Question

What ratio of concentration of ammonia and ammonium chloride should be mixed to

prepare a buffer solution of pOH 5? (Kb for NH3 =1.8 x 10-4)​

Answer 1

The ratio of concentration of ammonia and ammonium chloride : 0.05

Further explanation

Given

pOH=5

Kb for NH3 =1.8 x 10-4

Required

The ratio of concentration of ammonia (NH₃) and ammonium chloride(NH₄Cl)

Solution

Solutions containing ammonia and its salt: ammonium chloride are called alkaline buffers

Can be formulated : ( for the same of the volume, mol=concentration)

`\tt \displaystyle [OH-]=Kb*(weak\:base\:mole)/(salt\:mole* valence)`

pOH=-log [OH⁻]

pOH=5⇒[OH⁻]=10⁻⁵

Valence for NH₄Cl = 1, so the concentration ratio :

`\tt 10^(-5)=1.8* 10^(-4)* ([~NH_3])/([NH_4Cl])\\\\0.05=([~NH_3])/([NH_4Cl])`