[A] + [B] ⇌ [C] + [D]
MnS ⇌ Mg + S
Ksp = [C][D]
Ksp = (Mn)(S)
2.3*10^-13 = (x)(x)
2.3*10^-13 = x^2
x = 4.8*10^-7
Concentration of sulfide is x.
Today, my son asked "Can I have a book, Mark?" and I burst into tears. 11 years old and he still doesn't know my name is Brian.