Ch. 15 Solutions
• Water is a ___________
bent
molecule
and therefore __________.
polar
• Water forms _______________
hydrogen
________
bonds which strongly bonds the
molecules together with each other.
These intermolecular bonds give
water some very unique properties:
High surface tension: acts like a thin
skin on the surface.
“________”
•
Detergents
_______________
are used to
reduce water’s surface tension so
it can “wet down” a surface such
as clothing.
“Water Strider”
Surface Tension of Water
metal paper clip on water
water forms “beads”
More Unique Properties of Water
Water makes 6-sided (hexagonal) ___________
crystals of ice or snow.
Water readily dissolves other
polar
_____________
substances and ionic
solids/salts.
Aqueous Solutions
•
There are two parts to a solution:
Solvent
1) ____________the dissolving medium which is typically a liquid or
the substance in greater amount when 2 similar phases are mixed
Solute
2) _____________
- the substance that dissolves
Examples of common solutions:
•
sugar in _______
water
Kool-aid = _________
•
O2 in ____
N2
Air = ____
• 14K gold = _______
silver in _________
gold
Examples of common solutions:
•
•
Brass = copper in zinc
__________
Cola Drinks = sugar in water
CO2 in ___________
water
and ______
•
“Like Dissolves Like”
This phrase means that polar solvents dissolve __________
polar
solutes
and nonpolar solvents dissolve ___________
solutes.
nonpolar
Example: Mix together water, oil, table salt, and iodine (I2).
What dissolves in what? ________________
The
nonpolar oil will dissolve the nonpolar I2
____________________________________
and the water dissolves the salt since they are
____________________________________
both polar.
____________________________________
“Like Dissolves Like”
nonpolar grease remover
“Like Dissolves Like”
Vinegar & oil dressing will separate. Shake well before using!
Solution Vocabulary
Miscible
• _______________
: two liquids that can dissolve in each other
Example: ____________
in water
alcohol
•_________________
: the liquids don’t mix
Immiscible
Oil and water
Example: _____
Factors that Affect Solubility
Tested Dissolved Oxygen, Conductivity,
Salinity (salt concentration), and Temperature.
Factors that Affect Solubility
Tested Dissolved Oxygen, Conductivity,
Salinity (salt concentration), and Temperature.
Factors that Affect Solubility
Tested Dissolved Oxygen, Conductivity,
Salinity (salt concentration), and Temperature.
98
%Dissolved Oxygen
96
R² = 0.5653
p=.09
94
92
Plane
90
Sapona
88
86
R² = 0.5977
p=.08
84
0
5
10
15
Distance (m)
20
25
30
38.7
38.6
Salinity (ppt)
38.5
R² = 0.2627
p=.30
38.4
38.3
Plane
Sapona
38.2
R² = 0.4155
p=0.07
38.1
38
37.9
0
5
10
15
Distance (m)
20
25
30
8.1
8.05
R² = 0.6738
p=.57
8
pH
7.95
Plane
7.9
Sapona
7.85
R² = 0.8322
p=.17
7.8
7.75
0
5
10
15
Distance (m)
20
25
30
30.8
30.6
R² = 0.1265
p=.22
Temperature (C)
30.4
30.2
Plane
30
Sapona
29.8
R² = 0.1441
p=.46
29.6
29.4
0
5
10
15
Distance (m)
20
25
30
Measuring the Concentration of a Solution
•
___________________:
Concentration
how much solute is dissolved in a certain
amount of solvent at some given temperature and pressure.
Qualitative Vocabulary
•
•
Dilute
_______________
: contains a small amount of solute
Concentrated : contains a large amount of solute
_______________
concentrated
dilute
Quantitative Vocabulary:
•
•
____________:
Molarity
moles of solute per liter of solution
_______________
( M ) = moles of solute ÷ Liters of solution
Molarity
Practice Problem: What is the molar concentration of an aqueous
NaCl solution when 25.0 grams are dissolved in water to make 500
mL of solution?
1 mol
25.0 g x ________________
= 0.427 mol
58.5 grams
0.427 mol
M = ___________________
0.500 L
Molarity = 0.855 M
Making a Solution of a Required Concentration
# of moles
÷
# of liters
= Molarity
Making Dilutions
•
Dilution: Making a solution _______
less concentrated by ________
adding
more ___________
.
solvent
Important: When diluting acids:
“Add acid to water, do as you ought-er.”
M1xV1=M2xV2
M1 -- the initial concentration of the solution.
V1 -- the initial volume of the original solution that is going to be diluted with water.
M2 -- the final concentration of the solution after it’s diluted with water.
V2 -- the total volume of the final solution after it has been diluted with water.
Making Dilutions
M1xV1=M2xV2
Practice Problems:
1) The science department buys HCl in large bottles that have
a concentration of 12 Molar. The science teacher then dilutes
the acid for labs. How would the teacher make 2.0 liters of a
2.5 M HCl solution from this “stock” solution?
( 12 M ) ( V1 ) = ( 2.5 M ) ( 2.0 L )
V1 = 0.417 L
Take 0.417 L of the stock solution and add it to some water and then add enough water to
make a final volume of 2.0 liters.
2) What is the final concentration of a sugar solution if 300 mL of
water is added to 500 mL of a 2.5 M sugar solution?
( 2.5 M ) (500 mL) = ( M2 ) ( 800 mL )
M2 = 1.56 M
Calibration Curves
•
•
A standard solution is a solution of__________________.
known concentration These
solutions can be used to predict properties of an unknown solution.
three
At least _________
data points are used and then plotted with a line
of best fit.
