1. Solutions

2. 13.1 What is Solution?
A solution is a stable homogeneous mixture of two or more substances uniformly dispersed throughout a single phase
Mixtures can either be heterogeneous or homogeneous.
The particles of a heterogeneous mixture are large enough
In a homogeneous mixture, however, the particles are molecule-sized, so the mixture appears uniform, evenly mixed

3. Suspensions are temporary!
A suspension is a mixture in which particles of a material are more or less evenly dispersed throughout a liquid or gas.

4. Solutions are stable homogenous mixtures

5. Solution is a broad term
Solvent – Dissolving Medium (larger amount)
Solutes – dissolved particles (smaller amount)
Water is the most common solvent.
Water is a unique solvent because so many substances can dissolve in it.
Solutions in which water is the solvent are called aqueous solutions.

6. Solid + Solid = Solution
Another type of solution involves one solid mixed with another solid.
Examples include solid alloys, such as brass, bronze, and steel.

7. Colloids are stable heterogeneous mixture
Heterogeneous mixtures
not the same throughout
Suspensions
Mixture that eventually settles out (ex. Italian dressing)
Colloid
Mixture that does not settle out; particles are dispersed throughout the mixture (ex. milk)

8. 13.2 Concentration and molarity
a measure of the amount of solute dissolved in a given quantity of solvent
A concentrated solution has a large amount of solute
A dilute solution has a small amount of solute

9. Parts Per Million (ppm)
Number of grams of solute in 1 million gram of solvent
One unit of concentration used in pollution measurements that involve very low concentration

10. A chemical analysis shows that there are 2
A chemical analysis shows that there are 2.2 mg of lead in exactly 500 g of water. Convert this measurement to parts per million.
parts solute
mass of solute: 2.2 mg
mass of solvent: 500 g
parts per million = ?
= ppm
1 million solvent
2.2 mg
1 g
= 2.2 x 10-3 g
1000 mg
2.2 x 10-3 g
1,000,000 parts
= 4.4 ppm
500 g
1 million

11. Helium gas, 3. 0 x 10-4 g is dissolved in 200. 0g of water
Helium gas, 3.0 x 10-4 g is dissolved in 200.0g of water. Express this concentration in ppm.
parts solute
mass of solute: 3.0 x 10-4 g
mass of solvent: g
parts per million = ?
= ppm
1 million solvent
1,000,000 parts
3.0 x 10-4 g
= 1.5ppm
200 g
1 million

12. % Composition by mass g of solute x 100 % % Composition =
g of solution
What is the percentage by mass of a solution made by dissolving 0.49 g of potassium sulfate in g of water? =
0.49 K2SO4
12.70g water

13. What is the percentage concentration of 75
What is the percentage concentration of 75.0 g of ethanol dissolved in g of water?
g of solute
x 100 %
% Composition =
g of solution
75.O g of ethanol
x 100 %
500g water g of ethanol
=13.0 %
75.0 g ethanol
500g water

14. Molarity (M)
Molarity (M) is a concentration unit of a solution expressed as moles of solute dissolved per liter of solution.

15. What is the molarity of a potassium chloride solution that has a volume of mL and contains 85.0 g KCl?
1 mol KCl
solute = 85 g KCl
= 1.14 mol KCl
74.55 g KCl
solution = 400 mL
1 L
= 0.4 L
1000 mL
= 2.85 M

16. An aqueous solution of sodium carbonate, Na2CO3, contains 53 g of solute in 215 mL of solution. What is it concentration (M)?
1 mol Na2CO3
solute = 53 g Na2CO3
= 0.5 mol Na2CO3
g Na2CO3
solution = 215 mL
1 L
= L
1000 mL
= 2.3 M

17. How many moles of sugar are dissolved in 202 mL of a 0. 150 M solution
How many moles of sugar are dissolved in 202 mL of a M solution? How many moles of C12H22O11 is that?
solution = 202 mL
1 L x
= L
1000 mL
Molarity = M
mol = M · L
mol = M · L
= (0.150 mol/L)(0.202 L)
= mol C12H22O11

18. A mass of 98 g of sulfuric acid, H2SO4, is dissolved in water to prepare a 0.50 M solution. What is the volume of the solution in liters ?
1 mol H2SO4
solute = 98 g H2SO4
= 1.0 mol H2SO4
98.08 g H2SO4
solute = 1.0 H2SO4
Molarity = 0.50 M
= 2.0 L H2SO4

19. Determine the moles of copper that will react with 0. 025 L of a 6
Determine the moles of copper that will react with L of a 6.5 M HNO3 solution.
3 Cu (s) + 8 HNO3(aq) → 3 Cu(NO3)2(aq) + 2 NO(g) + 4 H2O(l)
solution = L
Molarity = 6.5 M HNO3
mol = M · L
= (6.5 mol/L)(0.025 L)
= mol HNO3
mol HNO3
3 mol Cu x
= mol Cu
8 mol HNO3

20. What volume (in milliliters) of a 0
What volume (in milliliters) of a M solution of copper(II) sulfate, CuSO4, is needed to react with an excess of aluminum to provide 11.0 g of copper?
3CuSO4(aq) + 2Al(s) → 3Cu(s) + Al2(SO4)3(aq)
Solute = 11.0 g Cu
Molarity = M CuSO4
1 mol Cu
solute = 11 g Cu
= 0.17 mol Cu
63.5 g Cu
0.17 mol Cu
3 mol CuSO4 x
= mol CuSO4
3 mol Cu
L = mol / M
= (0.17 mol)/(0.500 mol/L)
= 0.34 L CuSO4 = 340mL

