Chemistry unit 9 scaffolded notes[1] (1)

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Unit 9
Solution Chemistry
• 1.__________: A homogeneous mixture
in which 2 substances exist in a single
phase.
• Solutions can exist between any 2.____
__________ of matter.
• 3.__________ are physical combinations
of matter.
– Examples of solutions include salt water, 10
karat gold, and 4.____________.
• Substances which can be mixed to form a
solution are said to be 5._____________.
•
Solutions have 2 components:
1. 6.___________ (does the dissolving) the
part of a solution which is present in the
greatest quantity.
2. Solute: The part of a 7._______________
which is dissolved by the solvent.
•
8.___________ is 78% N2 and 21%O2
therefore N2 is the solvent and O2 is one
of the solutes.
•
In order for particles to be able to be 9._____
in a solvent they must have a particle size
(diameter) of 1 nm or less.
Other Types of Mixtures
• Suspension: A mixture of 2 substances in
which one substance 10.________ _______.
– Particles which have a diameter of 11.________ __
or greater will settle out of a mixture.
– An example of a suspension is 12. ____ ___ ______.
• 13._________: Mixtures in which particles are
too large to be dissolved into solution but small
enough to stay dispersed in the mixture.
• Particles dispersed in a colloid have a diameter
between 14. __________ ______ _________.
•
Colloids can be described as having 2 parts:
1. 15.____________: The medium (substance) in
which particles are dispersed.
2. Dispersed phase: The 16.____________ which are
dispersed in the dispersing medium.
– Examples of colloids include 17_______ __ _____.
– Jello: dispersing medium = water / dispersed phase
= Jello powder
– Fog: Dispersing medium = air / dispersed phase =
water
•
The 18.________ ______ can be used to
determine whether a mixture is a solution or a
colloid.
• 19.____________: A substance which conducts
electricity when dissolved in water.
• All electrolytes produce 20._______ in solution.
• The ions allow 21.__________ ________ to
travel through the solution.
• All salts, acids, and bases are 22.___________.
• Electrolytes dissolve in polar solvents.
• Non-electrolyte: A substance which dissolves in
water but does not conduct electricity.
• Sugar is a 23._________________________.
•
•
•
The Dissolving Process
Dissolving takes place only 24._______ of the
solute as solvent particles collide with the
surface of the solute, pulling solute particles into
solution.
Solute particles dissolve 25.______ particle at a
time.
The Rate of Dissolving
26._________factors will increase the rate of
dissolving: (solid solutes in liquid solvent)
1. Heating the solution: Heating will 27_________ __
_________ of dissolving by increasing the number of
collisions between solute and solvent particles.
2. Agitation: (28._______) Agitation will
increase the rate of dissolving by increasing
the number of collisions between solute and
solvent particles.
3. 29.__________ _______ _______ of
solute: (crushing/slicing) Increasing surface
area of solute increases the rate of
dissolving by increasing the area in which
the solvent particles can come in contact
with solute, hence increasing
30._____________between solute and
solvent particles.
•
•
•
•
Solution Concentration
31._____________ describes the amount of
solute dissolved in solvent.
Saturated solution: A solution which contains
the 32.____________amount of solute dissolved
in solvent at a given temperature.
33._________________ solution: A solution
which contains less than the maximum amount
of solute dissolved in solvent at a given
temperature.
34.______________ ____________ solution: A
solution which contains more than the maximum
amount of solute dissolved in solvent at a given
temperature.
Preparing a Supersaturated Solution
• Example: Preparing a supersaturated sugarwater solution.
1. 35.______ the water
2. Saturate the heated water with sugar
(36.________________________________))
3. Let the water cool.
• When the solution has cooled it will be
37.________________________ because it
contains more solute than it would be able to
contain at a lower temperature.
• Heating the water 38._______________ the
solubility of sugar in water.
•
•
•
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Solubility
Solubility: The amount of substance required to form a
40.______________ with a specific amount of solvent at a
given temperature.
Solubility is 41.___________________ ____________.
For solid solutes in liquid solvents solubility generally
42._________ with increasing temperature. (see pg 404)
For gaseous solutes in liquid solvents solubility decreases
with 43.___________________ temperature.
44.__________________: A physical state in which the
opposing processes of dissolution and reforming of solute
take place at the same rate.
45.____________________ exist in a state of solution
equilibrium. (see pg 408)
•
•
•
•
•
Solute-Solvent Interactions
When a solute particle has been dissolved into
solution that particle is said to be 46._________.
(see page 415 and diagram on board)
“47.______ __________ ______”: Chemically
similar substances dissolve in each other.
Polar solvents dissolve in
48.___________solutes.
49.____________ solvents dissolve non-polar
solutes.
50.______________ describes the ability of
liquids to dissolve in each other.
– Miscible liquids are chemically similar and dissolve in
each other. (i.e. Alcohol and water)
– Immiscible liquids are not chemically similar and do not
dissolve in each other. (i.e. oil and water)
• 51.______________: The solubility of a gas in a liquid is
directly proportional to the partial pressure of that gas on
the surface of the liquid.
