’t dissolve in water
include anything with ____ bonds (electronegativity differences less than 0.4)
• Symmetrical shapes such as:
• These substances might dissolve in:
nonpolar
Linear, trigonal planar, tetrahedral
Oil