Section 4: Acids and Bases in Solution

• Objectives:describe the ions

formed when acids and bases are dissolved in water

describe the pH scale and tell how it is used

explain what happens in a neutralization reaction

Acids in Solutions

An acid is any substance that produces hydrogen ions (H+) in water

Bases in Solution

A base is any substance that accept hydrogen ions such as those that produce hydroxide ions (OH+) in water.

Strength of Acids and Bases

Strength of an acid or base refers to how well an acid or base produces ions in water. Acids produce hydrogen ions (H+) while basesproduce hydroxide ions (OH-).

Measuring pH

The pH scale is a range of valuesfrom 0-14. It is a measure of concentration of hydrogen ions.

pH of 1 = very high hydrogen ionspH of 14 = very low hydrogen ions

Acid Rain

Many industrialized countries use coal as their main source of energy.As coal burns, so does the sulfur that it contains. The sulfur dioxideoxidizes and combines with moisture in the air to form sulfuric aciddroplets. In addition, nitrogen oxide from car exhaust combine withMoisture to make dilute nitric acid.

Acid rain can create many problems on earth including:

And destruction or damage of lakes and streams:

Common Antacids

Antacid Active Ingredients

Tums CaCO3 (calcium carbonate), MgCO3 (magnesium carbonate), Mg2Si3O8 (Magnesium trisilicate)

Maalox Suspension of Mg(OH)2 (magnesium hydroxide and Al(OH)3 (aluminum hydroxide) in water

Rolaids CaCO3 (calcium carbonate) and Mg(OH)2 magnesium hydroxide)

Alka-Seltzer Ca(H2PO4)2 (calcium dihydrogen phosphate), NaHCO3 (sodium bicarbonate), citric acid, and aspirin.

Acid-Base Reactions

Sometimes an acid-base reaction can produce a neutral solution.

Products of Acid-Base Reactions

A neutralization reaction produces water and a salt.

Common Salts and Their Uses

Salt Name Formula Made From

Base + Acid

Uses

Sodium chloride

NaCl NaOH + HCl Seasoning/food preservative

Sodium bicarbonate

NaHCO3 NaOH + H2CO3Baking soda

Calcium chloride

CaCl2 Ca(OH)2 + HCl Drying agent/absorbs moisture

Potassium nitrate

KNO3 KOH + HNO3fertilizer