• Carbonated soft drinks are bottled under 52.______
which forces carbon dioxide into solution. When the
bottle is opened, the pressure above the solution drops
and the dissolved carbon dioxide effervesces.
• 52.________________________: The rapid escape of a
dissolved gas from a liquid.
• Heat of solution: The net amount of heat energy
53._____________ __ __________ when a specific
amount of solute becomes dissolved.
• When particles become solvated there is a change in
54.__________ ___________ (heat)
•
•
•
Concentration calculations
There are two calculations which can be performed to
describe solution concentration.
1. 55.__________: Describes solution concentration in
terms of volume of solution
• Molarity (M) = (mol) solute ÷ (L) of solution
2. 56.____________: Describes solution concentration
in terms of mass of solvent
• Molality (m) = (mol) solute ÷ (kg) of solvent
Molarity (M) is 57.___________ ________ because
volume changes with changing temperature.
Molality (m) is 58.______ temperature dependent and
can be considered a more accurate measure of
solution concentration
Preparing Molar and Molal Solutions
(see pages 419 and 422 in text and watch demos)
• Preparing Molar solutions requires a volumetric
flask.
• 59.____________: A flask with a long stem
designed for measuring specific volumes of
liquid.
• 1 L of water = 60._________ kg at STP
Colligative Properties of Solutions
• Colligative properties: Properties of solutions
which depend on the 61.__________ of solute
particles in solution rather than on the identity of
the solute particles.
• Dissolving solid solute in liquid solvent has a
tendency to 62.______ ___ _______ _____ of
the solvent and raise the boiling point of the
solvent.
• Solute particles “63. ____ ___ ___ ____” of
solvent particles making it harder for solvent
particles to become locked in a fixed position in
the solid phase, and harder to escape as a
vapor.
• Dissolving solute particles into solvent
64.__________the vapor pressure of nonvolatile liquid solvents.
• Non-volatile means that the liquid does not
65._____________ readily.
• 66.___________ liquids tend to be non-volatile.
• Lowering the 67._________ _________ of a
liquid allows the liquid to remain in the liquid
phase over a greater range of temperatures.
• The 68.________ the concentration of a solution
the lower the vapor pressure of the liquid solvent
becomes.
• 69._____________________: The difference
between the freezing point of a pure solvent (l)
and a solution containing a non-electrolyte
solute.
– The equation for calculating freezing point depression
is as follows: _______ = ________
– ∆tf = freezing point depression
– Kf = molal freezing point constant [-1.86oC] for nonelectrolyte solutes.
– m = 70._______________ of the solution
(concentration)
• 71.__________ ________________: The
difference between the boiling point of a pure
solvent (l) and a solution containing a nonelectrolyte solute.
– The equation for calculating boiling point elevation is
as follows: ∆tb = Kb m
– ∆tb = 72.________________________________
– Kb = molal boiling point constant [73.____________]
for non-electrolyte solutes.
– m = molality of the solution (concentration)
• Boiling point elevation and freezing point
depression are 74.____________ __________
to molal solution concentration.
Electrolytes and Colligative properties
• Electrolytes (75._________ ________ _______)
have a stronger force of attraction to solvent
particles when dissolved in non-volatile solvents
(generally polar)
• The force of attraction between electrolyte solute
particles are 76.____________ than the
attractive pull of volatile solvent particles, so
most electrolyte solutes 77. _____ ______
dissolve in volatile (non-polar) solvents. (the
“pull” of the solvent particles is too weak to
overcome the attraction holding solute particles
together)
• 78.____________, when dissolved in nonvolatile (polar) solvents, dramatically increase
the boiling point and lower the freezing point of
the liquid solvent when compared to nonelectrolyte solutes.
• Adding 79.___________________ to water
lowers the freezing point of the water and
increases the boiling point of the water making it
both a coolant and an anti freezing solution.
• “Salting” a frozen pavement 80.____________
the freezing point of water thus melting the ice
(deicer).
• Salt is added to the ice when making ice cream
so that the liquid water 81.______ “_______” as
to be able to freeze the milk in the ice cream.
Acids, Bases, and pH
• pH = 82._______ __ __________ (measures
the concentration of hydrogen ions in solution)
• Acids have a 83._________ concentration of
hydrogen ions while bases have a low
concentration of hydrogen ions.
• The pH scale ranges from 0 to 14
– 0 = strongest acid
– 14 = strongest base
– 7 = neutral
• Below pH=7 is an 84.__________, above pH=7
is a base.
• pH=7 is 85._____________
Formula for calculating pH
•
•
•
86.__________ = _________________
pH = power of hydrogen
[H3O+] = hydronium ion concentration
1.
2.
3.
4.
5.
Properties of Acids
87.___________ taste.
Corrosive to many metals (not all) and
corrosive to organic compounds (living tissue).
Acids turn 88.________ _______ ______.
Acids react with bases to produce
89.________ ___ _______ through a process
called neutralization.
Acids are 90.___________________.
–
–
Litmus is an indicator.
An indicator is a substance that changes
91.________ in the presence of an acid or base.
