Finding Ksp from given concentration

Question

Determine the Ksp for Ba(NO₃)₂. The concentration of Ba²⁺ in a saturated solution of Ba(NO₃)₂ is 0.105 M. What is the concentration of nitrate ions?

Answer 1

Ba(NO3)2 <--------> Ba^2+ + 2NO3^1-

using the molar ratio of Ba^2+ to NO3^1-

Ba^2+ 0.105 mol x 2NO3^1-mol/1 mol Ba^2+ = 0.21M NO3^1-

Ksp = [Ba^2+][NO3^1-]^2

Ksp = (0.105)(0.21)^2

Ksp = 4.63 x 10^-3