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.

pH pH is a measure of hydronium ions ◦ pH scale runs from  pH 0-7 is an acid; 7-14 is a base.  ph 7 is neutral Each single digit change of pH is a 10X 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 and 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!