Understanding Water and Solutions: Key Concepts from Chapter 11
This chapter explores the unique properties of water, emphasizing its polarity and molecular structure. Water’s behavior as a solvent is critical, distinguishing between solutes and solvents in solutions. Students will learn about the characteristics of electrolytes and nonelectrolytes, and the differences between acids and bases, including their effects on pH and conductivity. Visual aids such as diagrams and graphs illustrate these concepts. This homework assignment encourages applying theoretical knowledge to practical examples from everyday substances.
Understanding Water and Solutions: Key Concepts from Chapter 11
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Presentation Transcript
Water and Solutions Chapter 11
Homework for Chap 11 Read p 275 – 280; 284 - 290 Applying the Concepts # 1 – 3; 9 - 24
Fig. 11.2 (A) The water molecule is polar (It has a dipole.) H2O Fig. 11.2 (B) Attractions between water molecules
Ice is less dense than water Fig. 11.3 The hexagonal structure of ice Water is a Unique Substance:
Maximum Density 4 °C Fig. 11.4 The density of water just above its freezing point Density of Water
Solution Solvent Solute Solution - a homogenous mixture of 2 or more substances Solute - the substance(s) present in the smaller amount(s) Solvent - the substance present in the larger amount Soft drink (l) H2O Sugar, CO2 Air (g) N2 O2, Ar, CH4 Pb Sn Soft Solder (s)
nonelectrolyte strong electrolyte Electrolyte - a substance that, when dissolved in water, forms a solution that can conduct electricity. Nonelectrolyte - a substance that, when dissolved, forms a solution that does not conduct electricity.
Fig. 11.11 The reaction of water and hydrogen chloride Hydronium ion
acid + base salt + water HCl (aq) + NaOH (aq) NaCl (aq) + H2O Acids, Bases, and Salts
Acids • Have a sour taste. e.g., Vinegar, lemons, limes, sour milk • Cause litmus to change from blue to red. 3. Acids neutralize bases. 4. Acid solutions conduct electricity. Fig 11.14 (A)
Bases 1. Have a bitter taste. e.g., caffeine, walnuts, soap 2. Cause litmus to change from red to blue. 3. Feel slippery. Many soaps contain bases. 4. Bases neutralize acids. 5. Basic solutions conduct electricity. Fig 11.14 (B)
How do we express the concentration of an acid or a base? pH scale – based on concentration of the hydronium ion (H3O+) acidic neutral basic 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Based on powers of 10: e.g., a soln with pH = 3 is 10 times more acidic than a solution with pH = 4
