Question

if heat of formation of no2 is x 1/2 and 2 o2 gives no the heat of reaction n2 o2 gives to no is why the

Answer 1

The heat of formation refers to the energy change when a compound is made from its elements. To calculate the heat of reaction for the formation of NO₂ from N₂ and O₂, steps involve the initial formation of NO and its subsequent oxidation. Hess's law and the enthalpy of formation values are used in these calculations.

Step-by-step explanation:

When we talk about the heat of formation, it refers to the heat change that occurs when one mole of a compound is formed from its elements in their standard states. The reaction of nitrogen (N₂) and oxygen (O₂) to form nitrogen dioxide (NO₂) involves several steps and is relevant to the formation of urban smog.

From the provided reactions, we can deduce the steps:

1. N₂(g) + O₂(g) → 2 NO(g) (Initial formation of NO)
2. 2 NO(g) + O₂(g) → 2 NO₂(g) (Oxidation of NO to NO₂)

By applying Hess's law and knowing the enthalpy of formation (ΔHf) for NO₂, we can calculate the overall ΔH for the reaction to form NO₂ from N₂ and O₂. Remember, when a reaction is multiplied, the ΔH must also be multiplied by the same factor. For instance, if the formation of NO₂ has an ΔH of 66.4 kJ for 2 moles, this value must be used to accurately represent the heat of reaction for the specified quantities.