What concentration of NH4NO3 is required to make is required to make [OH-] is required to make [OH-]=1.0*10^-5 in a 0.200-M solution of NH3

Question

What concentration of NH4NO3 is required to make is required to make [OH-] is required to make [OH-]=1.0*10^-5 in a 0.200-M solution of NH3

Answer 1

NH₃ + H₂O --> NH₄⁺ + OH^-

^{pOH = pK}_b ^{+ log [acid]/[base]}

[OH^-] = 1.0 × 10^-5 M, pOH = 5

K_b = 1.8 × 10^-5, pK_b = 4.74

[ acid ] = [ NH₄⁺ ], [ base ] = [ NH₃ ] = 0.200M

5 = 4.74 + log [NH₄⁺]/(0.2)

[ NH₄⁺ ] = 0.364M

NH₄NO₃ --> NH₄⁺ + NO₃^-

[ NH₄NO₃ ] = [ NH₄⁺ ] = 0.364M concentration required