Chemistry Lecture 6 Volodimir Vreshch Ivano-Frankivsk 1

Chemistry Lecture #6 Volodimir Vreshch Ivano-Frankivsk

1 Plane Introduction Electrolytic dissociation Dissociation rate Dissociation of acids bases and salts Exchange reactions , salt hydrolysis Conclusions

2 Electrolytic dissociation An electrolyte is a compound that ionizes when dissolved in suitable ionizing solvents such as water. _ Катод Na+ Cl– +

3 Electrolytic dissociation Na+ Cl– Cl– Na+

4 Electrolytic dissociation Strong Bases Salts H 2 SO 4, HNO 3, HCl, HBr, HI, HMn. O 4, HCl. O 4 HNO 2, HF, H 2 SO 3, СН 3 СООН, H 2 S, H 3 PO 4, HPO 3 НСООН, НСN, H 2 CO 3, H 3 BO 3, H 2 Si. O 3, HCl. O Na. OH, KOH, Li. OH, Cs. OH, Ca(OH)2, Ba(OH)2, Sr(OH)2, Tl. OH NН 4 ОН, Fe(OH)3, Cr(OH)3, Cu(OH)2, Al(OH)3, Bi(OH)3, Be(OH)2 Almost all Acid Average Week Нg 2 Сl 2, Fe(SCN)3, Pb(СН 3 СОО)2

Electrolytic dissociation Kra. Anb = a. Ktb+ + b. Ana. Due to mass action law : 5

6 Electrolytic dissociation 1 -st level : H 3 PO 4 = H+ + H 2 PO 4 - Kd 1 = 7. 6· 10 -3 2 -st level : H 2 PO 4 - = H+ + HPO 42 - Kd 2 = 5. 9· 10 -8 3 -st level : HPO 42 - = H+ + PO 43 - Kd 3 = 3. 5· 10 -13

Electrolytic dissociation 7

p. H : definition р. Н = –lg[H+], so [H+] = 10– р. Н, р. OН = –lg[OH–], so[OH–] = 10– р. OН, p. H + p. OH = 14 7

8 p. H : indicator Different colors of p. H indicator depends on acidity of the solution р. Н 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 acidic p. H<7 neutral p. H=7 basic p. H>7

Electrolytic dissociation : example KNO 3 + НОН HOH ОH– + H+ КОН + НСl ↔ КСl + Н 2 О ОН– + Н+ ↔ Н 2 О KOН + НNО 3 р. H=7 9