1. Chapter 23
SOLUTIONS

2. What is a solution?
Solution—a mixture that has the same composition, color, density, and even taste throughout
Ex: hummingbird food-has both sugar and red dye in the solution
Solute—the substance being dissolved in a solution
Solvent—the substance doing the dissolving in the solution

3. More on solutions
Solutions can be composed of any combination of solids, liquids and gases
Ex: air is a solution of 78% nitrogen, 20% oxygen and small amts of other gases such as argon, carbon dioxide and hydrogen
Alloys-solid solutions
They are made by melting the metal solute and solvent together

4. Dissolving Dissolving solids in liquids
Ex: hummingbird food, fruit drinks/sports drinks
How do solids dissolve in water?
Water molecules are constantly moving
Water molecules are also polar, and solute molecules are polar as well
Ex: pg. 709/Figure 3

5. How it Happens
Water molecules cluster around solute molecules w/negative ends attracted to positive ends of the solute
Water molecules pull the solute molecules into solution
Water molecules and the solute molecules mix evenly, forming a solution

6. Dissolving Liquids and Gases
When a gas dissolves in a liquid, particles of liquids and gases move much more freely than do particles of solids
When gases dissolve in gases or when liquids dissolve in liquids, this movement spreads solutes evenly throughout the solvent

7. Dissolving Solids in Solids
In order to mix to solids, ,
Ex: two solid metals are first melted and then mixed together.
In this liquid state, the metal atoms can spread out evenly and will remain mixed when cooled

8. Rate of Dissolving
Stirring-a solutionspeeds up dissolving because it brings more fresh solvent into contact w/more solute
Grinding lg. crystals (solids) into smaller ones speeds of dissolving also
Temperature—increasing temperature of the solvent always speeds up the dissolving rate
Ex: hot chocolate

9. Gases in Solution
When you shake an opened bottle of soda, it bubbles up and may squirt out
Shaking or pouring a solution of a gas in a liquid causes gas to come out of solution
If you want to dissolve more gas in a liquid, you can increase the pressure of that gas over the liquid
Ex: soft drinks (carbon dioxide pressure)

10. Temperature
Another way to increase the amount of gas that dissolves in a liquid is to cool the liquid
Ex: even more carbon dioxide will bubble out of a soft drink as it gets warmer

11. Section 2—Dissolving w/out Water
**Water can’t dissolve some solutes because of its polarity
**However, non-polar materials have no separated positive and negative areas.
**Non-polar materials do not attract polar materials, which means they do not attract water
SO:**Non-polar materials DO NOT dissolve in water

12. Non-polar Solutes
Ex: vinegar and oil salad dressing has two layers—bottom layer is vinegar, and top layer is salad oil
Equal distribution of electrons means the molecules of oil have no separate positive and negative areas, so they will not mix with water.

13. Versatile Alcohol
Some substances form solutions w/polar and non-polar solutes
They have molecules with both polar and non-polar ends
The polar end dissolves polar substances, and vice versa.
Ex: ethanol dissolves iodine and water

14. Useful Non-Polar Solvents
Mineral Oil—used as a solvent to remove candle wax from glass, or metal or bubble gum from some surfaces
Oil-based paints have materials dissolved in oils, so a non-polar solvent must be used to thin or remove them
Dry cleaners use non-polar solvents when removing oily stains

15. Toxicity
Although non-polar solvents have many uses, they have some drawbacks, too.____
1. Many are flammable
2. Some are toxic (skin/inhalation, etc)
You must always be careful when handling these materials, and use a well ventilated area

16. How Soap Works
The oils on human skin and hair keep them from drying out, but the oils can also attract and hold dirt
Oily dirt is a nonpolar mixture, so e must wash with soap to get rid of dirt
SOAP-has both non-polar and polar properties
Soap is used to remove dirt from skin, hair, or fabric by attaching oily dirt to the hydrocarbon end and water to the ionic end

