Question

If you have 1,0M NH4Cl and 0,1M NaOH, how will you mix 1L buffer solution with PH=9,0.

Can someone help ? Thanks

Answer 1

Ammonia has pKb of 4.75.

......(1)

Suppose we start with x L of 1.0 M Ammonium chloride. Since total volume is 1 L, we add (1-x) L of 0.1 M NaOH

Number of moles of ammonium chloride

Number of moles of NaOH added

moles of NaOH will combine with moles of ammonium chloride to form moles of ammonia. moles of ammonium chloride remains. Since total volume is 1 L, number of moles is equal to molarity

....(2)

But (1) = (2)

Hence, we start with 0.218 L (or 218 mL) of 1.0 M Ammonium chloride. Since total volume is 1 L, we add (or 782 mL) of 0.1 M NaOH.