It will go backward?
Eh, not quite. The reaction with NH4+
reduces the amount of OH-
ions, ie, they are 'consumed' from the equilibrium with magnesium hydroxide solid. So essentially, you are removing OH-
ions from the expression Mg(OH)2
, this will cause the solid to dissolve more in order to produce more OH-
ions to react with NH4+
. The result of this is that the solid has become more soluble in the NH4