17. Polarity and Vitamins
Having the right kinds and amounts of vitamins is important for your health
B vitamins and vitamin C are polar compounds=they dissolve in water (water soluble)
You must replace these vitamins by eating enough of the foods that contain them or by taking vitamin supplements

18. Fat-Soluble Vitamins
Some vitamins such as vitamin A are non-polar and can dissolve in fat
They do not wash away with water and are not easily eliminated by the body
They can accumulate in tissues, which can become toxic
Other ex: Vitamins D, E and K

19. Section 3—Solubility
Solubility-the max amt. of a solute that can be dissolved in a given amt. of solvent at a given temp.
The amount of a substance that can dissolve in a solvent depends on the nature of these substances
Explanation of how to determine solubility-pg. 718

20. Concentration Ex: You add 1 tsp. of lemon juice to a glass of water
Your friend adds 4 tsps. Of lemon juice to another glass the same size
You could say your friend’s lemonade is concentrated, and your glass is dilute because your friend’s drink now has more lemon flavor than yours

21. More on Concentration/Dilution
A concentrated solution is one in which a large amount of solute is dissolved in the solvent
A dilute solution is one that has a small amount of solute in the solvent
To measure concentration precisely it is sometimes given as a percent
(% fruit juice, etc.)

22. Types of Solutions
Saturated solution-a solution that contains all the solute it can hold at a given temperature.
(if heated, however, it could hold more)
SO: as the temp of a liquid solvent increases, the amt of solid solute it can dissolve also increases

23. Types of Solutions
Unsaturated solution—a solution that can dissolve more solute at a given temperature
Each time a saturated solution is heated to a higher temp, it becomes unsaturated

24. Types of Solutions
Supersaturated Solution-a solution that contains more solute than a saturated one at the same temperature
Ex: if a seed crystal of sodium acetate is dropped into the supersaturated solution, excess sodium acetate crystallizes out

25. Solution Energy
Some portable heat packs use crystallization from supersaturated solutions to produce heat
After crystallization, the heat pack can be reused by heating it to again dissolve all the solute.

26. Section 4-Particles in Solution
Ions-the charged particles in the fluids that are in and around all the cells in your body
Electrolytes—the compounds that produce solutions of ions that conduct electricity in water
there are both strong (soldium chloride) and weak electroylytes (acetic acid)
Nonelectrolytes—substances that form no ions in water and cannot conduct electricity
Ex: ethyl alcohol and sucrose

27. How Ionic Solutions Form
To form ions, the molecules must be broken apart in such a way that the atoms take on a charge
Ionization—the process of forming ions so that molecules are broken apart and atoms take on a charge
Dissociation—the process in which an ionic solid, such as sodium chloride, separates into its positive and negative ions
Ex: pg. 724

28. Effects of Solute Particles
All solute particles-polar and nonpolar, electrolyte and nonelectrolyte, affect the physical properties of the solvent, such as its freezing point and its boiling point
Ex: adding antifreeze to water in a car radiator lowers the freezing point of the radiator fluid
(sugar and salt would do the same thing)

29. The effect that a solute has on the freezing pt or boiling pt of a solvent depends on the number of solute particles in solution, NOT on the chemical nature of the particles
(it’s not a chemical reaction)

30. Lowering Freezing Point
Adding antifreeze to a solvent lowers the freezing point of the solvent
How much the freezing point goes down depends upon how many solute particles you add.

31. Raising Boiling Point
Antifreeze also raises the boiling point of the water
The amount the boiling point is raised depends upon the number solute molecules present
Solute particles interfere w/evaporation of solvent particles

32. More on Raising the Boiling Point
More energy is needed for the solvent particles to escape from the liquid surface, so the boiling point of the solution will be higher than the boiling point of solvent alone

33. Car Radiators
When a car radiator contains water only, no antifreeze, the following occurs:
Some of the molecules on the surface will vaporize and the number of molecules that do vaporize depends upon the temp of the solvent
When the solvent heats up, the molecules move faster, and particles vaporize
Finally when pressure of water vapor equals atmospheric pressure, water BOILS