1. Chapter 8 : SOLUTIONS Section 1 – Solutions and Other Mixtures
Section 2 – How Substances Dissolve
Section 3 – Solubility and Concentration

2. 1 - Solutions and Other Mixtures
Key Questions
What is a heterogeneous mixture?
What is a homogeneous mixture?
State Standards
CLE : Evaluate pure substances and mixtures

3. Heterogeneous Mixtures
Does not appear uniform ( microscope needed )
Does not have a fixed composition
Amounts of each component vary in distinct samples
Another example – Granite
Mixture of minerals
Different types of Granite
Internet Break??

4. Oil and Water Do oil and water mix? Maybe but will separate quickly
Depends on type of oil
Immiscible or Miscible?
Oil and Water are IMMISCIBLE
Alcohol and Water are MISCIBLE

5. Suspensions Orange Juice – another heterogeneous mixture
Suspensions have large particles that settle out
Particles may also be filtered out

6. Colloids
Colloids are suspensions with particles too small to settle out – they remain suspended always
Can scatter light
Tyndall Effect
FOG!!

7. Common Colloids FOG!!!! Emulsions: Colloids made of liquids
that do not normally mix
Mayo ( oil droplets in vinegar )
Milk/Cream ( oil droplets in water )
Lotions, creams, many cosmetics

8. Homogeneous Mixtures Appear uniform even when using a microscope
May look like pure substance but they are not
They are Solutions – components are uniformly spread throughout each other
Solute – substance being dissolved
Solvent – substance dissolving the solute

9. Homogeneous Mixtures Example – SALTWATER
Water is SOLVENT / Salt is SOLUTE

10. Solutions Miscible liquids mix
form solutions
Solids not always involved
Water is not always involved ( can mix alcohols ) in liquid solutions
Other states of matter can form solutions
Solids can dissolve in other solids
Metal ALLOYS ( Brass is Zn and Cu )
Tooth Fillings ( used to be Ag/Hg but now are plastics )

11. How is Crude Oil turned into Gasoline?

12. 1 - Solutions and Other Mixtures
Key Questions
What is a heterogeneous mixture?
What is a homogeneous mixture?
State Standards
CLE : Evaluate pure substances and mixtures

13. 2 - How Substances Dissolve
Key Questions
Why is water called the universal solvent?
Why do substances dissolve?
State Standards
CLE.3202.TE.3 : Explain the relationship between the properties of a material and the use of the material in the application of a technology
CLE : Distinguish between common ionic and covalent compounds

14. Water : A Common Solvent
Water is called the universal solvent because many substances can dissolve in water
Water can dissolve ionic compounds
A polar molecule has partially charged + and – areas ( water is polar )
Charge is not evenly distributed in polar molecules

15. Dissolving – Depends of Forces
Polar water molecules pull ionic crystals apart
Na+, Cl- attracted more to water “poles” than each other
Dissolving depends on forces between particles
Goto go.hrw.com and enter keyword “HK8SOLF2”

16. Like dissolves Like This is a rule in chemistry!!
Water dissolves many molecular compounds
Recall that O in water pulls electrons away from H
This forms a Hydrogen Bond (pull H2O close together)
Water dissolves compounds with hydrogen bonds
Examples are alcohols, sugar, vitamin C

17. Like dissolves Like
Nonpolar compounds ( liquids ) dissolve other nonpolar compounds
Nonpolars do not have their +/- charges separated
Why oils do not dissolve in water
But one oil WILL dissolve another oil

18. The Dissolving Process
Kinetic Theory (molecules are always moving)
Dissolving occurs because:
Energy transferred from solvent to solute (collisions upon addition of solute)
Attractive forces between solute and solvent

19. The Dissolving Process
Solutes with larger surface area dissolve faster
What is surface area of a sphere ?
( 4πr2 )
Small particles of salt will dissolve faster than a large chunk of salt

20. The Dissolving Process
Stirring or shaking helps dissolve solids faster
Hot solvents dissolve solids faster than cold ones
Solutes affect the physical properties of a solution
Boiling & Melting temperature ( salted roads!! )

21. 2 - How Substances Dissolve
Key Questions
Why is water called the universal solvent?
Why do substances dissolve?

22. 3 – Solubility and Concentration
Key Questions
What is solubility?
What happens when you add more solute to a saturated solution?
How do you describe how much of a solute is in a solution?
State Standards
CLE.3202.Inq.3 : Use appropriate tools and technology to collect precise and accurate data
CLE.3202.Inq.6 : Communicate and defend scientific findings ( LAB!! )

23. Solubility in Water
The solubility of a substance is the maximum mass of a solute that can dissolve in 100 g of solvent at a certain temperature and standard atmospheric pressure
Different solutes have different solubilities
Examples at 20 oC:
Salt ( NaCl ) has solubility of 35.9 g / 100 g H2O
Sodium Iodide ( NaI ) – 178 g / 100 g H2O
Iron(II) Sulfide ( FeS ) – g / 100 g H2O

24. Concentration
Concentration is the quantity of solute that is dissolved in a given volume of solution
Concentrated solution has a lot of solute
Dilute solution has small amount of solute
Qualitative terms – would like to know a value
Salt ( NaCl ) max solubility of 35.9 g / 100 g H2O
This gives a concentration of g/mL at 20 oC

25. Concentration Salt ( NaCl ) max solubility of 35.9 g / 100 g H2O
This gives a concentration of g/mL at 20 oC
Molarity is a common way to express this
Salt max solubility above becomes ~ 6.15 mol/L
𝒎𝒐𝒍𝒂𝒓𝒊𝒕𝒚= 𝒎𝒐𝒍𝒆𝒔 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒆 𝒍𝒊𝒕𝒆𝒓𝒔 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏 = 𝒎𝒐𝒍 𝑳 or M

26. Saturated Solutions
In saturated solutions, dissolved solute is in equilibrium with undissolved solute
So, more solute added just settles to bottom
Unsaturated solutions can become saturated by adding enough solute

27. Temperature and Pressure
Heating a saturated solution can dissolve more solute ( can also increase maximum solubility )
Why solubility values given at 20 oC
Temperature and pressure affect gas solubility
Pressure inside sealed coke is higher then an open one

28. 3 – Solubility and Concentration
Key Questions
What is solubility?
What happens when you add more solute to a saturated solution?
How do you describe how much of a solute is in a solution?

29. Gas Solubility Lab