1. Solutions, Acids and Bases

2. Solution Formation A solution is a homogeneous mixture of two or more substances (Unit 1) A solution has two parts: – Solute – Solvent

3. Solutes and Solvents A solute is a substance whose particles are dissolved in a solution A solvent is the substance in which the solute dissolves

4. Solutes and Solvents cont. Example: In a solution of seawater, salt is the solute and water is the solvent - Salt dissolves in water

5. Dissolving Substances can dissolve in three ways: Dissociation Dispersion Ionization

6. Dissociation Dissociation is the process in which an ionic compound separates into ions as it dissolves

7. Dispersion Dispersion is the breaking apart of a compound into small pieces – Sugar in water

8. Ionization The process in which neutral molecules gain or lose an electron – Ions in the solution are formed by the reaction of the solute and solvent

9. Properties of Liquid Solutions Liquid solutions share three physical properties Conductivity Freezing Point Boiling Point

10. Conductivity Conductivity is an object’s ability to conduct electricity HCL gas is a poor conductor of electricity, however HCL in liquid form easily conducts an electric current – Due to ionization of the HCL in water

11. Freezing and Boiling Points Freezing point: The temperature at which a substance freezes and becomes a solid Boiling Point: The temperature at which a substance begins to boil, creating a gas

12. Freezing and Boiling Points cont. Fresh water freezes at 0 degrees Celsius Saltwater freezes at -6 degrees Celsius – With a 10% salt solution – The more salt you add, the lower the freezing point will be

13. Factors That Affect Rates of Dissolving Surface Area: The larger the surface area, the quicker the substance dissolves Stirring: Stirring a solution will speed up dissolving Temperature: An increase in temperature increases the dissolving rate

14. Acids and Bases A solution can either be an acid or a base depending on which properties a solution takes on as well as by indicating an acid or a base by using the pH scale

15. Identifying Acids An acid is a compound that produces hydronium ions (H 3 O + ) when dissolved in water HCL + H 2 O  H 3 O + + Cl -

16. Properties of Acids Sour taste Reactivity with metals Ability to produce color changes in indcators

17. Sour Taste: Foods that taste sour often contain an acid - Citrus fruits (lemons, limes, etc.) naturally contain citric acid Reactivity with metals: Acids may dissolve weak metals Color Change: On a pH indicator, acids will turn a certain color

18. Bases A base is a compound that produces hydroxide ions (OH - ) NaOH  Na + + OH -

19. Properties of Bases Bitter taste – Objects that taste bitter contain a base Slippery Feel – Bases often have a slippery feel to them Color Change – Bases change a certain color when tested for pH levels

20. Strengths of Acids and Bases The strength of an acid or base can be indicated by the pH scale

21. pH Scale A scale from 0-14 – 0 = most acidic – 14 = most basic Pure water has a pH of 7

22. Acid, Base, or Neutral? Lemon Juice? Milk? Ammonia (found in household cleaners)?