Acids and bases
- 1. Acids and Bases Holt: Chapter 15, Sections 2 and 3 Fusion: Lesson 6 (starts on p 190)
- 2. Acids • An acid is any compound that increases the number of hydronium ions (H+) when dissolved in water • Acids typically begin with hydrogen, H. • Examples: H2SO4, HCl
- 3. Acids and their properties • Sour taste ex: citric acid (we NEVER taste in a lab) • Corrosive- they destroy body tissue, clothing, and many other things • Can be poisonous • Reacts with some metals to produce hydrogen gas • Can conduct electric current ex: battery acid • Acid turns blue litmus paper red • What is litmus paper? • An indicator. An indicator is a substance that changes color in the presence of an acid or base. Litmus paper is NOT the only indicator.
- 4. Uses of acids • H2SO4 is sulfuric acid. Is the most widely made industrial chemical in the world. Used to make paper, paint, detergent and fertilizers. • Used in swimming pools to kill algae • HCl used in your stomach to digest food • Citric acid and ascorbic acid are in orange juice • Carbonic acid and phosphoric acid are in soda
- 5. Bases • A base is any compound that increases the number of hydroxide ions, (OH- ) when dissolved in water. • Most bases end with OH- • Examples: NaOH, Ca(OH)2
- 6. Bases and their properties • Bitter taste • Slippery feel • Many bases are corrosive • Bases turns red litmus paper blue • Conduct electric current
- 7. Uses of bases • NaOH (sodium hydroxide) is used to make soap and paper, oven cleaners and products to unclog drains • Ca(OH)2 (calcium hydroxide) is used to make cement and plaster • Ammonia is found in household cleaners and to make fertilizer • Magnesium hydroxide and aluminum hydroxide are used in antacids to treat heartburn.
- 8. Strengths of acids and bases Acids • Strong acids have additional H+ • All of the acid’s molecules break apart • Examples of strong acids: H2SO4 (sulfuric acid), H2CO3 (carbonic acid), H3PO4 (phosphoric acid) Bases • Strong bases have additional OH- • All of the base’s molecules break apart • Examples of strong bases: Ca(OH)2 (calcium hydroxide), Ba(OH)2 (barium hydroxide)
- 9. Neutralization • The reaction between acids and bases is a neutralization reaction. • React to form water (which is neutral) and a salt. • A salt is an ionic compound formed from the positive ion of a base and the negative ion of an acid. • Salts are a large group of compounds; not just table salt!
- 10. pH scale • Indicators are used to identify whether a solution contains an acid or a base. • A pH scale is used to describe how acidic or how basic a solution is. • pH is a measure of the hydronium ion concentration. • pH of 7 is neutral; pure water • pH of less than 7 is acidic • pH of greater than 7 is basic
- 11. pH values of common materials