starter s-161 define a.saturated solution b.miscible c.supersaturated solution
TRANSCRIPT
Starter S-161
Define
A. Saturated solution
B. Miscible
C. Supersaturated solution
Solutions
Chapter 16
16.1 Properties of Solutions
Chapter 16
Solutions occur when a solute dissolves in a solvent
Solutions are homogeneous mixtures
Three factors determine how rapidly solutes dissolve
16.1 Solution Properties
Sink Hole
Animation
1. Stirring – moves fresh solvent over the surface of the solute
2. Temperature – particles move faster at higher temperatures, increase in frequency and force of collisions between solute and solvent
3. Particle Size – smaller particles expose greater surface areas to the colliding solvent
16.1 Solution Properties
Solubility – the amount of solute dissolved in a given amount of solvent
Unsaturated – more
solute can be
dissolved at a
specific temp
Saturated – maximum
solute that can
be dissolved
16.1 Solution Properties
Some liquids are infinitely soluble in each other.
They are said to be miscible.
Immiscible – liquids that are insoluble in each other
Solubility is often given as
grams of solute per 100g of
solvent
16.1 Solution Properties
immiscible
A solubility curve gives the solubility (usually in grams solute per 100g solution) as it varies with temperature
For most substances solubility increases with temperature
Charts are for specific solvents
You will need to read these charts for the test
16.1 Solution Properties
Pressure has little effect on the solubility of liquids or solids
Strong effect on the solubility of gases
Henry’s Law – at a certain
temperature, the
solubility of a gas in
a liquid is proportional
to the pressure of the
gas above the liquid
16.1 Solution Properties
2
2
1
1
P
S
P
S
16.2 Concentrations of Solutions
Chapter 16
There are different ways to calculate how much solute is dissolved
Concentration – the amount of solute dissolved in a solvent
Dilute – small amount
of solute
Concentrated – large
amount of solute
16.2 Concentrations of Solutions
Molarity (M) – the number of moles of solute dissolved in one liter of solution
Moles are calculated from the mass
Volume must be in liters (convert from mL if necessary)
Volume is the total final volume of the solution, not the volume of the solvent
16.2 Concentrations of Solutions
V
nM
Example: 0.90g NaCl is dissolved to make 100.0 mL of solution. What is the molarity of the soution?
16.2 Concentrations of Solutions
V
nM
gggmassmolar 5.58)5.35()0.23(.
molg
molgNaCln 0154.0
5.58
190.0
V
molM
0154.0
LmL
LmLV 1000.0
1000
10.100
L
molM
1000.0
0154.0 MM 15.0
Example: Household laundry bleach is a dilute aqueous solution of sodium hypochlorite. How many moles of solute are present in 1.5 L of 0.70M NaClO?
16.2 Concentrations of Solutions
V
nM MVn )5.1)(070(. LMn moln 05.1 moln 0.1
Often it is necessary to dilute a chemical.
Make it’s molarity lower
However, we can not reduce the number of moles in solution without a chemical reaction
16.2 Concentrations of Solutions
V
nM MVn 2211 VMnVM 2211 VMVM
Example: How many milliliters of aqueous 2.00M Magnesium Sulfate must be diluted with water to prepare 100.0 mL of 0.400 M Mangesium Sulfate?
This means that 20.0 mL of the 2.00 M solution must be mixed with 80.0 mL of water (the solvent) to make the 0.400 M solution
16.2 Concentrations of Solutions
)0.100)(400.0()00.2( 1 mLMVM 2211 VMVM mLV 0.201
Percent Solutions – can be expressed two ways
Percent by mass
16.2 Concentrations of Solutions
%100.
.% x
solutionmass
solutemassm
Example: How many grams of glucose is needed to make 2000.0g of a 2.8% by mass solution?
16.2 Concentrations of Solutions
%100.
.% x
solutionmass
solutemassm %100
0.2000
.%8.2 x
g
solutemass
g
solutemass
0.2000
.028.0 gsolutemass 56.
Percent Solutions – can be expressed two ways
Percent by mass
It helps often to remember that 1g of water equals 1 mL of water
16.2 Concentrations of Solutions
%100.
.% x
solutionvolume
solutevolumeV
Example: What is the percent volume of ethanol (C2H6O) in the final solution when 85 mL of ethanol is diluted by adding 165 mL of water?
16.2 Concentrations of Solutions
%100.
.% x
solutionvolume
solutevolumeV %100
)16585(
)85(% x
mLmL
mLV
%100)250(
)85(% x
mL
mLV %10034.0% xV %34% V
16.3 Colligative Properties of Solutions
Chapter 16
Colligative Property – depends only on the number of solute particles, not their identity
1. Vapor-Pressure Depression (lowering)
2. Boiling-Point Elevation (increasing)
3. Freezing-Point Depression
16.2 Concentrations of Solutions
Vapor-Pressure Depression
The surface of a liquid has particles that are constantly leaving the surface and some particles returning (equilibrium)
16.2 Concentrations of Solutions
Vapor-Pressure Depression
If a solute is dissolved in the solvent
Not as many molecules can escape the surface
16.2 Concentrations of Solutions
Vapor-Pressure Depression
This reduces the amount of gas above the solution
So the vapor pressure decreases
16.2 Concentrations of Solutions
Vapor-Pressure Depression
The decrease in a solution’s vapor pressure is proportional to the number of particles the solute makes in solution
16.2 Concentrations of Solutions
Freezing-Point Depression
When a substance freezes the particles take on an orderly pattern
The addition of a solute
disrupts this pattern
More kinetic energy must be
withdrawn form the
solution to cause it to solidify
16.2 Concentrations of Solutions
Freezing-Point Depression
The difference in temperature between the normal freezing point of the solvent and the freezing point of the solution is called freezing-point depression
16.2 Concentrations of Solutions
Freezing-Point Depression
Salt is added to ice to lower the freezing point
If enough salt it added, the freezing point is depressed and the ice turns to liquid
16.2 Concentrations of Solutions
Boiling Point Elevation
Boiling occurs when the vapor pressure of the liquid equals the atmospheric pressure
Solutes decrease vapor pressure, so a solution must be at a higher temperature before it can boil
16.2 Concentrations of Solutions
Boiling Point Elevation
The difference between the normal boiling point of the solvent and the boiling point of the solution is called boiling point elevation
16.2 Concentrations of Solutions
Remember that all colligative properties are proportional to the number of particles in solution
The greatest effect would occur in a 50/50 solutions
Antifreeze is mixed withwater to increasethe boiling point andto lower the freezingpoint
16.2 Concentrations of Solutions