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ACIDS, BASES AND SALTS

ACIDS, BASES AND SALTS. C. Smith. ACIDS, BASES AND SALTS. 1. Acids are defined as substances that produce hydronium ions. An acid is a substance that releases hydrogen ions when it dissociates in water. HCl dissociates in water as follows: HCl ---> H + + Cl -

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ACIDS, BASES AND SALTS

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  1. ACIDS, BASES AND SALTS C. Smith

  2. ACIDS, BASES AND SALTS • 1. Acidsare defined as substances that producehydronium ions. An acid is a substance that releases hydrogen ions when it dissociates in water. HCl dissociates in water as follows: • HCl ---> H+ + Cl- • This solution also contains water. The hydrogen ions produced by an acid are attracted to water molecules. Hydronium ions are H3O+ ions. They are formed in the following reaction: • H+ + H2O ------> H3O+ • 2. Acids can be identified by certain properties. • (a) taste sour • (b) react with some metals to produce hydrogen • (c) conduct electricity. • 3. A strong acid dissociates completely forming manyhydronium ions. Weak acids do not dissociate completely, they produce fewhydronium ions.

  3. ACIDS, BASES AND SALTS • 4. A base is a substance that release hydroxideions, OH-. • 5. Bases have certain properties by which they can be identified. • (a) taste bitter • (b) feel slippery • (c) conduct electricity • (d) dissolve fats and oils • 6. Some bases produce many OH- ions in water solution and are called strong bases. Weak bases produce few hydroxide ions in water solution. • 7. Neutral solutions have an equal concentration of H+ ions and OH- ions. • 8. Common Acids and Bases are in a table on the next slide. • 9. An indicator is a compound that changes color as the concentration of H+ or OH- ions changes. • 10. Common Indicators are in a table on the next side. pH paper contains a mixture of various indicators. This paper will indicate both acids and bases

  4. ACIDS, BASES AND SALTS

  5. ACIDS, BASES AND SALTS

  6. ACIDS, BASES AND SALTS • 11. The pH scale gives a measure of the H+ ion concentration of a solution. This scale ranges from 0 to 14. 0 is the strongest acid and 14 is the strongest base. Pure water, which is neither an acid not a base (neutral), has a pH of 7. • strong weak N weak strong • acids acids bases bases • 0-3 4-6 7 8-10 11-14

  7. ACIDS, BASES AND SALTS • pH 2 = gastric acid pH 8 = raw egg • pH 3 = lemon juice pH 9 = baking soda • pH 4 = soda pH 10 = bar soap • pH 5 = black coffee pH 12 = ammonia • pH 7 = pure water pH 14 = oven cleaner

  8. ACIDS, BASES AND SALTS • 12. The scale is based upon the number of liters of a substance required to obtain one gram of pure hydrogen. • pH 7 = 10,000,000 liters of H2O (1 x 107 liters) • pH 3 = 1,000 liters of acid (1 x 103 liters) • ph 12 = 1,000,000,000,000 liters (1 x 1012 L) • Acids have low pH numbers because it takes less of them to get one gram of pure hydrogen. • Bases have high pH numbers because it takes more of them to get one gram of pure hydrogen.

  9. ACIDS, BASES AND SALTS • 13. A neutralization reaction is when an acid and base react to produce a salt and water. • acid + base ---> salt + water • HCl + NaOH---> NaCl +H2O • 14. Salts are a product of a neutralization reaction. A salt is formed from the positive ion of a base and the negative ion of an acid. • Salt properties: • (a) taste salty • (b) conduct electricity • (c) crystal structure

  10. ACIDS, BASES AND SALTS • H____ + ____OH ---> ____ ____ + HOH • acid base salt water • Al(OH)3 + HNO3 ---> • Mg(OH)2 + HBr ---> • NaOH + H2SO4 ---> • KOH + HCl --->

  11. ACIDS, BASES AND SALTS • 15. Acid rain is any rain that has a pH below 5.6 Normal rainfall ha a pH of approximately 5.6. • Some effects of acid rain include dissolving marble in buildings and statues, and making soil and water unsuitable for many life. Acid rain is caused by sulfur oxides and nitrogen oxides reacting with the atmosphere to form acids. • NO2 + H2O ---> HNO3 • SO2 + H2O ---> H2SO3 • CO2 + H2O ---> H2CO3

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