Question

The decomposition of N I 3 to form N 2 and I 2 releases − 290.0 kJ of energy. The reaction can be represented as 2N I 3 (s)→ N 2 (g)+3 I 2 (g), ΔH rxn =−290.0 kJ Find the change in enthaply when 10.0 g of N I 3 decomposes. Express your answer to three significant figures and include the appropriate units.

Answer 1

Answer:

The change in enthaply when 10.0 g of nitrogen triiodide decomposes is -3.67 kJ.

Explanation:

$2NI_3 (s)\rightarrow N_2 (g)+3 I_2 (g), \Delta H_{rxn} =-290.0 kJ$

Enthalpy of the reaction when 2 moles of nitrogen triiodide decomposed =$\Delta H_{rxn}$

$\Delta H_{rxn} = -290.0 kJ$

Enthalpy of the reaction when 1 moles of nitrogen triiodide decomposed :

$\Delta H=\frac{\Delta H_{rxn}}{2}=\frac{-290.0 kJ}{2} =-145.0 kJ$

Mass of nitrogen triiodide decomposed = 10.0 g

Moles of nitrogen triiodide = $\frac{10.0 g}{395 g/mol}=0.02532 mol$

Change in enthaply when 0.02532 moles of nitrogen triiodide decomposed:

$\Delta H\times 0.02532=-145 kJ\times 0.02532=-3.67 kJ$