Raw one valid lewis structure (including all lone pair electrons and any formal charges) for ch2n2. assume the atoms are arranged as shown below. h c n n h

In the trial structure (1st image below), every atom has an octet.

Valence electrons = 20

Valence electrons available = 4 + 2 +10 = 16

The trial structure has 4 electrons too many. The actual structure must have two double bonds or one triple bond.

The second image shows two possible Lewis structures.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

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