Which chemical reaction model is flawed and why?
a) 4c2+s8 -> 4cs2
b) 2fe+3cl2 -> 2fecl3
c) 2na+cl2 -> 2nacl
d) p4o10+6h2o -> 4h3po4

A) 4C2+S8 -> 4CS2

Explanation:

The chemical equation

4C2+S8 -> 4CS2 is flawed because the equation is not balanced i.e the carbon atom at the reactant is not equal to that of the product and for a chemical reaction to be a balanced equation, the number of atoms of elements at the reactants must be equal to that of the product.

As you can see, there are 8 atoms of carbon(C) at the reactant while we have only 4 carbon atoms at the product therefore making the equation unbalanced.

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.