Problem: The decomposition of NI3 to form N2 and I2 releases − 290.0 kJ of energy. The reaction can be represented as2NI3(s) → N2(g) + 3I2(g), ΔHrxn = − 290.0 kJFind the change in enthaply when 18.0 g of NI3 decomposes.Express your answer to three significant figures and include the appropriate units.Enthalpy is an extensive property, and its value depends upon the amount of reactants undergoing the reaction. The enthalpy of the reaction when 5 mol of NI3 reacts will be five times higher than that when 1 mol of NI3 reacts.For example, consider a decomposition reaction of NI3:2NI3(s) → N2(g) + 3I2(g), ΔHrxn = − 290.0 kJWhen 2 mol of NI3 decomposes, the enthalpy of the reaction is − 290.0 kJ. If 5 mol of NI3 decomposes, the enthalpy of the reaction will be5/2 × − 290.0 = − 725.0 kJ.

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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 18.0 g of NIdecomposes.

Express your answer to three significant figures and include the appropriate units.


Enthalpy is an extensive property, and its value depends upon the amount of reactants undergoing the reaction. The enthalpy of the reaction when 5 mol of NI3 reacts will be five times higher than that when 1 mol of NIreacts.

For example, consider a decomposition reaction of NI3:

2NI3(s) → N2(g) + 3I2(g), ΔHrxn = − 290.0 kJ

When 2 mol of NIdecomposes, the enthalpy of the reaction is − 290.0 kJ. If 5 mol of NI3 decomposes, the enthalpy of the reaction will be
5/2 × − 290.0 = − 725.0 kJ.

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