For the following, consider Mg(OH) 2 (s) dissolved in 1.00 M NH 4 Cl(aq). Mg(OH)
ID: 879731 • Letter: F
Question
For the following, consider Mg(OH)2(s) dissolved in 1.00 M NH4Cl(aq).
Mg(OH)2(s) <----> Mg2+(aq) + 2 OH-(aq) Ksp = 1.8x10-11
NH3(aq) + H2O(l) <------> NH4+(aq) + OH-(aq) Ksp = 1.8x10-5
A) What is the numerical value of the equilibrium constant for the neutralization that occurs when Mg(OH)2 is added to the solution?
B) Find the equilibrium concentrations for the equilibrium of part (A) in terms of x, the change in initial concentrations. Plug these values into the equilibrium constant expression of part (A), and rearrange the terms to make a cubic expression in the form of ax3 + bx2 + cx + d = 0.
C) The cubic equation of part (B) has 2 imaginary roots and one real root. Given the real root is x = 0.178, find the solubility of Mg(OH)2 in this ammonium chloride solution in g/L.
Explanation / Answer
1) the numerical value of the equilibrium constant for the neutralization that occurs when Mg(OH)2 is added to the solution Ka=5.6*10-10.
Mg(OH)2 (s) + 2 NH4+ (aq) <---> Mg2+ (aq) + 2 NH3 (aq) + 2H2O