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Strength of Acids
Acid strength is determined by the extent to
which the 92._________ ____________ in
solution.
93.____________ acids completely ionize in
solution.
Weak 94.____________ partially ionize in
solution.
When weak acids ionize, the ions 95._______ to
reform solute.
Strong acids are strong 96.______________.
Weak acids are weak electrolytes.
Types of Acids
• 97._______: Acids which contain hydrogen and one
other highly electronegative element dissolved in
water.
– examples: HCl(aq), H2S(aq), H3P(aq)
• Oxyacid: Acids which contain hydrogen and an
98.___________ and are dissolved in water.
– Examples: HNO3(aq), H2SO4(aq), H3PO4(aq)
• 99.________________ acid = An acid which
donates only one proton (hydrogen ion) ex: HCl
• Diprotic acid = An acid which donates 100._____
protons. ex: H2S
• 101.__________ acid = Donates 3 protons. ex: H3P
Acid Theories
• 102.______________: A chemical compound
which will increase the concentration of hydrogen
ions (H+) in aqueous solution.
• Bronsted-Lowry acid: Molecules or ions which
act as 103.______________ _____________.
– Although a single proton is a hydrogen ion, most
Arrhenius acids will form the hydronium ion (H3O+)
when dissolved in aqueous solution as a water
molecule “picks up” the free 104.___________ ion.
– Not all Arrhenius acids are 105.____________ acids.
– There are other acid/base theories (106.__________)
Arrhenius Reaction
HNO3 + H2O  H3O+ (hydronium) + NO3• 107.____________ (H3O+) = H2O + H+
• Hydrogen ions form hydronium in aqueous
solution.
Bronsted-Lowry Reaction
HCl + NH3  Cl- + NH4+
• Hydrogen from 108._______was donated to NH3
to form 109._______________________.
1.
2.
3.
4.
5.
Properties of Bases
109.__________ Taste.
110.___________ turn red litmus blue.
Bases have a 111.________ feel. (soaps are
weak bases)
Bases 112.__________ acids producing salt
and water.
Bases are 113._____________________.
–
The term 114.________________ is used to
describe a base or a basic solution.
•
•
•
•
Base Theories
115.____________ base: A compound which
donates hydroxide (OH-) ions when dissolved in
aqueous solution.
NaOH  Na+ + OHNaOH donates OH- in solution and is an
Arrhenius base.
Bronsted-Lowry base: A molecule or ion which
acts as a 116._______________ ___________.
HCl + NH3  Cl- + NH4+
117.________ is a Bronsted-Lowry base as it
accepts a proton (H+) from HCl.
• Base strength is determined by the extent to
which a base ionizes in 118._____ solution.
• 119._________ bases are strong electrolytes.
• Weak bases are weak electrolytes.
• A 120._______________________ (as shown
on the previous slide) contains a BronstedLowry acid (HCl = proton donor) and a BronstedLowry base (NH3 = proton acceptor).
• 127.___________________: Any species
(compound) which can act as either an acid or a
base.
Example of an Amphoteric Compound
• In the following reactions, 123.____________ is
amphoteric. H2O acts as a B-L base in the 1st
equation and acts as a BL acid in the 2nd
equation.
• H2SO4 + H2O  H3O+ + SO4– H2O accepts a 124.__________________ and
therefore acts as a B-L base.
• NH3 + H2O  NH4+ + OH– H2O acts as a proton 125._____________ and
therefore acts as a
B-L acid.
Conjugate Acids and Bases (see pg 469-470)
• 126.__________ ____: The species (compound/ion)
which remains after a Bronsted-Lowry base reacts.
• 127.___________ _______: The species
(compound/ion) which remains after a Bronsted-Lowry
acid reacts.
HCl + NH3  Cl- + NH4+
• In the above reaction, HCl is a B-L acid (proton donor)
and NH3 is a B-L base (proton acceptor)
• Since Cl- remains after HCl donates its proton, Cl- is a
conjugate base.
• Since NH4+ remains after 128.______ accepts a proton,
NH4+ is a conjugate acid.
•
•
•
•
Neutralization
All acid/base 129.______________ have the
same basic general equation as follows:
Acid + base  salt + water
Example: HCl + NaOH  NaCl + H2O
During neutralization 130.______ from the acid
form a bond with hydroxide from the base to
produce water.
The 131.________________ from the acid forms
a bond with the cation from the base to form a
salt.
• 132._____________: The ionic compound which
forms from an acid/base neutralization reaction.
• Indicators: Substances which change color in
the presence of an 133.________ _____ ____.
• pH paper, phenolphthalein, methyl red, and
bromethyl green are common indicators.
• 134________________: the controlled addition
and measurement of the amount of a solution of
known concentration required to react
completely with a measured amount of solution
of unknown concentration.
• Titration allows you to determine the
concentration of an unknown 135._____ __
_______ solution. (see the titration on pages
500-502)
• Titration requires an 136.________________.
• At the 137.__________ _________ in a
titration, the acid and base are present in
chemically 138._________ amounts. (they have
neutralized each other)
• The 139.__________ in a titration is the point in
which the 140.__________ changes color. (see
pg 498)
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