1. Copyright © Houghton Mifflin Company.All rights reserved. Presentation of Lecture Outlines, 2–1 Welcome ! Review : Stoichiometry Today: Acid/base chemistry, thermodynamics

2. Stoichiometry Using a balanced chemical equation to determine how much reactant or product is consumed or produced in a chemical reaction. 2 H 2 (g) + O 2 (g)  2 H 2 O (l) –How many moles of H 2 O are produced from the reaction of 2 moles of H 2 ? –How many moles of O 2 are required to produce 4 moles of H 2 O? Chemical equation = recipe

3. Determine the % Acetic Acid in Vinegar using Eggshells… Mass of eggshell reacted. Moles of CaCO 3 reacted. Mole ratio (CaCO 3 : HC 2 H 3 O 2 ). Moles of Acetic acid. Grams of Acetic acid in sample. Experimental percentage. Accepted percentage. Percentage error. Copyright © Houghton Mifflin Company.All rights reserved. Presentation of Lecture Outlines, 2–3

4. Acid: A substance that releases H+ ions in an aqueous solution “aqueous” means: water

5. Characteristics of Acids: Acids have a sour taste Acids react with metals Acids contain Hydrogen Many are poisonous and corrosive to skin H

6. Strong Acids (break down completely to give off many H+ ions)

7. Weak Acids (only partially breaks down, gives less H+)

8. Acids and Bases Acids: Some common acids in our daily life: Ethanoic Acid, CH 3 COOH: found in vinegar, tomato juice Citric Acid, C 6 H 8 O 7 : found in citrus fruits Lactic Acid: found in sour milk, yogurt Tannic Acid: Found in tea Tartaric Acid: Found in grapes What about those commonly found in our lab? Hydrochloric acid, HCl Sulfuric Acid, H 2 SO 4 Nitric Acid, HNO 3 Which of these is found in batteries? Sulfuric Acid

9. Base: A substance that releases OH- ions in an aqueous solution

10. Characteristics of Bases: Bases usually taste bitter Bases feel slippery Bases contain hydroxide ions STRONG bases are also poisonous and corrosive to skin OH -

11. Strong BasesThe Formulae Lithium hydroxide Sodium hydroxide Potassium hydroxide Rubidium hydroxide Caesium hydroxide Barium hydroxide Calcium hydroxide Strontium hydroxide LiOH NaOH KOH RbOH CsOH Ba(OH) 2 Ca(OH) 2 Sr(OH) 2 Common Bases: (Hydroxides of Group 1 and Group 2 Metals are STRONG) All others are WEAK

12. Some bases (VERY FEW) don’t have OH- Most commonly: ammonia NH3

13. Reactions between acids and bases When and acid and a base react with each other, the characteristic properties of both are destroyed. This is called neutralization.neutralization

14. Reactions between acids and bases General formula for acid base reaction: Acid+Base→ H2OH2O+ Salt “Salt” means any ionic compound formed from an acid/base reaction NOT JUST NaCl !! Neutralization Reaction Animation

15. Neutralization HCl + NaOH → H 2 O + NaCl acidbase water salt

16. Neutralization Another Example HNO 3 + KOH → H 2 O + KNO 3 H OH K NO 3 acidbase water salt

17. Indicators An indicator is a compound that will change color in the presence of an acid or base Universal indicator (pH paper) Used for the full pH range Red Litmus-Turns blue in base Blue Litmus-Turns red in acid Phenolphthalein-Turns pink in base

18. pH pH stands for “potential hydrogen” and is a measure of how many H+ ions there are in solution. The MORE H+ there are, the LOWER the pH will be. pH = - log [H + ]

19. pH Scale Shows the range of H+ concentrations High H+ concentrationLow H+ concentration Virtual demonstration - Detecting acid/base

20. Activity – Red Cabbage indicator Chemists use indicators to test whether a substance is an acid or a base. Indicators work by turning a distinctive color in the presence of an acid or a base. You can make your own indicator from red cabbage. You can also make indicators from the juice of elderberries, blackberries, radish skins, apple skins, or cherries.