Transcript Unit 8 - Solution and Solubility

How can we describe solutions?
How can we explain molecule-ion
attraction in an aqueous solution?
How can we use Table G to understand
solubility curves?
How can we use Table F to predict
solubility and the products of double
replacement reactions?
What are the factors that affect
solubility?
What are the factors that affect the rate
of dissolving?
What are colligative properties and how
do electrolytes affect them?
How can we determine the
concentration of solutions?
TOPIC 8:
SOLUTIONS
AND SOLUBILITY
-
HONORS CHEMISTRY
Ms. Argenzio
AIM: How can we describe
solutions?
~~~~Homogenous Mixtures aka – SOLUTIONS~~~~

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


Solutions are homogeneous
Dissolved particles will not come out of the solution
no matter how long its stands unless temperature
changes or evaporation occurs
Liquid and gas solutions are clear and transparent
(dissolved particles cannot be seen)
Cannot be filtered
Single phased even though the components that
make it up can be of different phases
AIM: How can we describe
solutions?
PARTS OF A SOLUTION
 Solutions
consist of solute and solvent
(solution = solute + solvent )
 Solute
– dissolved substance (smaller portion of
solution)
 Solvent
– substance in which the solute is
dissolved (the larger portion of the solution)
AIM: How can we describe
solutions?
TYPES OF SOLUTIONS
 Gas solutions – (air) gases have completely dissolved
in one another

Liquid Solutions – Consist of a solute which can be a
solid, liquid, or gas dissolved in a solvent Ex:
 Carbonated water – CO2 gas in water
 Salt water – solid in water
 Antifreeze – ethylene glycol

Solid Solution – mostly solid dissolved in solid. It can
also be a liquid or gas dissolved in a solid Ex:
 Alloys Brass – Cu/Zn

Bronze Cu/Sn
AIM: How can we describe
solutions?
Homogeneous aka
solutions/miscible
(capable of being mixed)

A solution is
produced when
one substance
dissolves in another

Salts are ionic
Heterogeneous
mixture –
nonuniform/immiscible
 Heterogeneous
mixtures are
immiscible. They
do not mix and do
not dissolve
Saturated Solutions are in Equilibrium
AIM: How can we explain
molecule-ion forces of
attraction in an aqueous
solution ?
Molecule ion attraction :
Mixing ionic compounds
with water form aqueous
solutions of dissolved ions
Polar water molecules
attract to the ions tearing
them apart from the
other ions
Crystal salt dropped in
H 2O
AIM: How can we explain
molecule-ion forces of
attraction in an aqueous
solution ?
http://www.youtube.com/watch?v=xd
edxfhcpWo&feature=related
http://www.youtube.com/watch?v=7P
HhBBg-6X0&feature=related
AIM: How can we describe
solutions?

Saturated: has the maximum amount of solute
dissolved in them. No more solute can be made to
dissolve (100 seat restaurant with 100 people in it)

Unsaturated: has less than the maximum amount of
solute dissolved in them. This means that more solute
can be added to the solution and the additional
solute would still dissolve( 100 seat restaurant with 40
people in it)

Supersaturated: Rare solution where the solution
holds more solute than is theoretically possible,
unstable where the excess will precipitate if the
solution is agitated (100 seat restaurant with 120
people in it, then the manager comes in, he throws
the extra 20 people out)
AIM: How can we describe
solutions?
 Using
reference Table G!!!!!
 Up curves represent salts
(direct relationship: increase T, increase solubility)
 Down curves represent gases
(indirect relationship: increase T, decrease solubility )
AIM: How can we understand
solubility curves?
 Each
line represents a saturated solution of a solute
at different temperatures
 Higher a line is at a given temperature the more
soluble that substance is
 Data tells us how many grams of solute can be
dissolved in 100g of water a particular temperature
AIM: How can we understand
solubility curves?
Any point on line represents
a saturated solution.
Saturated solutions are at
equilibrium
 Rate of dissolution is
equal to the rate of
crystallization
AIM: How can we use Table F
to predict solubility?
 View
video on Solutions and Solubility:
http://www.youtube.com/watch?v=VTmfQ
UNLlMY
AIM: How can we use Table F
to predict solubility?
