Question

The chemical equation below shows the decomposition of nitrogen triiodide (NI3) into nitrogen (N2) and iodine (I2). 2NI3 mc030-1.jpg N2 + 3I2 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?

A) 0.00907
B) 0.00940
C) 0.0136
D) 0.0212

Answer 1

The moles of I2 that will form 3.85 g of NI3 is 0.0136 moles ( answer c)

calculation

2 NI3 → N2 + 3 I2

Step 1: calculate the moles of NI3 that decomposes

moles= mass/molar mass

=3.58 g/ 394.71 g/mol = 0.00907 moles

Step 2 : use the mole ratio of NI3 to I 2 which is 2:3 to calculate the moles of I2

= 0.00907 x3/2 =0.0136 moles ( answer C)

Answer 2

The balanced chemical reaction would be:

2NI3 = N2 + 3I2

We use the reaction above and the molar masses of the substances involved. We start with the initial amount of NI3 reactant.

3.58 g NI3 (1 mol NI3 / 394.71 g NI3) (3 mol I2 / 2 mol NI3) = 0.0136 mol I2

Therefore, option C is the answer.