Acids and Bases

Your standard SPI 0807.9.12 Identify the basic properties of acids and bases.

Key Words Acid Ion Base pH scale Neutral

Acids and Bases Acids and bases have distinct characteristics. We use them every day. Many substances are classified as an acid or a base. A substance is an acid or a base depending on the molecules that make it up and what it releases when it is dissolved in water.

Ions An ion is an atom or group of atoms that has a positive or negative charge because it has lost or gained electrons. Ions are released when acids or bases are dissolved in water.

Acids An acid is a substance that produces hydrogen ions (H+) in a water solution, or in other words, when it is dissolved in water. Acids can easily be identified by their chemical formulas. Acids generally have formulas that start with hydrogen such as HCl.

Properties of Acids Always taste sour-such as a lemon which contains citric acid. Strong acids are corrosive, which means they can eat through plastics, clothing, certain metals, and even skin. Some acids dissolve proteins. HCl in your stomach digests food. Can react with certain metals to produce hydrogen gas.

Litmus paper in acids will turn/stay red. When an acid dissolves in water, H+ ions interact with water molecules to form hydronium ions H30+ Can conduct electricity

Common Acids Acetic Acid, CH3COOH Vinegar Acetylsalicylic Acid Aspirin Carbonic Acid, H2CO3 Carbonated Drinks Hydrochloric Acid, HCl Gastric Juices

Nitric Acid, HNO3 Fertilizers Sulfuric Acid, H2SO4 Manufacture fertilizers Phosphoric Acid, H3PO3 Fertilizers, detergents & soft drinks

Bases Base- a substance that forms hydroxide ions (OH-) in water. Opposite of acids.

Brain Break with Brain Pop http://www.brainpop.com/science/matterandchemistry/acidsandbases/

Properties of Bases Litmus paper in bases will turn/stay blue. Many end in OH. Solids Feel slippery Taste bitter Strong bases are as corrosive as strong acids and can eat through many materials. That is why strong bases such as lye are used to unclog drains, for example. Can conduct electricity.

Common Bases Ammonia, NH3 Cleaner, fertilizer Aluminum Hydroxide, Al(OH)3 Antacid Magnesium Hydroxide,Mg(OH)2 Milk of Magnesia Sodium Hydroxide, NaOH Soap, Oven Cleaner & Drano

Strength of Acids and Bases Strong Acid- An acid that completely breaks down in solution…releasing H+ ions Ex: Hydrochloric, Sulfuric & Nitric Acid Weak Acid- An acid that partly breaks down in solution. Ex: Acetic and Carbonic Acid

Strong Base- A base that completely breaks down in a solution…releasing OH- ions. Ex: Ammonia Weak Base- A base that partly breaks down in a solution. Ex: Sodium hydroxide

The pH Scale http://www. brainpop The pH scale is used to identify how acidic or basic a substance is. It is numbered from 0 to 14.

In an acid, the concentration of H+ ions is greater than the concentration of OH- ions. The lower the pH value, the stronger the acid. The opposite is true for bases. A substance that has a pH greater than 7 is a base and is described as alkaline. pH means “potential for Hydrogen”

When a liquid has a pH of 7, it is said to be neutral. The concentration of H+ ions equals the concentration of OH- ions. Pure water has a pH of 7 and is neutral. Neutral liquids do not have the properties of either acids or bases.

Neutralization reactions When acid and base solutions are mixed in the right proportions, the positive ions from the base combine with the negative ions from the acid. A new ionic compound forms and water is one of the products. This is a neutralization reaction.

Acid or Base? Classify the following pH values: pH = 1 pH = 13 pH = 8 pH = 3 pH = 6 pH = 10

Classify the following pH values: Acid or Base? Classify the following pH values: pH = 1 pH = 13 pH = 8 pH = 3 pH = 6 pH = 10 Acid Base 8th Grade