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The standard enthalpics of formation of ...

The standard enthalpics of formation of `CO,NO_(2)` and `CO_(2)` are `110.5 KJ mol^(-1), -33.2 KJ mol^(-1)` and `-393.5 KJ mol^(1)` respectively. The standard enthalpy of the reaction
`4CO(g)+2NO_(2)(g)to4CO_(2)(g)+N_(2(g))` is

A

`-1065.6kJ`

B

`-200kJ`

C

`-700kJ`

D

`850kJ`

Text Solution

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The correct Answer is:
To calculate the standard enthalpy of the reaction: \[ 4 \text{CO}(g) + 2 \text{NO}_2(g) \rightarrow 4 \text{CO}_2(g) + \text{N}_2(g) \] we will use the standard enthalpies of formation of the reactants and products provided in the question. ### Step-by-Step Solution: 1. **Write the standard enthalpy of formation reactions for each compound:** - For Carbon Monoxide (CO): \[ \text{C}(s) + \frac{1}{2} \text{O}_2(g) \rightarrow \text{CO}(g) \quad \Delta H_f^\circ = -110.5 \, \text{kJ/mol} \] - For Nitrogen Dioxide (NO2): \[ \text{N}_2(g) + \frac{1}{2} \text{O}_2(g) \rightarrow \text{NO}_2(g) \quad \Delta H_f^\circ = -33.2 \, \text{kJ/mol} \] - For Carbon Dioxide (CO2): \[ \text{C}(s) + \text{O}_2(g) \rightarrow \text{CO}_2(g) \quad \Delta H_f^\circ = -393.5 \, \text{kJ/mol} \] 2. **Adjust the reactions to match the stoichiometry of the given reaction:** - Multiply the formation reaction of CO by 4: \[ 4 \text{C}(s) + 2 \text{O}_2(g) \rightarrow 4 \text{CO}(g) \quad \Delta H_f^\circ = 4 \times (-110.5) = -442 \, \text{kJ} \] - Multiply the formation reaction of NO2 by 2: \[ 2 \text{N}_2(g) + O_2(g) \rightarrow 2 \text{NO}_2(g) \quad \Delta H_f^\circ = 2 \times (-33.2) = -66.4 \, \text{kJ} \] - Multiply the formation reaction of CO2 by 4 (no change in sign): \[ 4 \text{C}(s) + 4 \text{O}_2(g) \rightarrow 4 \text{CO}_2(g) \quad \Delta H_f^\circ = 4 \times (-393.5) = -1574 \, \text{kJ} \] 3. **Reverse the formation reactions of CO and NO2 because they are reactants in the target reaction:** - For CO: \[ 4 \text{CO}(g) \rightarrow 4 \text{C}(s) + 2 \text{O}_2(g) \quad \Delta H = +442 \, \text{kJ} \] - For NO2: \[ 2 \text{NO}_2(g) \rightarrow 2 \text{N}_2(g) + O_2(g) \quad \Delta H = +66.4 \, \text{kJ} \] 4. **Add the enthalpy changes of the adjusted reactions:** - The total enthalpy change for the reaction is: \[ \Delta H = (+442) + (+66.4) + (-1574) \] - Simplifying this gives: \[ \Delta H = 442 + 66.4 - 1574 = -1065.6 \, \text{kJ} \] ### Final Answer: The standard enthalpy of the reaction \( 4 \text{CO}(g) + 2 \text{NO}_2(g) \rightarrow 4 \text{CO}_2(g) + \text{N}_2(g) \) is \(-1065.6 \, \text{kJ}\).

To calculate the standard enthalpy of the reaction: \[ 4 \text{CO}(g) + 2 \text{NO}_2(g) \rightarrow 4 \text{CO}_2(g) + \text{N}_2(g) \] we will use the standard enthalpies of formation of the reactants and products provided in the question. ### Step-by-Step Solution: ...
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