Dissolving and Solubility Chapter 6 Section 2 notes Dissolving and Solubility
Dissolving and Solubility The dissolving Process: 3 factors that affect solubility Solutes with larger surface area dissolve faster. Why When solids are whole, the particles are buried. But, when the substance is broken up, there is a larger surface area, and more collisions occur between the solute & solvent Example: loose sugar dissolves faster than a sugar cube
Stirring helps a solute to dissolve faster. Why? Stirring moves the dissolved solute away so that new solute can interact with the solvent. Solutes dissolve faster when the solvent is hot. Why? As a substance is heated, the particles collide more often and the solute dissolves faster.
Not every substance dissolves: If a substance dissolves in water, it is soluble If a substance doesn’t dissolve, it is insoluble If a substance partially dissolves in water, it is partly soluble Because water can dissolve many substances, it is said to be the universal solvent
The structure of a water molecule: There is 1 oxygen atom and 2 hydrogen atoms. Oxygen has a partial negative charge because oxygen attracts the electrons from hydrogen. Hydrogen has a partial positive charge. Therefore, water is a polar substance.
“Like Dissolves Like”: Polar substances dissolve in other polar substances. Nonpolar substances dissolve in other nonpolar substances. Example: Water dissolves methanol but not gasoline because methanol is polar and gasoline is nonpolar.
Concentration: how much solute is in a solution Dilute substance: not very much solute Concentrated substance: a lot of solute Unsaturated solution: a solution that can dissolve more solute Saturated solution: a solution in which no more solute can dissolve at the given temperature Solubility: Largest amount that will dissolve to produce a saturated solution.
Supersaturated solution (page 197): a solution that holds more solute than is allowed at a particular temperature. Molarity = Moles of solute Liters of solution Problem: What is the molarity of a solution of sugar water if there are 9 moles of sugar and 3 liters of water?