Borax in water gives the following:
`B_4O_7^(2-)+7H_2Oto4H_2BO_3+2overset(ɵ)(O)H`
How many grams of borax `(Na_2B_4O_7.10H_2O)` are required to
(a). Prepare 50 " mL of " 0.2 M solutionl.
`(Mw` of borax`=382`)

Explanation

`B_4O_7^(2-)+7H_2Oto4H_3BO_3+2overset(o+)(O)H`
So, borax is a diacidic bese.
(a). Millimoles `=(Weight)/(Mw)xx1000`
`implies50xx0.2=(weight)/(382)xx1000impliesweight=3.82g`
(b). `mEq=(weight)/(E)xx1000implies2xx0.2xx25`
`=(weight)/((383)/(2))xx1000`
Weight`=1.91g`