Question

The decomposition of NI3 to form N2 and I2 releases −290.0 kJ of energy. The reaction can be represented as 2NI3(s)→N2(g)+3I2(g), ΔHrxn=−290.0 kJ Find the change in enthaply when 20.0 g of NI3 decomposes.

Answer 1

Answer:

-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.

Explanation:

Mass of nitrogen triiodide = 20.0 g

Moles of nitrogen triiodide = $\frac{20.0 g}{395 g/mol}=0.05063 mol$

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

According to reaction, 2 moles of nitrogen triiodide gives 290.0 kilo Joules of heat on decomposition ,then 0.05063 moles of nitrogen triiodide will give :

$\frac{-290.0 kJ}{2}\times 0.05063=-7.34 kJ$

-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.