Solution Chemistry & Properties of Water

1. Solution Chemistry & Properties of Water

2. Mixtures Review • Homogeneous • Solutions • Heterogeneous • Suspension - is a fluid containing solid particles that are sufficiently large enough to settle. • Colloid - is a substance microscopically dispersed evenly throughout another substance. • Emulsion - is a mixture of two or more immiscible (unblendable) liquids.

3. Characteristics of solutions • Solution – homogeneous mixture a) parts of a solution i) solute – substance being dissolved ii) solvent – substance doing dissolving both can be either solid, liquid, or gas

4. Solubility • Soluble – substance can dissolve in a solvent ex: salt in water • Insoluble – substance cannot dissolve in a solvent ex: sand in water

5. Solvation In Aqueous Solutions • Solvation – process of surrounding solute particles with solvent particles Why are some substances soluble in a solvent and some others are not? must be compatibility between solute and solvent

6. “like dissolves like” • Defn – rule used to determine if substance will dissolve in another - based on attractive forces between solute and solvent

7. “like dissolves like” • polar solvents – dissolve polar molecular compounds and ionic compounds ex: salt and water, alcohol and vinegar • nonpolar solvents – dissolve nonpolar compounds only ex: oil and gasoline

8. Factors Affecting Rate of Solvation • How can you dissolve something faster??? • increase temp of solvent this accelerates particles creating more particle collisions

9. Factors Affecting Rate of Solvation • agitate the solution more particle collisions between solute and solvent • Increase surface area of solute breaking into smaller pieces allows more solute to be in contact w/ solvent

10. Solubility • Defn – max amt of solute that can dissolve in a solvent at a specific temp how much solute can be put into solvent?

11. Unsaturated Solution • Defn – less than max amt of solute dissolved if I put sugar into water and all sugar is dissolved, solution is unsaturated

12. Saturated Solution • Defn – contains max amt of solute dissolved if I put sugar into water and not dissolves (you can see the sugar), the solution is saturated

13. Supersaturated Solution • Defn – contains more solute than saturated solution at the same conditions a saturated solution made at high temp cools slowly. Slow cooling allows excess solute to remain dissolved in solution at lower temperature very unstable

14. UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form Sum up Solubility concentration

15. Saturated-Line represents max amount solute that will dissolve at a given temperature Solubility Curve Supersaturated (above line) Solubility (g solute/ 100 g H2O) Unsaturated (below line) Temperature

17. How does temp affect solubility? • The higher the temp, higher the solubility (for most cases)

18. Solution Concentration • Concentration – how much solute dissolved in amount of solvent what is difference between concentrated and diluted?

19. Concentrated vs. Dilute

20. Concentration • 3 different units of concentration a) percent by mass b) molarity (M) c) molality (m)

21. Colligative Properties of Solutions • Solutes affect the physical properties of their solvents • Colligative properties (defn) – properties that depend only on the number of solute particles present, not their identity • Ex: boiling point, freezing point

22. Electrolytes • Defn – substances that break up (ionize) in water to produce ions; can conduct electricity - consist of acids, bases, ionic compounds Ex: NaCl  Na1+ + Cl1- H2SO4  2 H+ + SO42-

23. Nonelectrolytes • Defn – do not break up (ionize) in water, they stay the same; doesn’t conduct electricity - usually molecular/covalent compounds Ex: sugar C6H12O6 C6H12O6 ethanol C2H5OH  C2H5OH

24. Acids & Bases

25. Electrolytes Electrolytes Sour Taste Bitter taste Turn Litmus Red Turn Litmus Blue React with Metals to Slippery feel Form Hydrogen gas Ex. Ammonia, Ex. Vinegar, milk, soda lye, antacids, Apples, citrus fruits baking soda Properties ACIDS BASES ChemASAP

26. Strength of Acids & Bases Strong Acid/Base 100% ionized in water, comes apart completely in water Strong electrolyte, conducts electricity Strong Acids: HCl, HNO3, H2SO4 Strong Bases: NaOH, KOH

27. Strength of Acids & Bases • Weak Acid/Base • Does not ionize completely, does not come apart completely in water • Weak electrolyte, does not conduct electricity well. • Weak Acids: HF, CH3COOH • Weak Base: NH3

28. Neutralization Reactions Strong acid + Strong base  Salt + Water Ex. HCl(aq) + NaOH(aq) NaCl(aq)+ H2O

29. pH Acids & Bases

30. The pH Scale The pH scale indicates the hydronium ion concentration, [H3O+] In other words how many H3O+ ions are in a solution. If there are a lot we assume it is an acid, if there are very few it is a base.

31. The pH Scale 14 0 7 INCREASING BASICITY INCREASING ACIDITY NEUTRAL

32. The pH Scale pH of Common Substances

33. Acid/Base Indicators • An acid-base indicator is a weak acid or a weak base. • An Indicator changes color over a range of hydrogen ion concentrations. This range is expressed as a pH range. • Some common indicators are: litmus paper, cabbage juice, phenolphthalein bromthymol blue etc.

34. Acid/Base Indicators -Litmus Paper • Litmus paper is paper that has been treated with a specific indicator • Litmus paper turns red in acidic conditions (pH < 7) • Litmus paper turns blue under alkaline conditions (pH > 7).

35. Properties of Water

36. Water is polar because oxygen is a “bully” and does not share the electrons. Oxygen is negative with more electrons and Hydrogen is positive with less electrons. Water is Polar

37. Cohesion is the attraction of the same type of molecules to each other. Water molecules stick together and “hold hands” with hydrogen bonds Cohesion

38. Water is polar and can dissolve both salts, sugars, and other molecules. Water is the Universal Solvent

39. Adhesion is the attraction of molecules between two different substances. Example: The attraction of water molecules to a glass. Adhesion

40. Adhesion causes the water molecules to stick to the sides of the graduated cylinder creating a meniscus. Adhesion causes water to rise in a straw. Adhesion

41. Property of water – a water molecule can split to form ions and make acids and bases. Acid: pH 0-6.9 H+ ions Base: pH 7.1-14 OH- ions Water: Acids and Bases