Given the thermochemical equations below, What is the standard heat of formation of CuO(s)? 2 Cu2O(s) + O2(g) ---> 4 CuO(s) ∆H° = -287.9 kJ Cu2O(s) ---> CuO(s) + Cu(s) ∆H° = 11.3 kJ

-130KJ is the standard heat of formation of CuO.

Explanation:

The standard heat of formation or enthalpy change can be calculated by using the formula:

standard heat of formation of reaction = standard enthalpy of formation of product - sum of enthalpy of product formation

Data given:

Cu2O(s) ---> CuO(s) + Cu(s) ∆H° = 11.3 kJ

2 Cu2O(s) + O2(g) ---> 4 CuO(s) ∆H° = -287.9 kJ

CuO + Cu ⇒ Cu2O (-11.3 KJ)      ( Formation of Cu2O)

When 1 mole Cu20 undergoes combustion 1/2 moles of oxygen is consumed.

Cu20 + 1/2 02 ⇒ 2CuO (I/2 of 238.7 KJ) or 119.35 KJ

So standard heat of formation of  formation of Cu0 as:

Cu + 1/2 02 ⇒ CuO

putting the values in the equation

ΔHf = ΔH1 + ΔH2     (ΔH1 + ΔH2  enthalapy of reactants)

heat of formation = -11.3 + (-119.35)

                            = - 130.65kJ

-130.65 KJ is the heat of formation of CuO in the given reaction.

The standard heat of formation of CuO is -310.5 kJ.

Explanation:

To get the standard heat of formation, we have to multiply the second equation by 2 and reverse it and add it to the first equation, we will get the required compound.

2 Cu₂O(s) + O₂(g) → 4 CuO(s) ∆H° = -287.9 kJ 1

Cu₂O(s) → CuO(s) + Cu(s)        ∆H° = 11.3 kJ 2

Now multiplying the equation 2 by 2 and reversing it, we will get,

2 CuO(s) + 2 Cu(s) → 2 Cu₂O(s)     ∆H° = -22.6 kJ 3

Now adding eq. 3 with eq. 1 we will get the formation of CuO as,

2 Cu(s) + O₂(g) → 2 CuO(s) ∆H° = -22.6 kJ - 287.9 kJ = -310.5 kJ

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.