Beer’s Law
Calibration Curves
•
If spectrometer reads the absorbance at 0.48 what is the molarity?
•
3.12 M
What would you predict the absorbance of a 7M solution to be?
0.62
Ch. 20 Notes -- Acids and Bases
What makes something an acid?
Acid Properties:
sour
lemons
(1) tastes _______-_______________
metals
(2) corrosive to _________
H+ ] (or [ _____
H3O+ ] = “_______________”
hydronium
(3) contains [ ___
ions)
(4) proton ([ ___
Brønsted-Lowry Theory
H+ ]) __________-donor
Example: HCl + H2O 
______
Cl−
+
H
O
3
+ ______
Properties of Bases
What make something a base?
Base Properties: (…the opposite of acid properties)
bitter -- ___________
banana peel ,
(1) tastes ________
parsley, dark chocolate
(2) feels _____________
slippery
-- ________
soap
OH− ] ions
(3) contains [ _____
acceptor
(4) proton ([H+]) ______________-Brønsted-Lowry Theory
NH4+ + _______
OH−
Example: NH3 + H2O  ______
Common Bases
Examples of Common Acids:
•
citrus juices, ___________,
aspirin
Pepsi, _________
stomach acid, battery
acid, _____________,
vinegar
______
DNA
•
Common Bases
Examples of Common Bases: milk of magnesia, ___________,
ammonia
antacid
baking
drain cleaner, soap, blood, ____________
tablets, ___________
________.
soda
•
Indicators
An indicator is a chemical that will change ___________
colors
when
placed in an acidic, basic or neutral environment.
Indicator Colors For Acids
•
•
•
•
red
litmus paper = _______
clear
phenolphthalein = ___________
red cabbage juice (universal indicator) = ________
red
methyl orange = _______
red
•
•
•
•
Indicator Colors for Bases
litmus paper = _______
blue
yellow
methyl orange = ____________
blue
red cabbage juice (universal indicator) =________
phenolphthalein = ______
pink
phenolphthalein
Acid
Base
Universal pH Paper : Indicator Colors
Neutral
Acidic
Basic
•
Acid Vocabulary
strong acid - readily ___________
dissociates to produce ______
many [H+] ions in
water
H2SO4
Examples: _________,
HCl
HNO3, _______
•
small
weak acid - produces a __________
amount of [H+] ions when in
water
H2CO3 lemon
juice
Examples: HC H O (vinegar) , _________,
_________
2
3
2
•
Base Vocabulary
strong base- readily __________
dissociate to produce ______
many [OH−] ions in
water
Examples: NaOH , ________
KOH
•
small amount of [OH−] ions when in
weak base- produces a __________
water
NH3 (ammonia); Mg(OH) (milk of magnesia)
Examples: _____
2
Other Vocabulary
•
•
_______________another term for basic solutions
Alkaline
Amphoteric
_______________a substance that can act as both an acid and a base
−
H
O
HCO
2
3
Examples: ___________
, ____________
Measuring the Amount of H+ and OH− Ions in a Solution
•
•
_____
pH Scale- measures the _____________
concentration of [H+] ions in a solution
pOH Scale- measures the concentration of [ ____
OH− ] ions in a solution
_____
Formulas
pH = − (log [H+])
[H+] = 10−pH
[H+] x [OH−] = 1 x 10−14
•
pOH = −(log [OH−])
[OH−] = 10−pOH
pH + pOH = 14
With the pH scale, we have another way to define acids and bases:
below
Acids have a pH _________7.0
above
Bases have a pH _________7.0
=
Neutral pH ___7.0
pH Testing
Alkalinity Testing
Practice Problems:
1)
Calculate the pH of a 0.001 M HCl solution
[H+] = 0.001 M
2)
So…pH = − (log 0.001 M)
What is the pH of a 4 x 10-9 M KOH solution?
[H+] = 4 x 10-9 M So…pH = − (log 4 x 10-9 M)
3)
pH = 8.3
What is the concentration of [H+] ions in a NaOH solution with a
pH of 8.50?
[H+] = 10−pH
4)
pH = 3
[H+] = 10−8.5 Molar or 3.16 x 10−9 M
What is the concentration of [H+] ions in a HNO3 solution with a
pH of 1.50
[H+] = 10−pH
[H+] = 10−1.5 Molar or 0.0316 M
Neutralization Reactions
salt
When an acid and base are mixed, the reaction produces _______
water
and ___________.
•
•
If the initial concentrations and volumes of the reactants are equal,
neutral
the products will be ____________...
(pH= 7.0)
double
All neutralization reactions are ___________
replacement
reactions.
H2O
HX + M(OH)  ______
MX
+ ______
(“Salt”)
•
•
•
•
•
Titration
Mixing an acid with a base to
determine a __________________
concentration
is called “titration.”
An ____________
indicator is used to
determine when neutralization has
occurred.
Standard
________________
Solution - the
solution of known concentration
End _________
Point - the point of
______
neutralization when titrating
end point, the moles of
At the ______
[H+] ions = moles of [OH−] ions.
Determining the Concentration of an Acid (or Base) by Titration
(Macid)x(Vacid) = (Mbase)x(Vbase)
Practice Problems:
(1) A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M
NaOH standard solution using phenolphthalein as an indicator.
What is the concentration of the HNO3 solution?
( Macid ) x ( 25 mL ) = ( 1.0 M ) x ( 18 mL )
Macid = 0.72 Molar
(2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of
a 0.76 M HCl standard solution?
(0.76 M ) x ( 55 mL ) = ( 2.0 M ) x ( Vbase )
Vbase = 20.9 mL