1. Solutions & Solubility SCH3U Chapter 6

2. Chemistry Literature Connection “Water does not resist. Water flows. When you plunge your hand into it, all you feel is a caress. Water is not a solid wall, it will not stop you. But water always goes where it wants to go, and nothing in the end can stand against it. Water is patient. Dripping water wears away a stone. Remember that, my child. Remember you are half water. If you can't go through an obstacle, go around it. Water does.” ― Margaret Atwood, The Penelopiad

3. Remember: Periodic Trends - Electronegativity Electronegativity = a number that describes the ability of an atom to attract electrons More electronegative = stronger pull on electrons being shared Less electronegative = weaker pull on electrons being shared

4. Trend: Electronegativity Increasing

5. Difference in Electronegativity If the electronegativity difference is: less than 0.2 = bond is non-polar covalent is between 0.2 and 1.6 = bond is polar covalent is greater than 1.7 = bond is ionic

6. Types of Bonds Non-Polar Covalent = the attractive forces between two atoms that results when electrons are equally shared by the atoms with similar electronegativities Polar Covalent = a covalent bond formed between atoms with significantly different electronegativities resulting in unequal sharing of electrons Ionic = a bond formed due a large difference in electronegativity between atoms resulting in a complete transfer of electrons

7. Comparison…

8. Non-Polar versus Polar Covalent

10. Structure & Shape of Water Lone Pair

11. Structure & Shape of Water

12. Polarity of Water Molecules Electronegativity difference O = 3.5 H = 2.1 3.5 – 2.1 = 1.4 Recall: between 0.2 and 1.6 = bond is polar covalent

13. Polarity of Water Molecules Dipole moment =measure the polarity of a chemical bond, occurs whenever there is a separation of positive and negative charges

14. Hydrogen Bonding

15. Ionic Compounds in Water

17. Polar Molecules in Water Hydrogen Bonding

18. Polar Molecules (Sugar) in Water

20. Non-Polar Molecules in Water

21. “like dissolves like” Polar substances dissolve in polar solutions Non-polar substances dissolve in non-polar solutions In other words: like-polarity substances dissolve in each other

22. Concentration = Solution Concentration

23. Percentage Concentration

24. Very Low Concentrations Parts per million (ppm) = units used for very low concentrations Used for very dilute solutions Example: Toxic substances found in the environment Chlorine in a swimming pool Metals in drinking water

25. Molar Concentrations Molar Concentrations (C)= the amount of solute, in moles, dissolved in one liter of solution C = n/v Units = mol/L Molarity of a solution

26. Solution Preparation Standard Solution = a solution for which the precise concentration is known Used in research laboratories and industrial processes Used in chemical analysis and precise control of chemical reactions

27. Equipment needed to prepare a standard solution: Electronic balance Volumetric flask Solution Preparation

28. Accurate Reading of a Volumetric Flask

29. Volumetric Graduated & Pipets and Bulb to transfer small quantities of liquid

30. Preparing a Solution by Dilution Dilution = the process of decreasing the concentration of a solution, usually by adding more solvent Stock Solution = a solution that is in stock or on the shelf (i.e., available); usually a concentrated solution

31. Preparation of a Solution of Known Concentration by Diluting a Stock Solution

32. Preparation of a Solution of Known Concentration Using a Solid Solute

33. Calculating the New Concentration of the Diluted Solution C 1 x V 1 = C 2 x V 2 C 1 = initial concentration V 1 = initial volume C 2 = final concentration V 2 = final volume