Question

IIIIIIIIIIIIIIIIIIIIIIIIIIIIII 27) Determine the Kb for CN at 25°C. The K, for HCN is 4.9.10-10. A) 1.4. 10-5 B) 49.10-14 C) 20.10-5 D) 23.10-9 E) 3.7.10-7 28) 28) Calculate the solubility (in g/L) of calcium fluoride in water at 25°C if the Ksp for Ca F2 is 1.5 10-10 A) 9.6 10-4 g/L B) 3.3. 10-2 g/L. C) 4.1 . 10-2 g/L. D) 2.6 x 10-2 g/L 29) 29) The equilibrium constant is given for two of the reactions below. Determine the value of the missin equilibrium constant Alg) + B/s) - AB(s) AB(s) + A(g) - A2B(g) 2 A(s) +B(g) - A2B(g) Kc =0.24 Ke 3.8 Ke-? A) 3.6 B) 0.91 C) 16 D) 0.63 E) 4.0 30) Which of the following represents the equation for a second-order half-life? A)+1/2" KALO B) t1/2- TA. C) 112- D) t12-12%. E) t12-0693

Answer 1

27. Ka of HCN   = 4.9*10^-10

Kb   = Kw/Ka

        = 1*10^-14/(4.9*10^-10)

        = 2.0*10^-5

C. 2.05*10^-5

28. CaF2(s) ------------> Ca^2+ (aq) + 2F^- (aq)

                                          s                   2s

Ksp   = [Ca^2+][F^-]^2

1.5*10^-10   = s*(2s)^2

1.5*10^-10   = 4s^3

s   = 0.0003345

solubility of CaF2   = 3.345*10^-4mole/L

molar mass of CaF2   = 78.07g/mole

solubility of CaF2   = 3.345*10^-4mole/L * 78.07g/mole

                               = 2.6*10^-2g/L

D. 2.6*10^-2g/L

29.

A(g) + B(g) ------------> AB(g)     K1 = 0.24

K1   = [AB]/[A][B]

AB(g) +A(g) -------------> A2B(g)    K2 = 3.8

K2   = [A2B]/[AB][A]

K1*K2   = [AB]/[A][B] *[A2B]/[AB][A]

             = [A2B]/[A]^2[B]

0.24*3.8   = [A2B]/[A]^2[B]

0.912   = [A2B]/[A]^2[B]

2A(g) + B(g) --------> A2B(g)     Kc   = 0.91

B. 0.91

30.

second order kinetic t1/2   = 1/K[A]0

A. t1/2   = 1/K[A]0