20 ml of 0.1 M NH, solution is titrated with 0.025M HCI solution. What is the pH of the reaction mixture at equivalence point at `25^(@)`C ? `(K_(b) "of " NH_(3) "is " 2 xx 10^(-6))`.

Answer

5

Explanation

` N_aV_a =N_b V_b `
` 0.1 xx 20 = 0.025 xx V_b` ` 0.1 xx 20 = 0.025 xx V_b rArr V_b = 80 ml`
no . Of m moles of formed `NH_4Cl =2`
`M _(NH_4Cl ) = ( 2xx 10 ^(_3))/( 100 ) xx 1000 = 0.02M`
` pH =7 - ((6- log 2)/(2)) -(1)/(2) ( Log 2- 2 ) rArr pH= 5`