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Acids & Bases Chapter 16 Students Notes

Acids & Bases Chapter 16 Students Notes. Acids. Characteristically have at least one hydrogen atom Examples: HCl, H 2 SO 4 , HNO 3. Properties of Acids. tastes sour corrosive & can damage skin or tissue feel like water, except on broken skin

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Acids & Bases Chapter 16 Students Notes

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  1. Acids & BasesChapter 16Students Notes

  2. Acids • Characteristically have at least one hydrogen atom • Examples: • HCl, H2SO4, HNO3

  3. Properties of Acids • tastes sour • corrosive & can damage skin or tissue • feel like water, except on broken skin • react with an indicator (such as litmus or pH paper) to produce a predictable color change • turns blue litmus paper RED • react with metals to produce hydrogen gas • dissolves in water to form an electrolyte solution

  4. Common Acids • Foods contain Acids • Citric acid – in citrus fruits like oranges • Lactic acid – in dairy products like yogurt and buttermilk • Acetic acid (vinegar) – used to pickle foods • The stomach uses hydrochloric acid • Industrial Acids • Sulfuric acid • Used in car batteries and the manufacturing of fertilizers. • Phosphoric acid • Used to manufacture detergents, fertilizers, and soft drinks. • Nitric acid • Used to make fertilizers and explosives • Hydrochloric acid • Used to clean steel

  5. Bases • Characteristically forms hydroxide (OH-) ions in solution • Examples: • KOH, NH4OH, Ca(OH)2

  6. Properties of Bases • tastes bitter • many are crystalline solids in pure undissolved state • strong bases can be corrosive & can damage skin or tissue • feel slippery in solution • react with an indicator (such as litmus or pH paper) to produce a predictable color change • turns red litmus paper BLUE • dissolves in water to form an electrolyte solution

  7. Common Bases • Bases have different uses: • Cleaning products • Medications • Fabrics • Detergents

  8. Types of Acids & Bases • Arrhenius Acids • substances that contain hydrogen and ionizes to produce hydrogen ions in an aqueous solution • HCl(g) H+(aq) + Cl-(aq) • Arrhenius Bases • a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in an aqueous solution. • NaOH(s) Na+(aq) + OH-(aq) • Bronsted-Lowry Acid • substance that donates a hydrogen ion • HF + H2O  H3O+ + F- • Bronsted-Lowry Base • substance that accepts a hydrogen ion • NH3 + H2O  NH4+ + OH- • Amphoteric • a substance that can act as both an acid and a base

  9. Strength of Acids & Bases • The strength of an acid or base depends on how COMPLETELY a compound separates into its ions when dissolved in water • STRONG ACID • Almost ionized completely in solution • WEAK ACID • Partly ionizes in solution • STRONG BASE • Dissociates completely in solution • WEAK BASE • Does not ionize completely in solution • Strong acids and bases conduct MORE electricity than weak ones

  10. Acid & Base Equations • Equations for strong acids and bases use a single arrow, indicating ions are formed. HCl + H2O  H3O+ + Cl- NaOH  Na+ + OH- • Equations for weak acids and bases use double arrows, pointing in opposite directions, indicating an incomplete reaction. Ca(OH)2  Ca2+ + 2OH- HC2H3O2 + H2O  H3O+ + C2H3O2-

  11. Concentrations of Acids & Bases • “Dilute” and “concentrated” are terms used to describe the amount of acid or base dissolved. • Dilute • few molecules of an acid or base dissolved in a volume of solution. • Concentrated • many molecules of an acid or base dissolved in a volume of solution.

  12. pH • pH-a scale used to classify acids and bases • the pH scale ranges from 0-14 • acids have a pH below 7 • bases have a pH above 7 • neutral substances have a pH of 7

  13. Ions in solution • Acidic solutions have more hydrogen ions than hydroxide ions. • Basic solutions have more hydroxide ions than hydrogen ions. • Neutral solutions have an equal number of hydrogen ions and hydroxide ions.

  14. Calculating pH • pH is the negative logarithm of the hydrogen ion concentration pH = -log [H+] • Calculate the pH of a solution having a hydrogen ion concentration of 1.0x10-2 M. pH = -log [H+] pH = -log[1.0 x 10-2] pH = 2

  15. Calculating pOH • pOH • the negative logarithm of the hydroxide ion concentration pOH = -log[OH-] • Calculate the pOH of a solution with a hydroxide ion concentration of 1.0 x 10-6M. pOH = -log[OH-] pOH = -log[1.0 x 10-6] pOH = 6

  16. Relationships between pH and pOH pH + pOH = 14 pH = 14 – pOH pOH = 14 – pH

  17. PRACTICE CALCULATING pH Calculate the pH and pOH of the a solution with a hydroxide ion concentration of 3.20 x 10-9M. G: hydroxide ion concentration of 3.2 x 10-9M. U: pH and pOH E: pOH = -log[OH] and pH = 14 – pOH S: pOH = -log[3.20 x 10-9] pOH = 8.49 pH = 14 – pOH pH = 14 – 8.49 pH = 5.51

  18. Neutralization • Neutralization • chemical reaction between an acid and a base in an aqueous solution producing a salt and water • a double replacement reaction. • Salt • ionic compound made up of a cation from a base and an anion from an acid. Mg(OH)2 + HCl  MgCl2 + 2H2O

  19. Titration • Titration • used to determine the concentration of an acidic or basic solution • A solution of known concentration is the standard solution. • An acid/base indicator is added to the unknown solution. • A color change that persists is the end point.

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