Sulfur reacts with oxygen to form sulfur dioxide [tex]\left( SO_2(g), \Delta H_f = -296.8 \text{ kJ/mol} \right)[/tex] according to the equation below.

[tex]\[ S(s) + O_2(g) \rightarrow SO_2(g) \][/tex]

What is the enthalpy change for the reaction?

Use [tex] \Delta H_{rxn} = \sum \left( \Delta H_{f, \text{products}} \right) - \sum \left( \Delta H_{f, \text{reactants}} \right) [/tex].

A. [tex] -593.6 \text{ kJ} [/tex]

B. [tex] -296.8 \text{ kJ} [/tex]

C. [tex] 296.8 \text{ kJ} [/tex]

D. [tex] 593.6 \text{ kJ} [/tex]



Answer :

To find the enthalpy change for the reaction, we shall use the given enthalpy of formation values and apply the formula:

[tex]\[ \Delta H_{rxn} = \sum \Delta H_{f,\text{products}} - \sum \Delta H_{f,\text{reactants}} \][/tex]

Let's identify the relevant enthalpy of formation values given in the problem:

- The enthalpy of formation for [tex]\( \text{SO}_2(g) \)[/tex] is [tex]\( \Delta H_f = -296.8 \ \text{kJ/mol} \)[/tex].
- The enthalpy of formation for [tex]\( \text{S(s)} \)[/tex] and [tex]\( \text{O}_2(g) \)[/tex] are both [tex]\( 0 \ \text{kJ/mol} \)[/tex] because they are elements in their standard states.

Now, let's write the reaction:

[tex]\[ \text{S(s)} + \text{O}_2(g) \rightarrow \text{SO}_2(g) \][/tex]

We calculate the sum of the enthalpies of formation for the reactants and products:

- For the products:
[tex]\[ \sum \Delta H_{f,\text{products}} = \Delta H_f(\text{SO}_2(g)) = -296.8 \ \text{kJ/mol} \][/tex]

- For the reactants:
[tex]\[ \sum \Delta H_{f,\text{reactants}} = \Delta H_f(\text{S(s)}) + \Delta H_f(\text{O}_2(g)) = 0 \ \text{kJ/mol} + 0 \ \text{kJ/mol} = 0 \ \text{kJ/mol} \][/tex]

Now, subtract the sum of the reactants' enthalpies from the sum of the products' enthalpies:

[tex]\[ \Delta H_{rxn} = \sum \Delta H_{f,\text{products}} - \sum \Delta H_{f,\text{reactants}} = -296.8 \ \text{kJ/mol} - 0 \ \text{kJ/mol} = -296.8 \ \text{kJ/mol} \][/tex]

So, the enthalpy change for the reaction is:

[tex]\[ \Delta H_{rxn} = -296.8 \ \text{kJ/mol} \][/tex]

Thus, the correct answer is [tex]\( \boxed{-296.8 \ \text{kJ}} \)[/tex].