Explain a detergent molecule; describe how it has 2 distinctive parts. Daily Starter 1/6 Explain a detergent molecule; describe how it has 2 distinctive parts.

II. Strength of Acids & Bases Strong vs. Weak pH

Neutral Water Because [H+] = [OH-], pure water is neutral

Acidic In an acidic solution: [H+] > [OH-]

Basic In a basic solution: [H+] < [OH-]

Acids and bases can be classified as either strong or weak Strong: ionizes (dissociates) completely in H2O Weak: only partially ionizes (dissociates) in H2O

A. Strong vs. Weak Strong Acid/Base 100% ions in water strong electrolyte HCl, HNO3, NaOH, LiOH - + Weak Acid/Base few ions in water weak electrolyte HC2H3O2, NH3 - +

Strong Strong Acid: HCl  H+ + Cl- Strong Base: NaOH  Na+ + OH- Complete dissociation – all HCl and NaOH molecules break apart into ions. This is represented by a single-headed arrow.

WEAK Weak Acid: HCN H+ + CN- Weak Base: NH3 NH4+ + OH- Only some of the HCN and NH3 molecules break apart into ions. The reversible arrows represent a mixture of reactants and products in equilibrium.

B. pH Scale pH a measure of the concentration of H3O+ ions in solution measured with a pH meter or an indicator with a wide color range 7 INCREASING ACIDITY NEUTRAL BASICITY 14

pH of Common Substances B. pH Scale pH of Common Substances

ConcepTest Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? A B

ConcepTest Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? A B

Conjugate Acid/Base Conjugate acid or base is generally the product of the reaction (right side of rxn) **In-class work to show conjugate acid/base