1. Aqueous Solutions Section 17.3

2. After reading Section 17.3, you should know: • The meaning of “likes dissolve likes” and how to determine which compounds will dissolve into each other • The difference between strong, weak and non-electrolytes • The difference between hygroscopic and deliquescent substances

3. Solvent vs Solute • Aqueous Solutions – water samples containing dissolved substances • Solvent – the substance doing the dissolving • Solute – the substance being dissolved • Example of an aqueous solution = salt water • Solvent = water • Solute = salt

4. Review: Ionic and Covalent • Ionic comounds = metal + nonmetal • Held together by ionic charges • Polar Covalent molecules = 2 or more nonmetals • Have a slight charge due to electronegativity differences • Nonpolar Covalent molecules = 2 or more nonmetals • Do not have a charge because the shape of the molecule cancels the electronegativity differences out

5. “Likes Dissolve Likes” • Ionic compounds and polar compounds will dissolve in other ionic and polar compounds • Ionic compounds have a full charge and polar compounds have a slight charge, so the charges are attracted to each other. • Nonpolar compounds will only dissolve in other nonpolar compounds

6. Salt will dissolve in water • Salt is ionic, water is polar • Oil and water do not mix • Oil is nonpolar and water is polar

7. Solutions • Solutions are homogenous mixtures • Solvation – the process that occurs when a solute dissolves • Example: salt dissolving in water • Salt is an ionic compound, water is a polar molecule • Animation of salt water and the interactions between the molecules

8. Electrolytes and Nonelectrolytes • Electrolytes – compounds that conduct an electric current in aqueous solution or the molten state • All ionic compounds are electrolytes • Nonelectrolytes - compounds that do not conduct an electric current in aqueous solution or the molten state

9. Strong electrolyte – when a substance is dissolved and almost all of the solute molecules separate into ions • Weak electrolytes – when a substance is dissolved and only a fraction of the dissolved solute separate into ions • Table 17.3 on page 485

10. Water of Hydration • Water of hydration is the water contained in a crystal • Hydrate – a compound containing water • Example: copper (II) sulfate pentahydrate • CuSO4*5H2O • Table 17.4 on page 486

11. Effloresce – process that occurs when a hydrate has a vapor pressure higher than that of water vapor in the air • Hygroscopic – substances that remove water from the air • Have low vapor pressure • Used as desiccants or drying agents

12. Deliquescent – compounds that remove a sufficient water from the air to dissolve completely and form solutions • When a substance has a lower vapor pressure that that of the water in the air • Example: solid NaOH pellets – react with moisture from the air and will “melt” over time

13. After reading Section 17.3, you should know: • The meaning of “likes dissolve likes” and how to determine which compounds will dissolve into each other • The difference between strong, weak and non-electrolytes • The difference between hygroscopic and deliquescent substances