Answer:
Hydroxy(oxo)bismuthine oxide
First convert to moles:
0.5113 g / 17 g/mol = 0.0301 mol
Now create a ratio based on the reaction provided to solve for the unknown:
4 NH3 / -905.4 kJ = 0.0301 mol NH3 / x kJ
x = -6.808 kJ
7.30 x 10^-7 km. the others have 4 significant figures.
Oxygen: 16.00 g/mol
Hydrogen: 1.01 g/mol
The mass would be 17.01 g/mol
