What is percent by mass of water in the hydrate sodium bicarbonate octahydrate?

50%

Explanation:

Formula of this hydrate is given as:

      Sodium bicarbonate octahydrate   =   NaHCO₃ . 8H₂O;

To find the percent by mass of water;

Sometimes it is good to know the percent by mass of elements or groups present in a compound. Find the formula mass by summing the atomic masses. Determine the percentage composition of an atom or group by expressing as a percentage of the formula mass.

  Formula mass of  NaHCO₃ . 8H₂O;

                               = 23 + 1 + 12 + 3(16 ) + 8[2(1) + 16]

                                = 228g/mol

 for the 8H₂0 = 8(18) = 144

%H₂O  =   = 50%

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