Question

the compound diborane can be used as a rocket propellant. what is the percent composition of boron in diborane (b₂h₆)?
a. 22%
b. 25%
c. 39%
d. 75%
e. 78%

Explanation:

Step1: Find atomic masses

Atomic mass of B = 10.81 g/mol, H = 1.01 g/mol

Step2: Calculate molar mass of \(B_2H_6\)

\(M = 2\times10.81+6\times1.01=21.62 + 6.06=27.68\) g/mol

Step3: Calculate mass of B in \(B_2H_6\)

Mass of B in \(B_2H_6\) is \(2\times10.81 = 21.62\) g/mol

Step4: Calculate percent composition of B

Percent composition of B=\(\frac{21.62}{27.68}\times100\%\approx78\%\)

Answer:

E. 78%