Which of the following ions is in the lowest oxidation state?

C. Fe in Fe₂O₃

Explanation:

The sum of the oxidations states times the atomicity is equal to the charge of the molecule.

A.

2.H + 1.P + 4.O = -1

2.(1+) + 1.P + 4.(2-) = -1

P = +5

B.

2.Cr + 7.O = -2

2.Cr + 7.(-2) = -2

2.Cr = 12

Cr = +6

C.

2.Fe + 3.O = 0

2.Fe + 3.(-2) = 0

2.Fe = 6

Fe = +3

Fe has the lowest oxidation state (+3).

yea hi

explanation:

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.