Solutions and Acids and Bases

1. Solutions and Acids and Bases

2. Matter http://www.meta-synthesis.com/webbook/31_matter/matter2.jpg

3. Mixtures • Homogeneous mixture: a uniform mixture of only one phase. Example: sugar in water, salt in water. • Heterogeneous mixture: A mixture in which the particles of each component remain separate and can be observed as individual substances.

4. Solutions • Solutions are homogeneous mixtures of substances with at least one solute and one solvent. Eg. Sugar in water. • Liquid and gas state solutions are clear or transparent, and colourless or coloured

5. Solvent and Solute • Solvent – The component of the solution present in greater amount. Solvent dissolves the solute • Solute – The component of the solution present in lesser amount. The solute is dissolved by the solvent.

6. Classifying solutions PG. 192

7. Properties of Aqueous Solution • An aqueous solution has water as the solvent • Symbol is (aq) • Most solutions have water as the solvent therefore most solutions are aqueous. • Solutions can be classified as electrolyte or nonelectrolyte • An aqueous solution can conduct electricity while a nonelectrolyte can not conduct electricity

8. Types of Electrolytes • Salt: Metallic and non-metallic element NaCl and NaHCO3 • Acid: HCl(aq) -> H+(aq) + Cl-(aq) • Base: NaOH(aq) -> Na+(aq) + OH-(aq)

9. Dissociation • Ionic compounds dissolve into their component ions • NaCl(s) -> NaCl(aq) -> Na+(aq) + Cl-(aq) PG 197

10. Dissociation examples • a) Cu2CO3(aq)  ? • b) (NH4)2O (aq) ? • c) BaSO4(aq) ? • d) Ca(HCO3)2(aq) ? • e) H3PO4(aq) ? • f) H2O (aq) ?

11. Dissociation answers • a) Cu2CO3(aq)  2 Cu+(aq) + CO32-(aq) • b) (NH4)2O(aq)  2 NH4+(aq)+ O2-(aq) • c) BaSO4(aq)  Ba2+(aq) + SO42-(aq) • d) Ca(HCO3)2(aq)  Ca2+(aq) + 2HCO3-(aq) • e) H3PO4(aq)  3H+(aq) + PO43-(aq) • f) H2O(aq)  H+(aq) + OH-(aq)

12. Homework • Pg 195 – 1 a,b,e,f • 2 b, d, e

13. Acids and Bases PG 199

14. Energy Changes • Chemical reactions can be exothermic or endothermic. • What type of energy occurs when a substance is dissolved in water? • Energy absorbed when breaking bonds • Energy released when forming new bonds

15. Intermolecular forces • What can you remember from intermolecular forces? • Dipole-dipole • Hydrogen bonding • London foces • How do they effect dissolving? • “Like dissolves like”

16. Substances in Water • Some substances dissolve in water and some substances don’t; limestone vs sodium chloride • Limit to the amount of substance can be added to water? • This is based on the solubility of the substance • Prediction of precipitation reactions using a solubility chart

17. Strong or Weak Acid • Strong acids are almost completely ionized in solution • Very conductive • Weak acids, vary in conductivity

19. Molecular compounds • Use solubility chart for ionic compounds but not an easy fix for molecules • But can predict solubility in water based on IMF (polar liquid with hydrogen bonding) • Nonpolar compounds generally don’t dissvole • Polar compounds are slightly soluble • Polar compounds with hydrogen bonding are very soluble

21. Solution Concentration • Since most solutions are colourless, the amount of substance within the solution is difficult to determine • But can use the amount of the solute and the amount of solvent to find concentration mass/volume Volume/volume mass/mass

22. Parts per Million • This is used for very small quantities • Used when investigating concentration within drinking water

23. Amount Concentration • This is the amount of solute dissolved into one litre of solution • Can write this with [ ] to represent concentration • Eg. [Cl-(aq)] = 0.25 mol/L

24. Summary

25. Calculations • Can use these concentrations to in calculation to determine the amount of a substance within a certain amount of solvent. • Or anything with mass, volume and concentration

26. Concentrations of Ions • Similar to calculations we have done before when looking at the amount of products and reactants is done with concentration • HCl(aq) -> H+(aq) + Cl-(aq) 1 mol1 mol1 mol • Example pg 211

27. Preparation of Solutions • Two methods to prepare solutions • Dilution of a solution • Solid solute dissolved into a solution • Juice from powder Pg 215

28. Standard solutions by Dilution • Making fruit juice from concentrate • Start with a stock solution and dilute to the desired concentration • To calculate a new concentration, the amount of substance is the same (mass or number of moles) As the volume increases the concentration decreases Example pg 217

29. Uses in everyday life • Needed for drugs or cough syrup • Fruit juices • Laundry detergent

30. Solubility • Solutions are the best way to deal with various chemical reactions • Gases and solids are harder to control • Three points to make solutions useful: • Handle the chemicals • Complete reactions • Controlled reactions

31. Solubility of solids • When solids are added to a solution there is only a certain amount that will dissolved • Once no more substance will dissolved have a saturated solution • Has the units % W/V or mol/L similar to concentration • Temperature can change that maximum level • Remember the solute is dissolving into the solvent not reacting with the solvent

32. Solubility in Water • Solids: increase solubility when the temperature is increased • Gases: decrease in solubility when the T increases, also increase solubility at increased P • Liquids: polar liquids have increased solubility with increase T; nonpolar liquids form layers with water (immiscible) and are insoluble; some polar molecules dissolve completely, miscible

33. Homework • Pg 219: #4, 5, 6, 8

34. Solubility table