Acids and Bases

Acids and Bases An acid is a substance that when added to water increases the concentration (amount) of hydrogen (H+) ions present. A base is a substance that when added to water increases the concentration (amount) of hydroxide (OH-) ions present.

Characteristics of Acids Acids tend to taste sour Are corrosive to metals and skin Contain hydrogen (H+) ions Turns blue litmus paper red React with metals and carbonates (CO3-2) Strong acids conduct electricity when dissolved in water

Examples of Common Acids Hydrochloric acid (muriatic) acid – HCl Sulfuric Acid (H2SO4) Acetic Acid (C2H4O2) Nitric Acid (HNO3) Citric Acid (C6H8O7)

Characteristics of Bases Bases tend to taste bitter Feel slippery Turns red litmus paper blue Contains hydroxide ions (OH-) React with fats/oils, so this makes them excellent cleaning agents Strong bases conduct electricity when dissolved in water

Examples of Common Bases Sodium bicarbonate (Na2CO3) Sodium hydroxide (NaOH) Potassium hydroxide (KOH) Calcium hydroxide Ca(OH)2 Magnesium hydroxide Mg(OH)2 Barium hydroxide Ba(OH)2 Ammonium (NH3)

pH Scale The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.

Indicators An indicator is a substance that helps identify if a substance is an acid or a base by changing colors.  Examples of indicators include: litmus paper, phenolphthalein, pH paper

Buffers Cells use buffers in our body to regulate blood pH values. Buffers resist changes in pH levels EX: If you exercise for long periods of time, the body uses up available oxygen and produces more carbon dioxide and hydrogen ions Lactic acid is produced that lowers blood pH Result: buffers like carbonate take the extra hydrogen ions out of the bloodstream to return pH values to normal