 Table
F gives us information on the
solubility of various compounds in solutions
 You
can predict the solubility of a
compound or the two products in a
double replacement reaction
AIM: How can we use Table F
to predict solubility?
 DIRECTIONS:
1.
2.
3.
Cross out the symbol of the first ion or
element
Underline the symbol of the second ion
or element
Use TABLE F to predict solubility
AIM: How can we use Table F
to predict solubility?
 EXAMPLE:
AIM: How can we understand
and recognize double
replacement reaction?
 Double
reactions contains 2 ionic compounds
 Every double replacement reaction will not
necessarily occur. There are 3 situations that
ensure a DR occurs:
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
If one of the products is a solid
One of the products is a gas
A molecular substance such as water is formed
AIM: How can we predict the
products and solubility of the
products of DR reactions?
KI + Pb(NO3)2  _________ + ______________
1.
2.
Predict products – the reactants swap places
Determine solubility of products
EXAMPLE: For the reaction between LiBr and BaNO3
predict the products and determine the solubility
of the products
“If you are not part of the solution
you are part of the precipitate”
 Precipitate
– insoluble solid (cant be dissolved)
 Table
F–
SOLUBLE – dissolved
INSOLUBLE – not dissolved
*right side of the table all insoluble and they all have
exceptions
2/11/13 – D day
AIM: How can we use Table F and G?
DO NOW: Answer the Following Questions:
1. Identify the solute and solvent in air

2. If 106g of KNO3 are added to 100g H2O at 60C, what kind
of solution is formed?
3. If 110g of KNO3 are added to 100g H2O at 50C, what kind
of solution is formed?
4. If 60g of KNO3 are added to 100g of water at 50C, what
kind of solution is formed? How can you make this solution
saturated?
5. If 110g of KNO3 are dissolved in 100g of H2O at 62C, what
kind of solution is formed? How can you make this solution
saturated?
AIM: What are some factors
that affect solubility?
 Solubility:
how much solute is dissolved in
a given amount of solvent
 Solubility
is measured in grams of solute
per 100 grams of solvent (mostly water)
 Solubility must always be accompanied
by a temperature
NaCl 36g/100g H2O @ 25C
AIM: What are some factors
that affect solubility?
FACTORS THAT AFFECT SOLUBILTY:
 Nature
of the solute
 Temperature
 Pressure
Nature of the Solute
 All
solute don’t dissolve to the same
extent in H2O
Examples:
PbCl2 1g/100g H2O @ 25C
ZnCl2 200g/100g H2O @ 25C
TEMPERATURE
 Solid
Solutes – as T increases, Solubility increases
 Liquid Solutes – as T increases, Solubility increases
 Gas Solutes – as T increases, Solubility decreases
PRESSURE
 Solid
Solutes – as P increases, no effect
 Liquid Solutes – as P increases, no effect
 Gas Solutes – as P increases, Solubility increases
Applying the principles
of solubility and
pressure, explain why
soda goes flat when
you open the can.
3/25/14 – A day
AIM: Factors affecting dissolving rate?
DO NOW: Answer the Following Questions:
1. Identify the solute and solvent in air

2. If 106g of KNO3 are added to 100g H2O at 60C, what kind
of solution is formed?
3. If 110g of KNO3 are added to 100g H2O at 50C, what kind
of solution is formed?
4. If 60g of KNO3 are added to 100g of water at 50C, what
kind of solution is formed? How can you make this solution
saturated?
5. If 110g of KNO3 are dissolved in 100g of H2O at 62C, what
kind of solution is formed? How can you make this solution
saturated?
AIM: What are some factors
that affect the Rate of
Dissolving?
 Size
of the particles – smaller particles
dissolve faster than larger particles
 Stirring – increase the stirring, increase the
rate of dissolving
 Temperature – increase the temperature,
increase the rate of dissolving
 Nature of the solute and solvent – “LIKE
DISSOLVES LIKE RULE”
AIM: What are some factors
that affect solubility?
