Chapter 8 Acids, Bases, and Salt Section 1 Acids, Bases, and pH p. 256

Compare acids and bases Understand the set up of the pH scale Objectives Compare acids and bases Understand the set up of the pH scale

Acids And Bases Have Two Different Faces I. Acids- any compound that increases the number of hydronium (H3O+) ions when dissolved in water (they must ionize) A. Characteristics 1. Sour taste 2. Turn blue litmus paper red- blue to red, acid (litmus is an indicator) 3. Equation usually starts with an H (HCl, H2SO4)

B. Strong acids completely ionize and form electrolytes 1. Electrolyte- substances that conduct electricity when dissolved in water C. Weak acids form weak electrolytes D. Concentrated acids can be very dangerous – a diluted solution is safer

II. Bases- any compound that increases the number of hydroxide (OH-) ions when dissolved in water A. Characteristics 1. Bitter or soapy taste 2. Solutions feel slippery 3. Turn red litmus paper blue 4. Strong bases end in OH, weak will form OH when dissolved in water

B. Strong bases- ionic compound that contains a metal and OH- ion 1. When dissolved in water they dissociate completely 2. Attacks living tissue rapidly – when concentrated, can be more dangerous than acids C. Weak bases form OH- ions when dissolved in water Acids & Bases

Each step in the scale is a power of 10 increase/decrease in strength III. pH – Indicates concentration of H30+ ions (think percent hydronium) pH is an indication of moles/L of hydronium [1x10-7 mol/L is a pH of 7] The exponent of the concentration is the pH Each step in the scale is a power of 10 increase/decrease in strength Developed to test the acidity of beer

Acids Balance of Ions Bases  More H30+ More OH-  Acids Balance of Ions Bases 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Battery Acid Antacids Hand Soap Stomach Acid Citric Acid Coffee Pure Water Ammonia Drain Cleaner

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