1. Solutions

2. Solution = Solvent + Solute
Solvent: a substance that dissolves another substance
Or, the substance present in greater amount
Solute: a substance which is dissolved by another substance
Or, the substance present in lesser amount

3. Copper (II) Sulfate is dissolved in water to form a solution
Copper (II) Sulfate is dissolved in water to form a solution. Which substance is the solvent and which is the solute?

4. Water is sometimes called the “Universal Solvent”
It is the most common solvent in nature/biological systems
Why do you think water is such a good solvent?
Polarity
Hydrogen bonding

5. The positive end of water molecules are attracted to the negative part(s) of the solute
The negative end of water molecules are attracted to the positive part(s) of the solute
The attraction of water molecules to different parts of a solute is enough to break the solute apart

6. As each ion in the solute is drawn into solution, it is surrounded by water molecules
This process is called “solvation”
Solvation lessens the attraction of the solute ions to each other

7. If water is the universal solvent, then why does it not dissolve oil?
For a solution to form, the solvent and solute molecules must be attracted to each other
“Like Dissolves Like”
Polar solvents dissolve polar solutes
Nonpolar substances are attracted to other nonpolar substances, therefore nonpolar solvents will dissolve nonpolar solutes
Examples: I2, Hexane, Cooking Oils

9. Problems
Identify the solute and solvent in solutions composed of the following:
2.9g of NaCl and 200g H2O
25.0mL of ethanol (a liquid) and 20.0mL H2O
2.0g I2 and 20g Octane
Look at the pictures below. Explain why each substance will or will not dissolve in water.

10. Solubility
Solubility: the amount of solute that will dissolve in a specific solvent under given conditions
Polar solutes will be more soluble in polar solvents
Non-polar solutes will be more soluble in non-polar solvents
Amphiphilic solutes will be soluble in both polar and non-polar solvents
Have hydrophobic and hydrophilic regions
Example: Phospholipids

11. Solubility is expressed in g solute/100g solvent
Example: The solubility of Ethanol is 10g/100g 23ºC
Unsaturated Solution: solution in which the solvent can dissolve more solute
Saturated Solution: solution in which the solvent cannot dissolve any more solute

12. When a solution is saturated, the rate of dissolution is the same as the rate of recrystallization/precipitation

13. Say we have a saturated sugar solution
Say we have a saturated sugar solution. How might we get even more sugar into the solution?
Heat it!
Solubilities of solids generally increase as the temperature increases

14. Supersaturated solution: an unstable solution which temporarily contains more dissolved solute than a normal saturated solution would at that specified temp

15. What about if you wanted to dissolve more oxygen in your water
What about if you wanted to dissolve more oxygen in your water? Would you heat your water?
No!
The solubility of gases tend to decrease as the temperature is increased

16. So, how do you increase the solubility of gases in a liquid?
Decrease the temperature
Increase the pressure
Henry’s Law: the solubility of a gas in a liquid is directly proportional to the pressure of that gas above the liquid

17. Soluble and Insoluble Salts
How do you know that NaCl is soluble in water?
What about KBr? Is it soluble?
What about AgCl?
You can tell if a salt will be soluble or insoluble in water by looking up the cation and the anion on a solubility chart

19. Problems
Is the CO2,which is dissolved in soda, more or less soluble when you open the can? Why?
Which of the following is probably Ni(OH)2 in water?
Which is most likely Na2SO4 in water?

20. Problems
Which of the following salts is soluble in water? Which is insoluble?
NaCl
KBr
AgCl

21. KBr
NaCl
AgCl

22. Problems Ag2O CdS Fe(OH)2 Na2SO4 KCl
Which of the following salts will be soluble in water? Which will be insoluble?
Ag2O
CdS
Fe(OH)2
Na2SO4
KCl

23. CdS
Ag2O
Fe(OH)2
Na2SO4
KCl

24. Concentrations Concentration = amount solute/amount solution
There are various ways to express concentration
The most common way to express concentration is Molarity (M)
Molarity = moles solute/liters solution
Units: mol/L

25. Problems
You dissolve 5.66g KBr in enough H2O to make 27mL of solution. What is the molarity of your solution?
You dissolve 2.45 mg of CuSO4 in enough water to make 55.5 mL of solution, what is your concentration?
If you have 60.0 mL of a M NaCl solution, how much NaCl did you start with?

26. Mass-volume percent (% m/v): mass of the solute divided by the volume of solution and multiplied by 100
% m/v =(mass solute)/(volume solution) x 100
Also defined as mass of solute per 100 ml of solution
Usually expressed in g/ml

27. Problems
You dissolve 5.66g KBr in enough H2O to make 27mL of solution. What is the mass/volume percent for the previous solution?
You dissolve 4.44 g NaCl in enough water to make L of solution. What is the mass/volume percent?
You have a 3.98 % m/v solution of NaBr in 350 ml of water. How much NaBr was used to make this solution?

