Consider the following hypothetical reaction D and E occurring in two steps to form G:

(1) D + E → F           ΔH° = +50 kJ/mol

(2) F + E → G         ΔH° = +100 kJ/mol

In the following Hess's law diagram, identify the arrow that corresponds to each step and determine the arrow that corresponds to the overall reaction. Identify the location of the products and the reactants.

Consider the formation of X and X forming which occurs in two steps as shown below: 

(i) W + 2X → 2Y         ΔH° = +100 kJ

(ii) X + 2Y → 2Z         ΔH° = –60 kJ 

(iii) W + 3X → 2Z       ΔH° = ?

Select the Hess's law diagram that best depicts the individual reactions and the overall process.

Select the correct addition of (i) and (ii) to get (iii)

(i) POCl₃ + Cl₂ → PCl₅ + 1/2 O₂ 

(ii) PCl₃ + Cl₂ → PCl₅

(iii) 2 POCl₃ → 2 PCl₃ + O₂

a.

POCl₃ + Cl₂  → PCl₅ + 1/2 O₂

PCl₃ + 1/2 O₂ → POCl₃ 

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PCl₃ + Cl₂ → PCl₅ 

b.

POCl₃ + Cl₂  → PCl₅ + 1/2 O₂

PCl₅ → PCl₃ + Cl₂

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POCl₃ → PCl₃ + 1/2 O₂

c.

2 [ POCl₃ + Cl₂  → PCl₅ + O₂ ]

2 [ PCl₃ + O₂ → 2 POCl₃ ]

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2 POCl₃ → 2 PCl₃ + O₂

d.  

2 [ POCl₃ + Cl₂  → PCl₅ + 1/2 O₂ ]

2 [ PCl₅ → PCl₃ + Cl₂ ]

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2 POCl₃ → 2 PCl₃ + O₂

Given the following data:

H₂(g) + 1/2 O₂(g) → H₂O(l)     ΔH = –285.8 kJ

N₂O₅(g) + H₂O(l) → 2 HNO₃(l)     ΔH = –76.6 kJ

1/2 N₂(g) + 3/2 O₂(g) + 1/2 H₂(g)    ΔH = –174.1 kJ

Calculate ΔH for 2 N₂O₅(g) → 2 N₂(g) + 5 O₂(g)

The reaction of P₄(g) and chlorine gas to form PCl₅(g) has a ΔH = –433.8 kJ/mol. On the other hand, the reaction of PCl₃(g) and chlorine gas to form PCl₅(g) has a ΔH = –87.9 kJ/mol. In these conditions, what is the enthalpy of the formation of PCl₃(g)?

Consider the reaction A + B ⇌ 2 C, K = 1.93 × 10³.

Calculate K for 4 C ⇌ 2 A + 2 B.

Calculate the enthalpy change for the hypothetical reaction

A(s) + 2 B₂(g) → AB₄(g)

Given the enthalpy values for the following reactions

AB₄(g) + 2 C₂(g) → AC₂(g) + 2 B₂C(l)

ΔH = −790.2 kJ

A(s) + C₂(g) → AC₂(g)

ΔH = −291.5 kJ

B₂(g) + 1/2 C₂(g) → B₂C (g)

ΔH = −175.5 kJ