What should be the minimum concentration ofNH_(4)Cl that must be present to prevent precipitation, when 0.01 M NH_(4)OH is added to 0.01 (M)M^(2+) solution? (K_(b) of NH_(4)OH = 1.75' 10^(-5) and K_(sp) of M(OH)_(2) = 44.1' 10^(-13))

What should be the minimum concentration ofNH_(4)Cl that must be prese

1.	What should be the minimum concentration ofNH_(4)Cl that must be present to prevent precipitation, when 0.01 M NH_(4)OH is added to 0.01 (M)M^(2+) solution? (K_(b) of NH_(4)OH = 1.75' 10^(-5) and K_(sp) of M(OH)_(2) = 44.1' 10^(-13))
Answer» `0.025 M` `0.01 M` `0.25 M` `0.083 M` Solution : `{:(NH_(4)CL, rarr, NH_(4)^(+) ,+ OH^(-)),(0.01-x,,b+x,x):}` `K_(b) = 1.75 xx 10^(-5) = ((b+x)x)/(0.01)` (`x = 2.1' 10^(-6)` from `K_(sp)` of `M(OH)_(2)`) `(b xx 2.1 xx 10^(-6))/(0.01) = 1.8 xx 10^(-5)` `rArr (1.75)/(2.1) xx (10^(-7))/(10^(-6)) = (1.75)/(10) = 0.083 M`