Unit 9: Acids and Bases Chapter 19

Transcription

1 Unit 9: Acids and Bases Chapter 19 I. Introduction In aqueous solutions, the solvent is. Aqueous solutions contain. In the self-ionization of water, the hydrogen ion (H+) exists in solution as the ion. The relative amounts or of H+/H 3 O+ and OH determine whether a solution is,, or. [H+] = [OH ] = indicate acidic solutions indicate basic solutions indicate neutral solutions is the only substance with equal concentrations of these ions Other substances that form neutral solutions in water are classified as II. Characteristics of Acids and Bases ACIDS BASES Acids and Bases Page 1

2 III. Models of Acids and Bases A. The Arrhenius Model Acid: Base: Example Example Problem: B. The Brønsted-Lowry Model The Brønsted-Lowry Model is a more model:. Acid: Base: Example of an acid: Ionization of hydrogen fluoride in water HF(g) + H 2 O(l) H 3 O+(aq) + F (aq) Acid Base Forward Reaction Acid and Base Conjugate Base Conjugate Acid Reverse Reaction Conjugate Acid and Conjugate Base Conjugate acid-base pair: In the ionization of HF, conjugate acid-base pairs: differ by one hydrogen ion differ by one hydrogen ion Acids and Bases Page 2

3 Example of a base: Dissociation of ammonia in water H 2 O(l) + NH 3 (g) NH 4 +(aq) + OH (aq) Acid Base Forward Reaction Acid and Base Conjugate Base Conjugate Acid Reverse Reaction Conjugate Acid and Conjugate Base In the dissociation of ammonia, conjugate acid-base pairs: differ by one hydrogen ion differ by one hydrogen ion As seen in these examples, can act as both an acid and a base, making it. IV. Nomenclature Naming Acids Binary Acids Binary acids contain. To name binary acids, use the prefix, the root of the second element, the suffix, followed by the word. Hydrogen and fluorine HF Hydrogen and chlorine HCl Hydrogen and bromine HBr Hydrogen and iodine HI Exception: Hydrogen and cyanide ion HCN Contains more than two elements but is named as a binary acid Tertiary Acids or Oxyacids Oxyanions are ions that contain. Acids comprised of hydrogen and oxyanions are called. The oxyacid name uses the. Acids and Bases Page 3

4 Polyatomic Ion Suffix Tertiary Acid Suffix Hydrogen and nitrate ion HNO 3 Hydrogen and nitrite ion HNO 2 Hydrogen and sulfate ion H 2 SO 4 Hydrogen and phosphite ion H 3 PO 3 Monoprotic and Polyprotic Acids A monoprotic acid has. Examples: A polyprotic acid donates. Examples: is protic; is protic Naming Bases A base is named with the element name of the, followed by the. KOH Common name: potash lye NaOH Common name: soda lye Exception: does not contain hydroxide must memorize! Naming Practice Name the following acids. 1. HI 2. HClO 3 3. HClO 2 4. H 2 SO 3 5. H 2 S 6. H 3 PO 4 7. H 2 Se 8. HC 2 H 3 O 2 9. H 2 CrO H 2 CO 3 Acids and Bases Page 4

5 Name the following bases. 1. Mg(OH) 2 2. Ca(OH) 2 3. LiOH 4. Sr(OH) 2 5. Ni(OH) 2 6. Ba(OH) 2 7. RbOH 8. Al(OH) 3 9. LiOH 10. Cu(OH) 2 V. Strengths of Acids and Bases Acids and bases are, meaning that they. Therefore, solutions of acids and bases. Strengths of Acids Strong acids. This property makes them. Strong acids have a, and they form. Weak acids in dilute aqueous solutions. There are six strong acids; all others are considered weak. Ionization Equations Strong Acids Weak Acids Name Ionization Equation Name Ionization Equation Hydrochloric Hydrofluoric Hydrobromic Hydrocyanic Hydroiodic Acetic Perchloric Phosphoric Nitric Carbonic Sulfuric Nitrous Strengths of Bases Strong bases are those that in water. The are considered strong bases. Strong bases have a, and they produce. Weak bases in dilute aqueous solutions. Ammonia and diethylamine are weak base examples. Acids and Bases Page 5

6 Ionization Equations NaOH (s) Diethylamine C 2 H 5 NH 2 (aq) + H 2 O (l) C 2 H 5 NH 3 + (aq) + OH (aq) KOH (s) RbOH (s) Methylamine CH 3 NH 2 (aq) + H 2 O (l) CH 3 NH 3 + (aq) + OH (aq) CsOH (s) Ca(OH) 2 (s) Ammonia NH 3 (aq) + H 2 O (l) Ba(OH) 2 (s) Strength and Conductivity Solutions that contain ions are able to conduct electricity and are called. Therefore, acids and bases conduct an in solution. The strength of the current conducted is related to the. Strong acids and bases conduct electric currents than weak acids and bases. Concentration Strong: Weak: Concentration of acids and bases : : Describing acids and bases Strong: Weak: VI. ph and poh The ph of a solution is related to the. The poh of a solution is related to the. The ph scale ranges in value from. A solution with a ph value. A ph value of 0 indicates. As the ph value increases,. A ph value of 14. As the ph value decreases,. One ph unit represents. A solution with a ph of 2 has than a solution with a ph of 3. A solution with a ph of 4 has 100 times more H + than a solution with. A solution with has 1000 times less H + than a solution with a ph of 9. Acids and Bases Page 6

7 The ph and poh Scales Label the ph and poh scales from 0 to 14. Color the acidic area of the arrow red and the basic area of the arrow blue. Label the acid, base, and neutral sections of the scale appropriately. Indicate where strong acids and bases fall on the scale. Give the poh values that correspond to the following ph values. 2.0; 6.3; 4.7; 3.5; Give the ph values that correspond to the following poh values. 11.5; 6.0; 9.2; 8.5; Arrange the following combinations of ph values from most acidic to most basic. 9.7, 0.75, 6.4, 7.3, 10.9, 1.02,,,,, 8.6, 11.5, 2.02, 4.7, 6.9, 14.0,,,,, VII. Acid Base Indicators in solution depending on the ph : can identify substance as acid or base but does not indicate ph value : organic molecules that work as color dyes : : : changes to wide range of colors, which is compared to a key to determine ph : electronic device that gives ph on LCD readout : beet juice or purple cabbage juice Acids and Bases Page 7

8 VIII. Buffers Buffer: Purpose: Applications: Example: Reaction Between Acids and Bases : type of double replacement reaction in which an acid and a base react in aqueous solution to produce water and a salt ( ). Predict the products of the following reactions and balance the resulting chemical equations. 1. H 2 SO 4 + KOH 2. HNO 3 + LiOH 3. H 3 PO 4 + Ca(OH) 2 4. HCN + NaOH 5. HCl + Mg(OH) 2 A solution is made by dissolving grams of hydrogen chloride gas in enough water to form 275 ml of solution. What type of solution will form: acidic, basic, or neutral? Calculate the molarity of the solution. Write the ionization equation showing how hydrogen chloride dissolves in water. If one mole of hydrogen chloride dissolves, how many particles are produced in solution? Acids and Bases Page 8