Unit 2.4: pH, Oxidation, Reduction, and Catalysts

Bell Work Nov 4 Agenda: 1.Planner: 1.Late Work Due Nov 5 2.Unit 2 Test Tues Nov 11 3.Study Guide Due Tues Nov 11 2.Bell Work 3.Good Things 4.Notes 5.Indicator Demo 6.Finish Elements Video Bell Work: What are 2 thing you learned from the video yesterday?

Hunting the Elements Hunting the Elements- Video

Characteristics of Acids Acid: A substance that tastes sour and reacts with metals and carbonates (CO3) Examples: Hydrochloric Acid- HCl Nitric Acid Sulfuric Acid Citric Acid Acetic Acid (Vinegar) Citrus Fruits (oranges, lemons, limes)

Acids: Reactions with Metals and Carbonates Acids react with certain metals to produce hydrogen gas (H2) Acids are corrosive, meaning they “eat away” at materials Example: Mg + 2HCl -> H2 + MgCl2 Acids react with carbonates Vinegar and baking soda = acetic acid and sodium bicarbonate

Characteristics of Bases Base: a substance that tastes bitter and feels slippery When something is basic, it is often called “alkaline” Examples: Sodium hydroxide (NaOH) Ammonia Soap Detergent Baking Soda Most household cleaners

Indicators Indicators are substances that turn color based on how acidic or how basic something is Indicator Demo

[H+] and [OH-] In water, acids produce Hydrogen ions [H+] and an anion Therefore, an acid is any substance that produces H+ in water Example: HCl  H + +Cl - (in water) In water, bases produce hydroxide ions [OH-] and a cation Therefore, a base is any substance that produces [OH-] in water Example: NaOH  Na + + OH - (in water)

pH Scale The strength of acids and bases depends on the concentration of [H+] pH scale is numbered is neutral Low pH 0-6 tells you the concentration of H+ is high (acidic) High pH 8-14 tells you the concentration of H+ is low (basic) Use litmus paper to test pH Match color of paper to key

Acid-Base Reaction (aka: neutralization reaction) Called a “neutralization reaction” because an acid and a base added together with neutralize the pH and get to 7 Reaction Acid + Base  Water + Salt (ionic compound) Example: HCl + NaOH  H2O + NaCl

Bell Work Nov 5 Agenda: 1.Turn in all Late work 2.Planner: 1.Unit 2 Test Tues Nov 11 2.Study Guide Due Tues Nov 11 3.pH Lab Due Thurs 3.Bell Work 4.Good Things 5.pH Lab Bell Work:

Bell Work Nov 6 Agenda: 1.Turn in pH Lab 2.Planner: 1.Unit 2 Test Tues Nov 11 2.Study Guide Due Tues Nov 11 3.Catalyst Lab Due Monday 3.Bell Work 4.Good Things 5.Catalyst Lab Bell Work:

Catalyst A substance that speeds up a reaction but isn’t a reactant Biological catalysts are called enzymes Examples: Elephant Toothpaste and Genie in a Bottle used Potassium Iodide to speed up the decomposition reaction of hydrogen peroxide Lactase helps to break down Lactose in milk

Bell Work Nov 7 Agenda: 1.Planner: 1.Unit 2 Test Tues Nov 11 2.Study Guide Due Tues Nov 11 3.Catalyst Lab Due Monday 2.Bell Work 3.Good Things 4.Notes Bell Work:

Oxidation and Reduction Reactions Oxidation: A chemical reaction commonly involving oxygen An atom accepts electrons while combining with other elements. The atom giving away or losing electrons is said to be oxidized Exothermic Examples: burning of paper, rusting of ion Reduction: The opposite of oxidation The atom gaining reaction is said to be reduced Endothermic OIL RIG: Oxidation is losing, Reduction is gaining

Oxidation and Reduction Examples Batteries Rising of dough with yeast depends on oxidation of sugars to CO2 and H2O. The CO2 gives the rise. Tarnishing of silverware, 4Ag + 2H2S + O2  2Ag2S(black) + 2H2O Reduction of hypochlorite or perborate in bleach during oxidation of stains on clothes. Reduction of hydrogen peroxide to water on bleaching of hair blonde. Reduction of chlorine to chloride during oxidative destruction of pathogens in swimming pools or drinking water.