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Section 2 Acids and Bases

Chapter 3 Chemical Compounds. Section 2 Acids and Bases. Section 2 Acids and Bases. Chapter 3. Acids and Their Properties. An acid is any compound that increases the number of hydronium ions , H 3 O + , when dissolved in water.

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Section 2 Acids and Bases

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  1. Chapter 3 Chemical Compounds Section 2 Acids and Bases

  2. Section 2 Acids and Bases Chapter 3 Acids and Their Properties • An acid is any compound that increases the number of hydronium ions, H3O+, when dissolved in water. • Hydronium ions form when a hydrogen ion, H+, separates from the acid and bonds with a water molecule, H2O, to form a hydronium ion, H3O+.

  3. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • Acids Have a Sour Flavor • Lemons, limes, and other citrus fruits are sour as a result of citric acid. • Taste, touch, or smell should NEVERbe used to identify an unknown chemical. • Many acids are corrosive, which means that they destroy body tissue, clothing, and many other things. • Most acids are also poisonous.

  4. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • Acids Change Colors in Indicators • A substance that changes color in the presence of an acid or base is an indicator. • This flask contains water and an indicator called bromthymol blue.

  5. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • When acid is added, the color changes from pale blue to yellow because of the presence of the indicator. • Another common indicator used in the lab is litmus. Paper strips containing litmus change color when acid is added.

  6. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • Acids React with Metals • Acids react with some metals to produce hydrogen gas. • When hydrochloric acid reacts with zinc metal, hydrogen gas is formed. • Equation: • 2HCl + Zn  H2 + ZnCl2

  7. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • In the reaction, zinc displaces hydrogen in the compound, hydrochloric acid. This displacement happens because zinc is an active metal. • Silver would not react -- not an active metal.

  8. Section 2 Acids and Bases Chapter 3 Acids and Their Properties,continued • Acids Conduct Electric Current • Acids are dissolved in water • Break apart • Form ions in the solution • The ions make it possible for the solution to conduct an electric current. • Example: car battery • The sulfuric acid in the battery conducts electricity to help start the car’s engine.

  9. Section 2 Acids and Bases Chapter 3 Acids and Their Properties, continued • Uses of Acids • Sulfuric acid is the most widely made industrial chemical in the world. It is used to make paper, paint, detergents, fertilizers and many other products. • Nitric acid is used to make fertilizers, rubber, and plastics. • Hydrochloric acid is used to make metal from their ores by separating the metals from the material with which they are combined.

  10. Section 2 Acids and Bases Chapter 3 Acids and Their Properties, continued • Hydrochloric acid is used in swimming pools to help keep them free of algae. Also found in your stomach, where it aids in digestion. • Citric acid and ascorbic acid (Vitamin C) are found in orange juice. • Carbonic acid and phosphoric acid help give soft drinks a sharp taste.

  11. Section 2 Acids and Bases Chapter 3 Bases and Their Properties • A base is any compound that increases the number of hydroxide ions, OH-, when dissolved in water. • Example, sodium hydroxide breaks apart to form sodium ions and hydroxide ions • NaOH Na+ + OH-

  12. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • Hydroxide ions give bases their properties. • Examples of bases include: • Soaps • Ammonia • Baking soda • Bleach • Detergents

  13. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • Bases Have a Bitter Flavor and a Slippery Feel • If you have ever tasted soap , you know the bitter taste of a base. It also has the slippery feel of a base. • Taste, touch, or smell should NEVERbe used to identify an unknown chemical. • Like acids, many bases are corrosive.

  14. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • Bases Change Color in Indicators • Like acids, bases change the color of an indicator. • Most indicators turn a different color in the presence of bases than they do in the presence of acids. • Example: • Red litmus paper changes to blue.

  15. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • When a base is added to bromthymol blue, it turns the indicator from pale blue to dark blue.

  16. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • Bases Conduct Electric Current • Bases increase the number of hydroxide ions, OH-, in a solution. • A hydroxide ion is actually a H atom and an O atom bonded together. • The extra electron gives the hydroxide ion a negative charge.

  17. Section 2 Acids and Bases Chapter 3 Bases and Their Properties, continued • Uses of Bases • Sodium hydroxide is a base used to make soap, paper, oven cleaners and products that unclog drains. • Calcium hydroxide, Ca(OH)2, is used to make cement and plaster. • Ammonia is found in many household cleaners and is used to make fertilizers. • Magnesium hydroxide and aluminum hydroxide are used in antacids.

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