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Chapter 8

Chapter 8. Acids & Bases. Identifying acids . A . Identifying Acids a . An acid is a compound that produces hydronium ions (H 3 O + ) when dissolved in water.

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Chapter 8

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  1. Chapter 8 Acids & Bases

  2. Identifying acids A. Identifying Acids a. An acid is a compound that produces hydronium ions (H3O+) when dissolved in water. b. Some general properties of acids include sour taste, reactivity with metals, and ability to produce color changes in indicators.

  3. Sour Taste c. Sour Taste 1. Many of the foods that you eat that taste sour contain acids. Although you acids are in the foods we eat, you should never test an acid by tasting it.

  4. Reactivity d. Reactivity With Metals 1. The reaction between an acid and a metal is an example of a single replacement reaction. 2. When you cover foods that contain tomatoes with aluminum foil, the foil may turn dark, develop small holes, and the food may have a metallic taste. Tomatoes contain citric acid, which reacts with metals such as aluminum.

  5. Color Change e. Color Changes in Indicators 1. An indicator is a substance that changes color in the presence of an acid or base. 2. A commonly used indicator is litmus paper. 3. Blue litmus paper turns red in the presence of an acid.

  6. Bases B. Identifying Bases a. A base is a compound that produces hydroxide ions (OH-) when dissolved in water. b. Some general properties of bases include bitter taste, slippery feel, and ability to produce color changes in indicators. Bases usually do not react with metals.

  7. Taste c. Bitter Taste 1. Many of the foods that you eat that taste bitter are bases. 2. Examples of these would be unsweetened chocolate and liquid medications. Many times fruit flavorings are added to mask the taste of basic solutions.

  8. Feel d. Slippery Feel 1. Many items that you touch on a daily bases feel slippery. This slippery feel is due to the product containing bases. 2. Examples of these would be soap and many cleaning products. Also, rocks that feel slippery are due to water dissolving compounds trapped in the rocks which produce a basic solution.

  9. Color e. Color Change in Indicators 1. Bases turn red litmus paper blue. The litmus paper will change back to red if you drop an acidic solution on it.

  10. Neutralization & Salts C. Neutralization and Salts a. Neutralization is a reaction between an acid and a base. b. During a neutralization reaction between an acid and a base water and salt are produced.

  11. Protons D. Proton Donors and Acceptors a. Acids can be defined as proton donors, and bases can be defined as proton acceptors. 1. Acids lose protons. 2. Bases accept protons. 3. Water is neutral. In a reaction water can act like an acid or a base. In some cases water will accept a proton and be a base, and in some cases water will lose a proton and be an acid.

  12. Strengths E. Strength of Acids and Bases a. One way to describe the strength of an acid or base is to determine the concentration of hydronium or hydroxide ions present in a solution. Another way is to describe how readily those hydronium ions or hydroxide ion formed.

  13. pH Scale F. The pH Scale a. Chemists use a number scale from 0 to 14 to describe the concentration of hydronium ions in a solution. b. A pH of 7 indicates a neutral solution. c. A pH less than 7 indicates an acid. d. A pH greater than 7 indicates a base.

  14. Electrolytes G. Electrolytes a. An electrolyte is a substance that ionizes or dissociates into ions when it dissolves in water. b. The resulting solution can conduct electric current. c. Strong acids or bases are strong electrolytes because they dissociate or ionize almost completely in water.

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