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Acids and Bases

Acids and Bases. Mrs. Brostrom Integrated Science. Acids. An acid is any compound that increases the number of hydronium ions (H 3 O + ) when dissolved in water The hydronium ion forms when a H ion (H + ) separates from the acid and bonds with a water molecule (H 2 O )

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Acids and Bases

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  1. Acids and Bases Mrs. Brostrom Integrated Science

  2. Acids • An acid is any compound that increases the number of hydronium ions (H3O+) when dissolved in water • The hydronium ion forms when a H ion (H+) separates from the acid and bonds with a water molecule (H2O) H3O+→ H+ + H2O

  3. Properties of Acids • A sour flavor • Lemons, limes, vinegar • However, taste should never be used to identify acids • Some can be corrosive and poisonous

  4. Change color in indicators • A substance that changes color in the presence of an acid or base is an indicator • Litmus is a common indicator used to detect the strength of acids • When an acid is added to blue litmus paper, the color changes to red • React with metals to produce hydrogen gas Ex.) Hydrochloric acid reacts with zinc to produce hydrogen gas 2HCl + Zn → H2 + ZnCl2

  5. Conduct electric current • When acids dissolve in water, they break apart and form ions • Ex.) Car battery contains sulfuric acid

  6. Uses of Acids • Used in industry and homes • Sulfuric acid is most widely used industrial chemical; paper paint detergents, and fertilizers • Nitric acid; fertilizers, rubber, and plastics • Hydrochloric acid is used to make metals from their ores (by separating them), swimming pools, stomach • Hydrofluoric acid is used to etch glass • Citric acid and ascorbic acid are found in orange juice • Carbonic acid and phosphorous acid are found in soda

  7. Bases • A base is any compound that increases the number of hydroxide ions (OH-) when dissolved in water • Ex.) Sodium hydroxide breaks apart to form sodium ions and hydroxide ions NaOH → Na+ + OH-

  8. Properties of Bases • Bitter taste • Taste should never be used to identify a base, like acids they are corrosive • Slippery feel • Ex.) Soap

  9. Bases change colors in indicators • Like acids, litmus is a common indicator used to detect the strength of bases • Bases change the color of red litmus paper to blue • Bases conduct electric current • Bases increase the number of hydroxide ions (OH-) which has a negative charge

  10. Uses of Bases • Sodium hydroxide, used to make soap, paper, oven cleaners, drain cleaners • Calcium hydroxide, used to make cement and plaster • Ammonia, found in many household cleaners and used to make fertilizer • Magnesium hydroxide and aluminum hydroxide, used in antacids

  11. Solutions of Acids and Bases Mrs. Brostrom Integrated Science

  12. Strengths of Acids • Strength of acids and bases are not the same as concentration • As an acid dissolves in water, the molecules break apart producing hydrogen ions (H+). If all the molecules break apart, the acid is called strong acid. • Strong acids include sulfuric acid, nitric acid, and hydrochloric acid • If only a few molecules break apart, it is aweak acid. • Weak acids include acetic acid, citric acid, and carbonic acid

  13. Strengths of Bases • When all of the molecules of a base break apart in water to produce hydroxide ions (OH-)the base is a strong base • Sodium hydroxide, calcium hydroxide, and potassium hydroxide • When only a few molecules break apart it is a weak base • Ex.) Ammonium hydroxide and aluminum hydroxide

  14. Neutralization • The reactions between acids and bases is a neutralization reaction • The hydrogen ions (H+) that are present in an acid and the hydroxide ions (OH-) that are present in a base react to form water H+ + OH- → H2O • The other ions in the acids and base dissolve in the water and if it evaporates, bond together to produce salt

  15. For Example…

  16. The pH Scale • The pH of a solution is a measure of the hydronium ion concentration in a solution • pH of 7 is neutral (neither acid or base); pure water • Basic solutions have a pH greater than 7 • Acidic solutions have a pH less than 7

  17. Measuring pH • pH can be measured using • pH (litmus) paper • pH meter • Living things depend on having a steady pH - lettuce needs basic soil; between 8 and 9 • Most rain has a pH between 5.5 and 6

  18. Salts • When an acid neutralizes a base, water and salt is produced • A salt is an ionic compound formed from the positive ion of a base and the negative ion of an acid • NaCl, used to season food • Sodium nitrate, used to preserve food HCl + NaOH → H2O + NaCl

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