UNIT 10: SOLUTIONS TEST on 5/1/14

1. UNIT 10: SOLUTIONSTEST on 5/1/14

2. Notes #1: Unique Role of Water • Importance of Water to Life • Living cells are 70% - 95%water. • The surface of the earthis approximately 70.9%water. • Water is the only substance on earth that naturally occurs in all three states– solid, liquid, and gas. • Life is dependent upon water and its unique properties.

3. Notes #1: Unique Role of Water • Importance of Water to Life • Most of the reactions that take place in living organisms involve water, such as photosynthesis and cellular respiration. • Background: What is water? • Water is a puresubstance, a compound, of hydrogen and oxygen chemically bonded to form a single substance. • Electrolysisbreaks down water into hydrogen and oxygen.

4. Solutions Video • http://www.youtube.com/watch?v=3G472AA3SEs

5. Polar or Nonpolar? • It boils down to symmetry. If the molecule looks like a copy of itself from top to bottom and left to right, then it’s going to be nonpolar. H H vs.

6. NOTES #2: Solutions • What is a solution? A homogeneous mixture of two or more substances • Solute? Substance dissolved in a solution • Solvent? The dissolving agent of a solution • In the example pictured, identify the solute, solvent, and solution.

7. Solubility • Definition: Maximum amount solute that can be dissolved in a given amount of solvent at a specific temperature and pressure. • Remember, Like Dissolves Like! • Nerdy Riddle of the Day: Why do white bears dissolve in water? Because they’re polar!

8. Solubility • Soluble – Substances able to be dissolved • Insoluble – Substances unable to be dissolved Types of Solutions • Aqueous Solutions: Homogeneous mixtures in which water is the solvent

9. Aqueous Solutions • Liquids can dissolve in other liquids to form solutions. Such liquids are defined as miscible. • Example: alcohol and water • If two liquids do not dissolve in one another, but rather separateupon standing, those liquids are defined as immiscible. • Example: oil and water, or water and the “lava” in a lava lamp

10. Types of Solutions • Electrolytes – Compounds that conduct electricity. All ioniccompounds form electrolytes when dissolved in water. • Nonelectrolytes – Do not conduct an electric currentin aqueous solution or in moltenform. Many molecular compounds are nonelectrolytes • Alloys – Solids that dissolve in other solids • Examples: brass, steel, etc

11. Video Clip:Ionic vs. Covalent Solutions • Click each compound to view: Salt (ionic compound) - NaCl Sugar (covalent compound) - C12H22O11

12. Solutions vs. Things That Just Look Like Them… Something to think about… • Is milk a solution? What about muddy water, dust particles floating or suspended in the air, or just the different gases – N2 , O2 , CO2 , H2O(g), Ar, etc. – that make up the pure, unpolluted air we breathe? • We’ll come back to this later!

13. What makes a solution…a solution? • Solutions are always transparent, meaning that light passes through with no scattering from tiny solute particles – a solution may have a "color" but it will still be transparent. • The solute component of a solution can be atoms, ions, or molecules, and will measure between 0.1 to 2nm in diameter. • Solutions are homogeneousand don’t settle out • Solutions cannot be filtered, but can be separated using the process of distillation.

14. Back to Basics: Mixtures • Homogeneous Mixture: Mixture that has the same uniform appearance and composition throughout. May exist as gas, liquid or solid, depending on state of solvent. • Heterogeneous Mixture: Mixture that is not uniform in composition

15. The 3 special types of heterogeneous mixtures that look like solutions… • Suspensions: Heterogeneous mixtures with particles that have diameters greater than 1000 nm. The particles of a suspension will separate upon standing. • Colloids: Heterogeneous mixture containing particles that are intermediatein size between those found in suspensions and true solutions that remain evenly distributedwithout settling out due to Brownian Motion.

