Can somebody help me?

The answers to your questions are given below

Explanation:

A. Fe + O2 —> Fe2O3

4Fe + 3O2 —> 2Fe2O3

The coefficients are 4, 3, 2

B. H2 + Cl2 —> HCl

H2 + Cl2 —> 2HCl

The coefficients are 1, 1, 2

C. Ag + H2S —> Ag2S + H2

2Ag + H2S —> Ag2S + H2

The coefficients are 2, 1, 1, 1

D. CH4 + O2 —> CO2 + H2O

CH4 + 2O2 —> CO2 + 2H2O

The coefficients are 1, 2, 1, 2

E. HgO —> Hg + O2

2HgO —> 2Hg + O2

The coefficients are 2, 2, 1

F. Co + H2O —> Co2O3 + H2

2Co + 3H2O —> Co2O3 + 3H2

The coefficients are 2, 3, 1, 3

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.