Chapter 9 Acids and Bases Principles of Earth

Chapter 9: Acids and Bases Principles of Earth and Physical Sciences Mr. Taylor Rainier Jr/Sr High School

Acids �Acids ◦ taste sour ◦ cause indicators to change colors �For example they cause blue litmus to change to red. ◦ conduct electricity ◦ are corrosive and damage materials �Acids form hydronium ions (H 3 O+)

Acids �Strong acids ionize completely in water. ◦ This makes them conduct electricity. �This makes them “electrolytes”. ◦ The more they ionize, the stronger the acidity. �Sulfuric, hydrochloric, and nitric acids are strong. �Acetic, citric, and formic acids are weak.

Bases �Bases: ◦ ◦ have a bitter taste feel slippery conduct electric currents cause indicators to change colors �For example bases cause red litmus to change to blue. ◦ can damage skin �Bases - form hydroxide ions (OH )

Bases �Strong bases ionize readily in water and form many hydroxide ions. ◦ Potassium, sodium, and calcium hydroxides are strong bases ◦ Ammonia and baking soda are weak bases.

p. H �p. H is a measure of hydronium ions ◦ p. H scale runs from 0 -14. �p. H 0 -7 is an acid; 7 -14 is a base. �ph 7 is neutral �Each single digit change of p. H is a 10 X increase/decrease in hydronium ion concentration.

Acid-Base Reactions �A reaction between an acid and a base is called a neutralization reaction. �A reaction of a strong acid and a strong base forms water and a salt. ◦ Salts are combinations of positive and negative ions (Na+ and Cl-; K+ and I-, etc) �Resulting products may be acid, base, or neutral.

Salts �Almost any combination of cations and anions will form a salt. ◦ Salts are used in the kitchen (salt, baking soda, detergents), fire extinguishers, fertilizers, film photography, and many other uses. ◦ Some salts are critical to maintaining good health �Sodium (Na+), Potassium (K+), Calcium (Ca+2), Phosphate (PO 4 -3), and others.

Household uses of acids, bases, and salts �Soaps ◦ Like dissolves like; oily products cannot be cleaned by water alone. Soaps are large molecules that have a polar end a non-polar end. The non-polar end surrounds the oil; the polar end dissolves in water. �Detergents are much the same but work better in “hard” water (has dissolved minerals in it).

Household uses of acids, bases, and salts �Ammonia is a useful household cleaner. �Bleach ◦ Used as a disinfectant (kills germs). ◦ Used to remove stains. It doesn’t remove the stain chemical, it just removes the color. �Acids are useful antioxidants to keep fruit fresh ◦ Vitamin C (ascorbic acid) and citric acid

Household uses of acids, bases, and salts �Acidic solutions can tenderize meat ◦ Vinegar or lemon juice �Curdling of milk in yogurt and cheese is often achieved with lactic acid. �Drain cleaners are strong bases.

�That’s all for now!