Question

12. The [OH7m a 0.75 M pyridine (CsHsN?-17-10-9) solution is: a. 1.3109 M 0.75 M enone of these 3.6× 10-5 4.8 × 10-5 Al 1.3. Consider the reaction HNOzla) H:0DH'(ap)+NOz (ag) Which species is a conjugate base? a HNOz(ag) b. H2O? c Ho (ag) d. NO2 (ag) e. Two of these 14. Which of the following is the equilibrium constant expression for the dissociation of the weak acid HOCi [HOCI] Hoa e. None of these 15. The highest plH for an effective buffer occurs when the base is how many times as concentrated as the aci a. b. 5 c. 10 d 20 e. 15 16. The concentration of OH in a saturated solution of Mg(OH)2 ?S 357 x 104 M.The Ksp of Mg(OH)2 a. 6.4x 10-8 b. 4.5 x 10-11 . 1.3 x10-7 d. 3.6x 10-4 e. 2.3x 10-11 ion for findine the melar solubility (s) of Sn(OH)2 is

Answer 1

HNO_2(ag + H_3(l) doubleheadarrow H_3O^+ + NO_2^- Therefore answer is (d) NO_2^- (ar) (14) HOcl doubleheadarrow H^+ + ocl^- k = [H^+][ocl^-]/[HOcl] Therefore The answer is (a) [H^+][ocl^-]/[HOcl] (15) PH of a buffer solution is given by Henderson - Hasselbach equation PH = KK_q + log [base]/acid] For an effective buffer [base] should be equal to [acid]. And for maximum output of [base] should not be more then 10 fold of [acid] i.e PH = PK_a plusminus 1 rightarrow effictive buffer PH = PK_a + log 10[acid]/[acid] = PK_a + log10 = PK_a + 1 So, highest PH is for (c) 10 (16) mg (OH_2) doubleheadarrow mg^2+ + 2OH^- Let s be solubility K_sp = [mg^2+][OH^-]^2 Given, [OH^-] = 3.57 times 10^-4 M Therefore [mg^2+] = 3.57 times^-4/2 M So, K+sp = (3.57 times 10^-4/2)(3.57 times 10^-4)^2 or, K_sp = 2.27 times 10^-11 = 2.3 times 10^11 So, the answer is 2.3 times 10^11