1. Acids and Bases Chapter 23.4

2. Properties of Acids Sour taste Acids turn litmus paper from blue to red Neutralize a base Disassociate in water to form H+ ions Low PH Strong acids have molecules that all disassociate in water. (if you pour HCl into water, there is no HCl left. All of it disassociates into H+ ions and Cl- ions. Vinegar is a weak acid. Some of its molecules stay together when it is added to water

3. Properties of Bases Bitter taste Turns litmus paper from red to blue Neutralizes an acid Slippery feel High PH Disassociate in water to form OH- ions NaOH is a strong base. It completely disassociates in water to form Na+ and OH- ions. NH 3 is a weak base. Some of it remains as ammonia in water (gets the O for the OH- from the water).

4. PH Values 1-14 High end (8-14) = a base, lots of OH- ions present (alkaline) Low end (1-6) = an acid, lots of H+ ions present An acid neutralizes a base, and a base neutralizes an acid. PH of 7 = pure water (usually distilled –no other ingredients in it but water)

5. PH values Lemon juice 2 Vinegar3 Soda water4 Baking soda8.5 Bar of soap10 Ammonia11 The higher the number the stronger the base The lower the number the stronger the acid

6. PH Indicator Detects the PH of a liquid Litmus paper changes color Phenothathene changes to pink when detects a base in a solution Red cabbage boiled

7. AAA Always add acid to any liquid Put liquid in the container, then add the acid to it. If you do it the other way around, the acid might splatter on you add the liquid to it. Very dangerous, burns terrible!

8. Titration Diluting an acidic solution to find out many grams of acid are in the solution 1. put acid in flask 2. put base in burette (big graduated eye dropper) 3. add PH indicator to flask of acid (phenothelene). Phenothelene is clear in an acid but turns red when it detects a base. 4. Slowly drip base into flask 5. the first hint of red = end point, STOP the drip! Your acidic solution is now basic. Read how much base you used.

9. To find how many grams of acid were in the solution that you started with Lets say that you used 2ml of base to dilute the acid (what was used from the burette). Use the conversion method. 1. calculate grams per molecule of base (NaOH = Na = 23g + O = 16g + H = 1g. All of them together = 23+16+1 = 40g per molecule Calculate grams per molecule of acid (HCl = H =1g + Cl = 35g. Together 1+35 = 36g per molecule Balance the reaction NaOH + HCl Na + + - Cl + H 2 0 balanced, so you need 1 molecule of acid for every molecule of base

10. 2. determine end point = how much base was used in ml. 3. calculate from ml. of base to grams of base to grams of the acid Example Suppose you used 2 ml. of the base and the acidic solution began to turn red. That is the end point I tell you that the base solution contains 8g of actual base per liter of solution (that is the concentration of the basic solution).

11. 2ml 1l 8g(base) 1 molecule 1 1000ml 1l 40g(base) Used 8grams 40grams of base of base base per molecule per liter of solution 36g(acid) 1molecule =.0144 = 1.4 x 10 -2 = 1 x 10 -2 sig.figs=1

12. Electrolytes Ions in a solution conduct a current (electrical). Acids and bases disassociate in water to form ions Non-electrolytes do not disassociate in water to ions (like sugar). Sugar-water does not conduct a current and is neither an acid or a base. Salt will disassociate in water to form ions, so ionic compounds, molecules, acids and bases can act like electrolytes to disassociate in water and conduct a current. So, don’t drop anything electrical in water in case ions are present in it.