Transcript ch 14-solutions

CHAPTER 14
SOLUTIONS
And
Mixtures
• Immiscible = 2 liquids that can be mixed
but separate shortly after you stop mixing
(oil and vinegar)
• Miscible = two liquids that are soluble in
each other (water and antifreeze)
• Soluble = if a substance dissolves in a
solvent (homogeneous)
• Insoluble = doesn’t dissolve
(heterogeneous)
Mixtures: Heterogeneous
• Heterogeneous Mixture: two or more
substances physically combined, but is not
uniform throughout
– Suspension: mixture that contains large
particles that will settle out if left undisturbed
(oil/vinegar)-can be filtered
– Colloid: mixture of intermediate sized particles
that will not settle out (like milk, blood)-can’t
be filtered
– Both disperse light in Tyndell effect
Types of Colloids
• Gas dispersed in liquid- foam (whipped
cream)
• Liquid dispersed in gas (fogs-mist), Liquid
dispersed in liquid (emulsion-milk,
mayo,blood)
• Solid dispersed in gas (smokes), liquid
dispersed in liquid (gelatin)
Tyndell effect (light is reflected off
the particles in the mixture)
Mixtures: SOLUTION
• DEF = homogeneous mixture containing
two or more substances , uniform
throughout (solute dissolved in a solvent)
• Solvation = the
•
•
process of
surrounding solute
particles with solvent
particles to form a
solution
Video
“like dissolves like”
TYPES OF SOLUTIONS
•
•
•
•
GAS IN GAS =
AIR
GAS IN LIQUID = SODA
LIQUID IN GAS= humid air
LIQUID IN LIQUID =ANTIFREEZE
(ethylene glycol/water)
VINEGAR
(acetic acid/water)
• SOLID IN LIQUID= OCEAN WATER (salt/water)
• LIQUID IN SOLID= DENTAL FILLING(Ag in Hg)
• SOLID IN SOLID= STEEL (Fe in Carbon)
• GAS IN A SOLID – pop rocks (mythbuster) (spangler)
SOLUBILITY
• Def= the maximum amount of solute that
will dissolve in a given amount of solvent
at a specific temperature and pressure
• Three types of solutions:
– Saturated
– Unsaturated
– supersaturated
SATURATED SOLUTION
• Contains the maximum amount of
dissolved solute for a given amount of
solvent
UNSATURATED SOLUTION
• Contains less dissolved solute than a
saturated solution (more solute can still be
dissolved)
SUPERSATURATED SOLUTION
• Contains more solute than a saturated
solution, made by increasing the
temperature and allowing the solution to
cool slowly
• Very unstable
• Example: rock candy
SEEDING IN A SUPERSATURATED SOLUTION
Sodium acetate seeding
Sodium acetate sculptures
• For those about to dissolve, we solute you
FACTORS AFFECTING SOLUBILITY
• TEMPERATURE- as temperature increases
the solubility of a gas solute decreases
– Note: most solids increase in solubility w/an
increase in temperature
• PRESSURE- the solubility of a gas in a
solvent increases as it’s external pressure
increases
– ex: fizz keeper/soda
•
•
•
•
•
Mentos and diet soda
Experiment 2- domino effect
Mythbusters explain
Merry Blastmus (mythbusters)
Why?: It’s a process called "nucleation," in which the
particular chemistry of the Mentos candy (mint kind, notglazed) interacts with the chemistry of the carbonated
Diet Coke, causing the carbon dioxide gas, or CO2, to
suddenly come out of suspension in the liquid and make
a break for freedom. (diet coke instead of regular- no
sugary mess for the ants will be left behind)
MOLARITY (M)
• Def = concentration of a substance
• Used to express the ratio between solute
and solvent
• Specifically, molarity is the ratio between:
Moles of solute
Liters of solvent
M=
moles
liters
Remember: 1000ml = 1 L = 1000cm3 = 1 dm3
• 1. Grams to Molarity
What is the molarity of a solution if you
dissolved 35.2 g of NaCl in 500.0 ml of
H2O?
Steps:
1. first find molar mass of solute:
NaCl = 58.5 g/mole
2. Convert grams to moles
35.2 g NaCl
1 mole NaCl
58.5 g NaCl
3. use M = mole/liter
M = .602 mole
.5000 L
.602 mol
(convert if needed)
= 1.20 M or 1.20 mole/liter
• 2. Molarity to grams
How many grams of KBr do you need to
make 250 ml of a 0.725 M solution?
Steps:
1. convert molarity to moles
M = mole
liter
.725 M = mole
.25 L
= .18 moles
• 2. convert moles to grams (molar mass of
KBr = 119.1 g/mole)
.18 mole
119.1 g
1 mole
= 21 g
PREPARING SOLUTIONS
• 1. Going from molarity to grams (review)
How many grams of CaCl2 would be
dissolved in 1.0 L of a 0.10 M solution?
M = mole
liter
.10 M = mol =
1.0 L
.10 mol
111.1 g
1 mol
.10 mol
= 11 g
• 2. DILUTION: using concentrated stock
solutions and diluting them down to other
concentration needed
• The total number of moles does NOT
change during dilution
• M = mole/V
• moles (concentrate) = M1V1
• moles (dilute) = M2V2
• Moles concentrate =moles diluted
Dilution formula
So
M1V1 = M2V2
• What volume of a 3.00 M KI solution would you
•
need to make 0.300 L of a 1.25 M KI solution?
V1 = ?
V2 = .300 L
M1V1 = M2V2
M1 = 3.00 M
M2 = 1.25 M
(3.00 M)(V1) = (1.25 M)(.300 L)
V1 = (1.25 M) (.300 L)
3.00 M
= 0.125 L OF 3.00 M KI
So: You would add .125 L of 3.00M KI to .175 L of
water to make a 1.25 M solution
FREEZING POINT DEPRESSION
• As a pure solvent reaches freezing point,
the molecules KE slows down and the
attractive forces between particles take
over
– It freezes
BUT……..
• When a solute is mixed in, the solute particles
interfere w/the attractive forces, preventing the
solvent from freezing at its normal point (lowers
the freezing point)
• FREEZING POINT DEPRESSION = the difference
in temp. between a solution’s freezing point and
the freezing point of the pure solvent
• Simulation
• http://www.worsleyschool.net/science/files/saltandfreezing/ofwater.
html
• Types of road salt
• Making Ice Cream (spangler)
How its made- ice cream treats
• http://www.youtube.com/watch?v=SiICaH
AOrGE
BOILING POINT ELEVATION
• When a pure solvent reaches its boiling
point it has enough kinetic energy to
break free from the attractive forces and
atmospheric pressure
• BUT….when a solute is added to the
solution it must be heated to a higher
temp. to supply the additional kinetic
energy for the solution to boil
• BOILING POINT ELEVATION = the temp.
difference between a solution’s boiling
point and a pure solvent’s boiling pt.
• Simulation
Quest
• 12 multiple choice/short answer
– Know vocab
– Solution types
– Ways to increase/decrease solubility
• 4 calculations
– Grams to molarity
– Molarity to grams
– Dilution
– Formulas/periodic table will be given
Song- For those about to
dissolve- we solute you
• Review quiz
• Hangman
• Jeopardy