21. Molality (m or molal)
solute in moles and the mass of solvent in kilograms;
1 L = 1 Kg g = 1 Kg
1 mL = 1 g

22. What is the molality of a solution with 9
What is the molality of a solution with 9.3 mole of NaCl in 450 g of water?
Mols of solute = 9.3 mol
Kg of solvent = 450 g = 0.45 Kg
9.3 mol
= 21 m
0.45 Kg

23. Determine the molality of a solution of 560
Determine the molality of a solution of 560. g of acetone, CH3COCH3, in 620 g of water.
Mols of solute = 560g x (1 mol/58.09 g ) = 9.6 mol
Kg of solvent = 620 g = 0.62 Kg
9.6 mol
= 15.5 m
0.62 Kg

25. 13.3 Solubility and Dissolving Process
Solubility is the ability of one substance to dissolve into another at a given temperature and pressure
“Like dissolves Like”
Polar compounds dissolve in other polar compounds,
nonpolar compounds dissolve in other nonpolar compounds.
Ex: Oil (nonpolar) + Water (polar) = no solubility
Ex: Salt (ionic/Polar) + Water (Polar) = solubility
Ex: hydrocarbon(nonpolar)+ paint thinner(nonpolar) = soluable

26. Miscible vs. Immiscible
liquids that are completely soluble with each other are described as being miscible in each other.
The two liquids that do not mix are immiscible.
The immiscible liquids form two layers.
The polar water molecules attract each other, so they cannot be pushed apart by the nonpolar oil molecules to form a solution.

27. Water is a polar solvent, while hexane is a nonpolar solvent.
Which of the examples above illustrates a nonpolar solute in a polar solvent?
NH4Cl in water
C10H8 in water
C2H5OH in hexane
CO(NH2) 2 in hexane
Solute
Water
Hexane
NH4Cl, ammonium chloride
Soluble
Insoluble
C10H8, naphthalene
C2H5OH, ethanol
CO(NH2)2, urea

28. Solubilities of Solid Compounds
To speed up the solubility
Increase the surface area, by breaking into smaller pieces
Molecules are dissolved faster when they are apart (ex: sugar cube vs. sugar granule)
Agitation
Stirring or shaking
moves fresh solvent next to the solute thus increasing the rate
Increase temperature
solvent molecules with greater kinetic energy can dissolve more solute particles

29. Enthalpy and entropy affect solubility of salts
The dissolving of an ionic compound involves a unique factor: the separation of ions from the lattice into individual dissolved ions.
Dissociation is the separating of a molecule into simpler molecules, atoms, radicals, or ions.
Dissociation can be represented as an equation.
NaCl(s) → Na+(aq) + Cl−(aq)
If water is the solvent, above dissociation is called hydration.

30. Saturation of Solutions
A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated.
A solution that contains less solute than a saturated solution under existing conditions is unsaturated.
A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.

31. no more solute dissolves SUPERSATURATED SOLUTION
UNSATURATED SOLUTION
more solute dissolves
SATURATED SOLUTION
no more solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration

32. Cloud seeding
Ever heard of seeding the clouds to make them produce rain?
Clouds- mass of air supersaturated with water vapor
Silver Iodide (AgI) crystals are dusted into the cloud
The AgI attracts the water, forming droplets to attract others

33. What happens if 46.4 g NaCH3COO added to 100. g of 20ºC water?
It all dissolves
What happens if add 46.5 g?
Mostly dissolves
Would stirring help dissolve more?
No! It only makes what will dissolve do so faster

34. Solubility Equilibrium
In a saturated solution, the solute is recrystallizing at the same rate that it is dissolving.
When the amount of solute added to a solvent has reached its solubility limit, it is at equilibrium
Solubility equilibrium is the physical state in which the opposing processes of dissolution and crystallization of a solute occur at equal rates.

35. Gases can dissolve in liquids
Gas solubility depends on pressure and temperature
Henry’s law states that the solubility of a gas increases as the partial pressure of the gas on the surface of the liquid increases
Gases are less soluble in a liquid of higher temperature because the increased molecular motion in the solution allows gas molecules to escape their loose association with the solvent molecules
Gas is soluble at LOW temperature, HIGH pressure
SOLUBILITY, COKE

36. The gas is at equilibrium with the dissolved gas in this solution.
The equilibrium is dynamic.
Rf. Fig Z5e 523

37. If you increase the pressure the gas molecules dissolve faster than they escape.
The equilibrium is disturbed.

38. The system reaches a new equilibrium with more gas dissolved.
Henry’s Law. P= kC
Pressure =
constant x Concentration of gas
Henry’s Law: Gas solubility in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.
Hrw 407

39. Solubility overview
For gases in a liquid, as the pressure goes up-the solubility goes up
For gases in a liquid, as the temperature goes up-the solubility goes down
For solids in liquids, as the temperature goes up-the solubility usually goes up

40. 13.4 Physical Properties of Solutions
The conductivity of a substance is described as its ability to conduct an electric current.
Electrolytes- compounds that conduct electricity when molten or dissolved
All ionic compounds (ex. NaCl)
Nonelectrolytes-
Not composed of ionic cmpds (ex. Sucrose)
Weak electrolytes- ex. Acetic acid
Strong electrolytes- ex. NaCl
STRONG vs. WEAK

41. Electrolytes

42. Surfactants Surfactant Soap is an emulsifying agent.
surface active agent
interferes with H-bond, reducing surface tension (Ex: Soaps and detergents)
Long chain of polar and nonpolar
Connects insoluble with water
Soap is an emulsifying agent.
An emulsion is made of colloid-sized droplets suspended in a liquid in which they would ordinarily be insoluble, unless stabilized by an emulsifying agent, such as a soap