The equivalent mass of Ba(OH)2.8H2O as a base (H = 1, O = 16, Ba = 137) is:

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The equivalent mass of $Ba (OH) X_{2} \cdot 8 H X_{2} O$ as a base (H = 1, O = 16, Ba = 137) is:

Molar mass = 137 + 34 + 8(18) = 315 g/mol. The base supplies 2

OH X^{-}

per formula unit, so n = 2 (water of crystallisation does not change n). Equivalent mass = 315/2 = 157.5 g/eq.