ACIDS AND BASES

What is an Acid? An acid is a substance that, when dissolved in water, produces positive hydrogen ions (H+). The more H + ions, the more acidic the solution.

Properties of Acids 1. Acids have a sour taste.

Properties of Acids 2. Acids are corrosive – having the ability to “eat away” at metals like iron, zinc, and magnesium. - Hydrogen gas is produced.

Properties of Acids Example: calcium carbonate (CaCO3) or limestone 3. Acids react with carbonates to produce carbon dioxide. - Carbonates are ions containing carbon and oxygen atoms bonded together. Example: calcium carbonate (CaCO3) or limestone

Properties of Acids 4. Acids turn blue litmus paper red.

Some Uses of Acids Acetic Acid (C2H4O2) – Vinegar Ascorbic Acid (C6H8O6) – Vitamin C Citric Acid (C6H8O7) – found in lemons, limes, oranges, and sour candies

Some Uses of Acids Hydrochloric Acid (HCl) – used in the production of plastics, household cleaning products, and food additives Sulfuric Acid (H2SO4) - used in the production of fertilizers, paints, and plastics

What is a Base? A base is a substance that, when dissolved in water, produces negative hydroxide ions (OH-).

Properties of Bases 1. Bases have a bitter taste.

Properties of Bases 2. Bases have a slippery feel.

Properties of Bases 3. Bases turn red litmus paper blue.

Some Uses of Bases Ammonia (NH3) – used to manufacture dyes, explosives, plastics, and household cleaning products Calcium Hydroxide Ca(OH)2 – used to make mortar or plaster Sodium Hydroxide (NaOH) – used to manufacture soap and paper

Measuring pH The pH scale is a range of values from 0 to 14. It expresses the concentration of hydrogen ions in a solution. A low pH tells you that the concentration of hydrogen ions is high. A high pH tells you that the concentration of hydrogen ions is low.

Measuring pH A change of 1 pH unit represents a tenfold change in the acidity of the solution. Example: If one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.

pH Indicators A pH indicator is a substance that changes color depending on the pH of the solution with which it is mixed. - They are often made from plant extracts.

Measuring pH with an Indicator

Acid-Base Reactions A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or as basic as the individual starting solutions.

Acid-Base Reactions

Acid – Base reactions Each salt listed in this table can be formed by the reaction between an acid and a base.