Unit 2.4: pH, Oxidation, Reduction, and

Catalysts

Bell Work Nov 4• Agenda:1.Planner:

1. Late Work Due Nov 52. Unit 2 Test Tues Nov 113. Study Guide Due Tues Nov 11

2.Bell Work3.Good Things4.Notes5.Indicator Demo6.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 waterExample:

NaOH Na+ + OH- (in water)

pH Scale

• The strength of acids and bases depends on the concentration of [H+] • pH scale is numbered 0-14• 7 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 work2.Planner:

1. Unit 2 Test Tues Nov 112. Study Guide Due Tues Nov 113. pH Lab Due Thurs

3.Bell Work4.Good Things5.pH Lab

• Bell Work:

Bell Work Nov 6• Agenda:1.Turn in pH Lab2.Planner:

1. Unit 2 Test Tues Nov 112. Study Guide Due Tues Nov 113. Catalyst Lab Due Monday

3.Bell Work4.Good Things5.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 112. Study Guide Due Tues Nov 113. Catalyst Lab Due Monday

2.Bell Work3.Good Things4.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.