The molar mass of i2 is 253.80 g/mol, and the molar mass of ni3 is 394.71 g/mol. how many moles of i2 will form 3.58 g of ni3?

The balanced chemical reaction is:

N2 +3 I2 = 2NI3

We are given the amount of product formed. This will be the starting point of our calculations.

3.58 g NI3 ( 1 mol NI3 / 394.71 g NI3 ) ( 3 mol I2 / 2 mol NI3 ) = 0.014 mol I2.

Thus, 0.014 mol of I2 is needed to form the given amount of NI3.