Question

Calculate the % of boron [B] in borax Na2B4O7.10H2O.
[H = 1, B = 11, O = 16, Na = 23]

August 4, 2024

Answer

Molecular weight of borax Na₂B₄O₇.10H₂O

= 2(23) + 4(11) + 7(16) + 10[2(1)+ 16]

= 46 + 44 + 112 + 180 = 382 g

382 g of borax contains 44 g of boron

∴ 100 g of borax will contain = $44\over382$ × 100

= 11.5%

Hence, Percentage of boron is 11.5%

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