What is the particle unit for so42-?

The particle unit is an ion.

Explanation: The unit which is common used for the substances is Mole. 1 mole of anything equals to Avogadro number which is .

For example, 1 mole of an electron equals to electrons,

1 mole of an atom equals to atoms.

So, 1 mole equals to particles.

is sulfate ion. So, the particle unit for this will be an ion.

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.