Final answer:
To find the number of moles of I2 that will form 38.58 g of NI3, we use the molar mass of NI3 to convert the given mass to moles and then apply the stoichiometry of the reaction. We find that 0.0977 moles of NI3 would require a third of that amount on moles of I2, resulting in 0.03257 moles of I2.
Step-by-step explanation:
To calculate the number of moles of I2 that would form 38.58 g of NI3, we need to use the molar mass of NI3 and stoichiometry from the balanced chemical equation. The molar mass provided for NI3 is 394.71 g/mol.
First, we convert the mass of NI3 to moles using its molar mass:
moles of NI3 = mass of NI3 / molar mass of NI3 = 38.58 g / 394.71 g/mol
This gives us 0.0977 moles of NI3 (after rounding to four significant figures).
The balanced chemical equation for the formation of NI3 involves a 1:3 molar ratio between NI3 and I2:
3 NI -> NI3
Thus, the moles of I2 required would be one-third of the moles of NI3 produced. Therefore, we have:
moles of I2 = 0.0977 moles of NI3 / 3 = 0.03257 moles of I2 (to four significant figures)