For which one of the following equations is Δ H re a c t i o n ∘ reaction equal to Δ H ∘ f for the product :-

Question

For which one of the following equations is Δ H re a c t i o n ∘ ​ reaction equal to Δ H ∘ f for the product :-

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Question Explanation:

Identify the equation for which $Δ H^{\circ}$ is equal to the standard enthalpy of formation $(Δ H_{f}^{o})$ for the product.

Concept:

This question is based on standard enthalpy of formation.

Solution:

The standard enthalpy of formation requires one mole of product formed from elements in their standard states.

(1). $N (g) + O (g) \to NO (g)$ : Reactants are gaseous atoms, not standard states.

(2). $CH_{4} (g) + 2 Cl_{2} (g) \to CH_{2} Cl_{2} (l) + 2 HCl (g)$ : Reactant $CH_{4}$ is a compound.

(3). $Xe (g) + 2 F_{2} (g) \to XeF_{4} (g)$ : Forms one mole of $XeF_{4} (g)$ from elements $Xe (g)$ and $F_{2} (g)$ in their standard states. Correct.

(4). $2 CO (g) + O_{2} (g) \to 2 CO_{2} (g)$ : Forms two moles of product from a compound.

Chemistry - Thermochemistry Question with Solution | TestHub

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