Chapter 21 Neutralization Neutralization Reactions Salts in Solution
Common Indicators IndicatorColor ChangepH Range Methyl RedRed - Yellow4.3 – 6.2 Phenol RedYellow - Red6.9 – 8.2 Alizarin YellowYellow - Pink10.0 – 12.0 PhenolpthaleinClear - Pink Congo RedBlue - Red3.0 – 5.2 Bromothymol BlueYellow - Blue6.0 – 7.5
Acid-Base Reactions Acid + Base Salt + Water Salt – Compounds made up of anions from an acid and cations from a base
Neutralization Reaction Strong Acid + Strong Base Salt and Water The number of hydronium ions must equal the number of hydroxide ions A reaction of a weak acid and weak base do not usually produce neutral solutions
Salts Ammonium Sulfate – Fertilizer Calcium Chloride – Road Salt Potassium Chloride – Sodium Free Salt Substitute Silver Nitrate - Cauterizing Agent Sodium Hydrogen Carbonate - Antacid
Titration Process of adding a known amount of a solution of known concentration to determine the concentration of another solution End Point – the point where the indicator changes color
Ch 21.2 Salts in Solution Salt Hydrolysis Buffers Common Ion Effect
Salt Hydrolysis Reaction of a strong acid and a weak base or a strong base and a weak acid The salt may be acidic or basic, not neutral (strong acid – strong base reaction) CH 3 COO - (aq) + H 2 O (l) CH 3 COOH (aq) + OH - (aq) Hydrolysis – splits a hydrogen off a water molecule
Summary Strong Acid + Strong Base Neutral Solution Strong Acid + Weak Base Acidic Solution Weak Acid + Strong Base Basic Solution
Buffer The pH remains relatively constant with the addition of small amounts of acid or base Made up of a solution of a weak acid and its salt or a weak base and its salt
Human Blood Two main buffers to keep pH – Carbonic acid-hydrogen carbonate buffer system – Dihydrogen phosphate – monohydrogen phosphate buffer system
Common Ion Effect The lowering of solubility of a substance by the addition of a common ion