28. Percent by Mass (%m/m): mass of solute in mass of solution multiplied by 100
Also, known as %w/w
Mass % = mass solute/mass solution x 100
Remember: mass solution=mass solute + mass solvent
Also defined as the number of grams of solute per 100g of solution

29. Problems
You make a solution by dissolving 7.55 g NaCl in 52.4g H2O. What is the mass % of solute in this solution?
You make a solution by dissolving 2.45 g KCl in 20.6mL of water. What is the mass % of solute in this solution?
You have a %m/m of 10.0% sucrose. If you used 25.0 g sucrose to make the solution, how much solvent (water) did you use?

30. Percent by volume (% v/v): volume of solute divided by volume of solution multiplied by 100
VP = volume solute/volume solution x 100
Units of volume must be the same for both solute and solvent

31. Problems
You dissolve a 5 cm3 cube of sugar in 20mL of water. What is your volume percent of solute in this solution?
Your bottle of Jack Daniels says that the alcohol content is 14%. What does this mean?

32. More Problems
Your child has an ear infection and is given a suspension of 5.0 % (m/v) amoxicillin. How many grams of the antibiotic is she given in 10mL?
How many milliliters of a 4.0% (m/v) drug are needed if the patient is to receive 0.250g?

33. Dilutions
Dilution: the process by which more solvent is added to a solution in order to lower the concentration
C1V1 = C2V2
C = Concentration
V = Volume

34. Problems
Joan has 50 mL of a M glucose solution. She’d like to dilute this to a M glucose solution. What will her final volume be?
A nurse wants to prepare a 1.0% (m/v) silver nitrate solution from 24 mL or a 3.0% stock solution of silver nitrate. How much water should be added to the 24 mL?
Mary has a 2.5 L bottle of a M NaOH solution. She would like to make 525 mL of a M NaOH solution. How will she do this?

35. Mixtures
Heterogeneous Mixture: a mixture in which the particles of each component remain separate and can be observed as individual substances
See distinct phases
See interface
Solute particle size above 200nm

36. Homogeneous Mixture: a mixture in which the composition is the same throughout
Only one phase present
Cannot see interface
Particle size less than 1nm
Often called “solutions”

37. Colloids
Mixtures with properties intermediate between heterogeneous and homogeneous mixtures
Particles tend to be small enough to pass through filters, but too large to pass through semipermeable membranes (1nm-200nm)
Particles are large enough to scatter light, producing a phenomenon called the Tyndall effect
Examples: Jell-O, Fog, Dust in air, Mayo

38. The Tyndall Effect Named after the Irish scientist John Tyndall
Describes the light scattering effect cause by particles in a colloid
Can see the beam of light
Can see the particles in the colloid
Used to distinguish colloids from other types of mixtures

39. Suspensions Heterogeneous mixtures
Contain particles large enough to be trapped by filters and semipermeable membranes, but small enough to stay suspended for a while before settling out.
Examples: Muddy water, liquid medications, paint
Most things that direct you to shake or stir before using

40. Osmosis
The movement of water, through a semipermeable membrane, from regions of low solute concentration to regions of higher solute concentration
Spontaneous
The membrane must be permeable to the solvent, but not the solute

41. Movement of water to one side of the permeable membrane causes osmotic pressure
Osmotic Pressure is defined as the force per unit area that prevents water from passing through a membrane

42. In living systems, osmotic pressure is called turgor
Pressure of intracellular water and other contents press up against the cell membrane causing the cell to expand
Plant cells are prevented from rupturing by their cell walls
Allows plants to stand upright

43. Hypotonic solution: a situation in which the concentration of solute(s) is higher inside the membrane/cell than in the surrounding solution
Water flows into the cell by osmosis
Causes turgor and/or cell lysis
Hypertonic solution: a situation in which the concentration of solute(s) is lower inside the membrance/cell than in the surrounding solution
Water flows out of the cell by osmosis
Causes cell shrinkage called crenation

44. Isotonic solution: a situation in which the solute concentrations on the inside and outside of a membrane/cell are equal
There in no NET movement of water
Also called “Physiological Solutions”

45. Chapter 8 Review Solutions, solute, and solvent “Like dissolves like”
Solubility
solution types (saturated, super satured, unsaturated)
General Solubility rules for salts
Concentrations- mol/L, m/m%, m/v%, v/v%
Dilutions
Mixture, colloid, suspension
Osmosis

46. Chapter 8 Homework All of it
Read Chapter 9 from textbook, maybe a quiz
Mary has a 2.5 L bottle of a M NaOH solution. She would like to make 525 mL of a M NaOH solution. How will she do this?