LIKE DISSOLVES LIKE RULE
 Like
polarities will dissolve in like polarities
 Polars will attract polars (like), and repel
non-polars (opposites). Non-polars will
attract non-polars (like), and repel polars
(opposites)
 Oil, which is non-polar, does not mix with
water, which is polar (opposites repel)
AIM: What are some factors
that affect solubility?
Critical thinking:
A student was working in a lab. Grease
spilled all over his hands. He went to the sink
to clean his hands. The grease, which was
non polar, did not come off. Once the
student used soap and water, all of the
grease came off. EXPLAIN
AIM: What are colligative
properties ?
Colligative property  physical properties of
solutions that depend on the concentration of
solute in a given amount of solvent
When any pure solvent forms a solution two things
occur:
1. Boiling point elevation
2. Freezing point depression
AIM: How do electrolytes and
non electrolytes affect the
boiling point and freezing
point of solutions?
•
Summary – the measure of
changes in boiling point and
freezing point are
dependent on:
-Solute (electrolyte vs.
nonelectrolyte)
-Number of particles in solution
-Concentration
NOTE: The addition of
electrolytes and non
electrolytes will raise the
boiling point and lower
the freezing point of a
solution. However, the
electrolyte will have a
greater effect
AIM: What are electrolytes
and how do they behave?
ELECTROLYTES
 Ionic substances (salts)
 Acids (HX)
 Bases (MOH)
NON-ELECTROLYTE
 Sugars (C6H12O6)
 Alcohols R-OH
Summary
• Electrolytes conduct and turn a light bulb tester on. When placed
in aqueous solutions electrolytes dissociate, ionize or break apart
• None electrolytes do not conduct and will not turn on a light bulb
tester. When placed in water non-electrolytes do not dissociate,
ionize or break apart
Exercise: Determine if the following
are electrolytes or non-electrolytes
and sub classify
E or NE
HCl
C6H12O6
NaOH
CH3OH
ZnCl2
Acid
Base
Ionic/Salt
EXCEPTIONS
ACID
 CH3COOH
BASE
= HX
Although acetic acid
or vinegar does not
look like HX, it is still
an acid – exception!
 NH4OH
= MOH
Although ammonium
hydroxide does not
look like MOH, it is still
a base – exception!
AIM: How can we determine the
concentration of solutions?
Concentration: the amount of the solute
dissolved in the solution.
For solutions there are several ways to express
concentration :
1. Grams of solute/100mL of solvent (TABLE G)
2. Molarity
3. Parts per million
4. % by mass
5. % by volume
AIM: How can we determine the
molarity of solutions?
 Molarity
(M) – the number of moles of
solute (n) divided by the volume (V) of the
solution in liters
**important to note that molarity is not
moles of solute per liter of solvent !!
Percent by Mass
 Labels
often list the concentration of the
ingredients as a percent by mass. Fertilizers list
the active ingredients as a percentage of the
entire mass of fertilizer
 Percent
by mass – the mass of the part divided
by the mass of the whole solution
 EX:
What is the percent by mass of sodium
hydroxide if 5.00g of NaOH are added to 50.00g
of H2O?
Percent by Volume

Percent by volume – used when
two liquids are mixed to form a
solution

A label on a bottle of alcohol
shows a common example

% by volume is the ratio of the
volume of an ingredient divided
by the total volume and
expressed as a percent

EX: What is the percent by
volume of alcohol if 50mL of
ethanol is diluted with water to
form a total volume of 3000mL
How can we understand what
parts per million means?
 If
you divide a pie equally into 10 pieces,
each piece would be a part-per-ten; i.e.,
one-tenth of the total pie
 If
you cut this pie into a million pieces,
each piece would be very small and
would represent a millionth , or part per
million, of the original pie
How can we determine
concentration of a solution in
parts per million?
 Parts
per million is the ratio between the
mass of the solute and the total mass of
solution
 This
method is useful for extremely dilute
solutions when molarity and percent mass
would be too difficult to interpret
Questions:
 Carbon
dioxide has a solubility of
0.0972g/100g H2O @40dC. Expressed in
parts per million this concentration is
closest to what value?
A
substance has a solubility of 350ppm.
How many grams of the substance are
present in 1.0L of a saturated solution?