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Reacting boron with hydrogen?
By reacting boron with hydrogen, a certain borohydride is produced. The compound,
BxHy, will react with water to produce boric acid (H3BO3) and hydrogen gas. If you
take 2.7755 g of this borohydride and react it with water you will produce 12.4057 g
of boric acid and 1.2134 g of hydrogen gas. What is the empirical formula for this
compound? If the molecular weight of this compound is between 25 and 30 g, what
are the actual values of X and Y?
1 Answer
- BobbyLv 79 years agoFavorite Answer
Molar mass of B is 10.81g / mol
Molar mass of H3BO3 is 61.83 g / mol
moles of B in 12.4057 g of boric acid = 12.4057 x 10.81 / 61.83 = 2.169 g and 0.201 moles of B
mass of H in the borohydride = 2.7755 - 2.169 = 0.6065 H
moles of H = 0.6065 / 1.0079 = 0.6017 moles
molar ratio of B :H = .201 : .6017 or 1 :3
the empirical formula is BH3 which has a formula mass of 10.81+3 g = 13.81
the molar mass is approximately 27 so there are 2 empirical units in a mole of the borohydride
which has mass of 27.62g
molecular formula is 2 x the empirical formula or B2H6 ..