16. The 3 special types of heterogeneous mixtures that look like solutions… • Emulsions: Heterogeneous, colloidal dispersions of liquid particles in a liquid medium. • An Emulsion is a colloid- Shaving cream

17. Difference between a solution, suspension, colloid, and emulsion: • Suspensions will eventually separate; whereas colloids and solutions will not. • Colloids can be distinguished from solutions using the Tyndall effect. • A beam of light passing through a true solution, such as pure unpolluted air/water, is not visible. Light passing through a colloidal dispersion, such as smoky or foggy air, will be reflected by the larger particlesand the light beam will be visible.

18. Solutions vs. Things That Just Look Like Them… • Is milk a solution? • What about muddy water? • Dust particles floating or suspended in the air? • The different gases that make up the pure, unpolluted air we breathe?

19. Snow Globe Lab

20. DAY 2 Solvation

21. To Dissolve or Not to Dissolve • Solvation, also called dissolution, is the process of attraction of molecules of a solvent with molecules or ions of a solute. • Forces between solute-solute molecules and solvent-solvent molecules must be broken before new solute-solvent attractive forces can form.

22. To Dissolve or Not to Dissolve • Dissolution will occur if the solute-solvent forces of attraction are strongerthan the attractive forces keeping the solute together and those forces keeping the solvent together. • Dissolving will not occur if particles of a solute are more attracted to other solute particlesthan to the solvent. Same is true for solvent particles. • Generally, if all three of the intermolecular forces of attraction are roughly equal, the substanceswill be soluble in each other.

23. Factors Affecting Rate of Dissolution • Agitation or Stirring: • Increases rate of dissolution, meaning the solute dissolves faster. • Particle size: • Smaller particle size increasessurfaces area and dissolves faster.

24. Factors Affecting Rate of Dissolution • Temperature: • Heating increasescollisions between particles causing solute to dissolve faster. • Pressure(gases only): • Increasing pressure increasescollisions of gases, meaning that a gaseoussolutewill dissolve faster.

25. Concentration • This is one of the important properties of a solution. Concentration is a measure of solute dissolved in the solvent of a solution. • Concentrated – Solution containing a large amount of solutedissolved in solvent • Dilute – Solution containing a little amount of solutedissolved in solvent.

26. Concentration Example • Example: Vinegaris a dilute acetic acid solution • Vinegaris used in cooking or combined with oil in vinaigrette salad dressings. • Concentrated acetic acid will kill you if ingested. • The only difference between such solutions is the concentrationof the solute.

27. Solubility Curves: Graphs that show the maximum amount of solute dissolved in 100g. Solvent at a specific temperature DAY 4: 3/17/14 NOTES #5: Solubility Curves Booklet Page 18 Homework Page 19

28. Solubility Curves • Solubility: The amount of solute that dissolves per unit of solvent at a specific temperature and pressure to produce a saturated solution. Concentration of Solutions: Saturated, Unsaturated, or Supersaturated? • Saturated: A solution containing the maximum amount of solute per given amount of solvent at a constant temperature and pressure.

29. Solubility Curves • Unsaturated: A solution that contains less solute than a saturated solution at a given temperature and pressure. • Supersaturated: A solution that contains more solute than it can theoretically hold at a given temperature.

30. Color code your graph exactly as shown to the left AND make a key: You need yellow, brown, orange, red, black, green, dark blue, purple, and light blue

31. KNO3 How many grams of KNO3 can be dissolved in 100g of H2O at 50°C? If 70g of KNO3 is dissolved in 100g of water at 50°C, is the solution unsaturated, saturated, or supersaturated? Let’s look at saturated, unsaturated, and supersaturated on a solubility curve! Take a look at KNO3? What portions of the graph represent an unsaturated solution Of KNO3? Which portion of the graph represent a supersaturated solution of KNO3?

32. KNO3 If 105g of KNO3 is dissolved in 100g of water at 50°C, is the solution unsaturated, saturated, or supersaturated?

33. Indicate whether the following are saturated, unsaturated, or supersaturated solutions: 30g of NaCl in 100g of H2O at 80°C. 120g of KNO3 in 100g of H2O at 60°C. 92 g of NaNO3 in 100g of H2O at 10°C.