复旦大学：《普通化学 General Chemistry》课程教学资源（课堂讲义）Chap 6 - Solution & Precipitate

PART 6A- Solution Reference: Chapter 4 in textbook PART 6B-Precipitate Reference: Chapter 16.5-16.8 in the textbook

PART 6A PART 6A – Solution Solution Reference: Chapter 4 in textbook PART 6B – Precipitate Reference: Chapter 16 5 Reference: Chapter 16.5—16 8 in the 16.8 in the textbook 1

Solution Solute, Solvent, and Solution ●●●●●● ●●●●●● 十 ●0●o Sugar ●o●oa 00●0o● Water Solution Saturated solution and Solubility Saturated solution: Dynamic equilibrium Solubility: the maximum mass of a solute that can be dissolved in a solvent (100 g), and is temperature dependent 2

Solution z Solute, Solvent, and Solution z Saturated solution and Solubility „ Saturated solution: Dynamic equilibrium „ Solubility lubility:the maximum mass of a solute that can be dissolved in a solvent (100 g), and is temperature dependent. 2

Solubility Preparation, separation from solution Q: Which of these solutes' solubility are the most sensitive to temperature? Na2s04 Solubility VS Temperature for a variety of salts Ba(o3)2 H Ce2(S04)3 9H20 Na2HAsO4 0000000p0 Temperature 3

Solubility z Preparation, separation from solution „ Q: which of these solutes’ solubility are the most sensitive to temperature? sensitive to temperature? 3

Solubility and molarity Recapture: What is solubility? What is molarity? Q: At 25oC, the solubility of sodium chloride (Naci)in 100 g water is 36.0 g. When we put 30 g Nacl into 75 g water, what is molarity of this NacI solution?(Assuming the density of water and Nacl solution are both 1.0 g/mL)

Solubility and Molarity z Recapt re What is sol bilit ? What is Recapture: What is solubility? What is molarity? „ Q: At 25 oC, the solubility of sodium chloride (NaCl) in 100 g water is 36 0 g When we put 30 g (NaCl) in 100 g water is 36.0 g. When we put 30 g NaCl into 75 g water, what is molarity of this NaCl solution? (Assuming the density of water and NaCl solution are both 1 0 g/ml ) solution are both 1.0 g/ml.) 4

Electrolyte Electrolyte Compounds that conduct electricity when dissolved or melted Strong electrolyt Most of the solute dissociates into ion forms e.g. strong acids, strong bases, salts Weak electrolyte Most of the solute remains as molecule forms 5

Electrolyte z Elec o y e trolyte: „ Compounds that conduct electricity when dissolved or melted. z Strong electrolyte: Strong electrolyte: „ Most of the solute dissociates into ion forms. „ e.g. strong acids, strong bases, salts. z Weak electrolyte: Weak electrolyte: „ Most of the solute remains as molecule forms. 5

acid Base, and salt Salt Compound of metallic (or polyatomic) cations and nonmetallic anions Salts can be either soluble or insoluble in water ■eq.NaC|→Na++C|,NHNO2→NHA++NO2,AgC → insoluble,caCO3→ insoluble Are insoluble salts electrolytes 6

Acid, Base, and Sal t z Salt „ Compound of metallic (or polyatomic) cations and nonmetallic anions. „ Salts can be either soluble or insoluble in water. Salts can be either soluble or insoluble in water. „ e.g. NaCl Æ Na + + Cl-, NH 4NO 3 Æ NH 4 + + NO 3 -, AgCl Æ insoluble, CaCO 3 Æ insoluble „ Q: Are insoluble salts electrolytes? Are insoluble salts electrolytes? 6

Calculation in Solution Strong electrolyte Fully dissociated -all solute molecules are dissociated into cations and anions Q1: When dissolved 10 g nacl in 30 g water what is the molarity of each solute species? Q2: In the solution above add 10 g agno 3, what is the molarity of each solute species?(Ag* will react with CI- to form insoluble AgCl solid. 7

Calculation in Solution z Strong electrolyte Strong electrolyte „ Fully dissociated – all solute molecules are dissociated into cations and anions. „ Q1: When dissolved 10 g NaCl in 30 g water what When dissolved 10 g NaCl in 30 g water, what is the molarity of each solute species? „ Q2: In the solution above, add 10 g AgNO 3, what is the molarity of each solute species? (Ag is the molarity of each solute species? (Ag + will react will react with Cl- to form insoluble AgCl solid.) 7

Calculation in Solution Weak electrolyte Partially dissociated -only a faction(a)of solute molecules are dissociated into cations and anions When dissolved 10 g ethanoic(acetic)acid (CH3COOH, a weak mono-protonic acid)in 30 g water, if the dissociation factor is 0.1, what is the molarity of each solute species? H-C-C-O-H 8

Calculation in Solution z Weak electrolyte Weak electrolyte „ Partially dissociated – only a faction ( α) of solute molecules are dissociated into cations and anions. „ Q: When dissolved 10 g ethanoic (acetic) acid When dissolved 10 g ethanoic (acetic) acid (CH 3COOH, a weak mono-protonic acid) in 30 g water, if the dissociation factor is 0.1, what is the molarity of each solute species? each solute species? 8

Reaction between ions in Solution Rule for predicting reactions between electrolytes When solutions of electrolytes are mixed, a reaction will take place if one or both of the possible products is either insoluble, gas, or a weak or non-electrolyte First write all reactants in ion or molecule forms then crosslink cations and anions to compare 9

Reaction between Ions in Solution z R le for predicting reactions bet een R ule for predicting reactions bet ween electrolytes: „ – When solutions of electrolytes are mixed, a reaction will take place if one or both of the possible products will take place if one or both of the possible products is either insoluble, gas, or a weak or non-electrolyte. „ First, write all reactants in ion or molecule forms; then crosslink cations and anions to compare crosslink cations and anions to compare. 9

Reaction between ions in solution Water solubility of Generally Soluble Anion Exceptions common InorganIc Nitrates N compounds Acetates None A general description ulfates Silver, Lead, Calcium Chlorides Silver, Lead in Pg. 117, Table 4. 4 Not Generally Soluble Some simple rules Anion Except Hydroxides Sodium, Potassium, Ammonium, Calcium are shown on right Oxides Sodium Potassium, Ammonium Sulfide Sodium, Potassium, Ammonium Carbonates Sodium, Potassium, Ammonium 10

Reaction between Ions in Solution z Water sol bilit of Water sol ubility of common inorganic compounds „ A general description A general description in Pg. 117, Table 4.4. „ Some simple rules are shown on right are shown on right. 10