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Identify the reaction for which Delta H ...

Identify the reaction for which `Delta H != Delta E`

A

`s("rhombic") + O_(2)(g) rarr SO_(2)(g)`

B

`N_(2)(g) + O_(2)(g) rarr 2NO(g)`

C

`H_(2)(g) + Cl_(2)(g) rarr 2HCl(g)`

D

`CO(g) + 1/2 O_(2)(g) rarr CO_(2)(g)`

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The correct Answer is:
To solve the problem of identifying the reaction for which ΔH ≠ ΔE, we need to understand the relationship between enthalpy (ΔH) and internal energy (ΔE) in the context of chemical reactions. Here’s a step-by-step breakdown of the solution: ### Step 1: Understand the Definitions - **ΔH (Enthalpy Change)**: This is the heat change at constant pressure. - **ΔE (Internal Energy Change)**: This is the heat change at constant volume. ### Step 2: Identify the Relationship The relationship between ΔH and ΔE can be expressed with the formula: \[ \Delta E = \Delta H - \Delta N_g RT \] where: - \( \Delta N_g \) = change in the number of moles of gas (moles of gaseous products - moles of gaseous reactants) - \( R \) = universal gas constant - \( T \) = temperature in Kelvin ### Step 3: Determine Conditions for ΔH ≠ ΔE For ΔH to not equal ΔE, the term \( \Delta N_g RT \) must be non-zero. This occurs when there is a change in the number of moles of gas during the reaction. ### Step 4: Analyze the Given Reactions We need to analyze the four options provided to find which one has a non-zero \( \Delta N_g \). 1. **First Reaction**: - Reactants: 1 mole of solid + 1 mole of gas - Products: 1 mole of gas - \( \Delta N_g = 1 - 1 = 0 \) 2. **Second Reaction**: - Reactants: 1 mole of gas + 1 mole of gas - Products: 2 moles of gas - \( \Delta N_g = 2 - 2 = 0 \) 3. **Third Reaction**: - Reactants: 1 mole of gas + 1 mole of gas - Products: 2 moles of gas - \( \Delta N_g = 2 - 2 = 0 \) 4. **Fourth Reaction**: - Reactants: 1 mole of CO (gas) + 1 mole of O2 (gas) - Products: 1 mole of CO2 (gas) - \( \Delta N_g = 1 - (1 + 1/2) = 1 - 1.5 = -0.5 \) (which is not zero) ### Step 5: Conclusion From the analysis, the fourth reaction is the only one where \( \Delta N_g \) is not equal to zero. Therefore, for this reaction, ΔH ≠ ΔE. ### Final Answer The reaction for which ΔH ≠ ΔE is the fourth option. ---

To solve the problem of identifying the reaction for which ΔH ≠ ΔE, we need to understand the relationship between enthalpy (ΔH) and internal energy (ΔE) in the context of chemical reactions. Here’s a step-by-step breakdown of the solution: ### Step 1: Understand the Definitions - **ΔH (Enthalpy Change)**: This is the heat change at constant pressure. - **ΔE (Internal Energy Change)**: This is the heat change at constant volume. ### Step 2: Identify the Relationship The relationship between ΔH and ΔE can be expressed with the formula: ...
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