- 1. Solutions IB Chemistry: Chapter 1 Section 1.5
2. What parts make up a solution? Solutionis a mixture of two components.1. Solute: less abundant component, the substance being dissolved2. Solvent: more abundant component, the dissolverSolutions in water are called aqueous (aq). 3. Concentration As more and more solute gets dissolved, the solution becomes more concentrated.When the solvent can no longer dissolve any more solute, it is saturated. (If less solute is dissolved, unsaturated.)Solution can dissolve more solute than usual under particular circumstances supersaturated. 4. Molarity Molarityis a term we use to describe concentration.= mol/dm3, Molarity = moles (n) of solute dissolved in 1 dm3 of solution.Mis the molarity of 2.98g of NaCO3 in 500cm3 of solution? What 5. Dilutions Sometimes, we need a diluted solution for a particular procedure.In order to dilute, you add water to a more concentrated solution.The equation we use to determine how much concentrated solution we need is: M1V1=M2V2 6. Types of Mixtures Classifiedby: Size of the particles Whether they exhibit the Tyndall effect 7. Types of Mixtures Solution: Particlesare evenly distributed and do not separate on standing No Tyndall Effect Example: food coloring and water mixture 8. Solution Example Notice how you cannot see a distinction between solute and solvent. It is the same throughout the solution. 9. Types of Mixtures Suspensions: Particlesare not evenly distributed. Particles are suspended but will eventually settle into layers Exhibits Tyndall Effect Examples: Dirt and water mixture 10. Suspensions The larger particles in a suspension settle out over time. Particles are only physically combined. 11. Types of Mixtures Colloids: Particlesare not evenly distributed. Particles are suspended but will eventually settle into layers Exhibits Tyndall Effect Examples: milk 12. Colloids Looks like a solution to the naked eye. Particles are suspended. The particle size is the in betweener, larger than a solutions particles but smaller than a suspensions particles. 13. What is this Tyndall effect? Lightscattering by particles. Foundin colloids and suspensions, but not solutions. 14. Tyndall Effect 15. Hydrates Hydratesare ionic compounds that have water molecules absorbed into the crystal lattice. Hydratesare still solid, just have certain amounts of water attached to the ions. Anexample of a hydrate is Copper (II) Sulfate pentahydrate: CuSO4 5H2O 16. Hydrates An example of a hydrate is: CuSO4 5H2O This means that for every 1 unit of copper sulfate, there are 5 units of water. Or, for every 1 mole of copper sulfate there are 5 moles of water. Solve for the molar mass. (The dot does not mean multiply, just add the mass of water to mass of copper sulfate.) 17. Properties of Solutions: Dissociation When Ifa solute dissolves, the solute molecule is surrounded by water molecules.the solute is ionic, than the ions separate and are surrounded by water molecules. Example:NaCl Na+ + Cl- 18. Model of NaCl dissolving in water Na+ClNa+ClNa+Cl-Na+Cl-Cl-Na+Na+ 19. Dissociation Continued Because of this, ionic substances have more of an effect on the boiling point and freezing point than a covalent bond (something that is not ionic). C6H12O6 (s) C6H12O6 (aq) NaCl(s) Na+ (aq) + Cl-(aq) CaCl2 (s) Ca2+ (aq) + 2Cl-(aq)(1 particle being dissolved, not ionic) (2 particles being dissolved, ionic) (3 particles being dissolved, ionic)CaCl2 will have the largest effect (higher melting/boiling pts) and glucose the least effect (lower melting/boiling pts). 20. Ability to Conduct Electricity If ions are present in solution, it will conduct eletricityall ionic substances will conduct electricity when dissolved. Ex: Tap water, salt waterSolutes that conduct electricity when dissolved are called electrolytes. 21. Electrolytes Importanceof electrolytes: The movement of calcium ions allows muscles to contract and relax Presenceof sodium and potassium ions allow your nerve cells to respond to stimuli. 22. STRONG vs. weak Electrolytes Strength depends on number of ions in solutionMore ions = stronger electrolyte, Fewer ions = weaker electrolyteFor strong electrolytes, increasing concentration increases conductivityWeak electrolytes, increasing concentration does not effect conductivity 23. Think about it!!! Forstrong electrolytes, increasing concentration increases conductivity Weakelectrolytes, increasing concentration does not effect conductivityWHY???? 24. Colligative Properties 1. Boiling point of the solvent elevates 2. Freezing point is loweredVapor pressure is lowered, fewer molecules of solvent are escaping to the gas phase when a solute is present. The solvent molecules cannot escape because they are busy keeping the solute dissolved. 25. Salting the Roads! Rocksalt (CaCl2) is used to keep the roads from freezing in the winter. Ever wonder why that happens????