Answer:
37.09 g of B₅H₉ is required to form 148 g of  borate salt( Na₂B₄O₇  )
Explanation:
Given the data in the question;
B₅H₉ → H₃BO₃ → Na₂B₄O₇
find the mass (in grams) of B5H9 required to form 148 g of the borate salt by this reaction sequence.
S Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â M.W
B₅H₉              63
H₃BO₃            62
Na₂B₄O₇          201
So, moles of Na₂B₄O₇  = 148 / 201 = 0.736
Since Boron will be conserved,
Moles of Boron atoms in Na₂B₄O₇  will be;
⇒ 4 × 0.736 = 2.944
Now, Moles of Boron in Naâ‚‚Bâ‚„O₇ = Moles of Boron in H₃BO₃ = Moles of Boron in Bâ‚…H₉ Â
Hence,
Moles of Boron in B₅H₉ = 2.944
Moles of B₅H₉ = 2.944 / 5 = 0.5888
Mass of B₅H₉ = 0.5888 × 63 = 37.09 g
Therefore, 37.09 g of B₅H₉ is required to form 148 g of  borate salt( Na₂B₄O₇  )