Preparation of 6.9 buffer:

Preparation of 6.9 buffer:

Weigh 0.85 gm of KH₂PO₄  and  0.88725 gm of Na₂HPO₄  and dissolve it in 250 ml of std volumetric flask and make up to the mark with distill water.

(or)

Weigh 3.4 gm of KH₂PO₄  and  3.549 gm of Na₂HPO₄  and dissolve it in 1000 ml of std volumetric flask and make up to the mark with distill water.

(or)

Weigh 1.7 gm of KH₂PO₄  and  1.7745 gm of Na₂HPO₄  and dissolve it in 500 ml of std volumetric flask and make up to the mark with distill water.