Question

Using Hess's law, calculate the delta H value for the following reaction:
FeO (s) + CO (g) → Fe (s) + 3CO₂
Use these three reactions:
1. Fe₂O₃ (s) + 3CO (g) → 2Fe (s) + 3CO₂ (g) ΔH = -25 kJ
2. 3Fe₂O₃ (s) + CO (g) → 2Fe₃O₄ (s) + CO₂ (g) ΔH = -47.0 kJ
3. Fe₃O₄ (s) + CO (g) → 3FeO (s) + CO₂ (g) ΔH = +38.0 kJ

Answer 1

Answer on Question #57013 - Chemistry - Other

Question:

Using Hess's law, calculate the delta H value for the following reaction:

$$\mathrm{FeO}(\mathrm{s}) + \mathrm{CO}(\mathrm{g}) \rightarrow \mathrm{Fe}(\mathrm{s}) + 3\mathrm{CO}_2$$

Use these three reactions:

1. $\mathrm{Fe_2O_3(s) + 3CO(g)\rightarrow 2Fe(s) + 3CO_2(g)\Delta H = -25kJ}$

2. $3\mathrm{Fe_2O_3(s)} + \mathrm{CO(g)}\rightarrow 2\mathrm{Fe_3O_4(s)} + \mathrm{CO_2(g)}\Delta H = -47.0\mathrm{kJ}$

3. $\mathrm{Fe_3O_4(s) + CO(g)\rightarrow 3FeO(s) + CO_2(g)\Delta H = +38.0kJ}$

Solution:

To get the reaction we need, we have to make some operations with the equations given :

1. Invert the second and third equation:

$$\begin{array}{l} (-II) 2\mathrm{Fe_3O_4(s)} + \mathrm{CO_2(g)} \rightarrow 3\mathrm{Fe_2O_3(s)} + \mathrm{CO(g)} \Delta H = +47.0\ \mathrm{kJ} \\ (-III) 3\mathrm{FeO}(\mathrm{s}) + \mathrm{CO_2(g)} \rightarrow \mathrm{Fe_3O_4(s)} + \mathrm{CO(g)} \Delta H = -38.0\ \mathrm{kJ} \\ \end{array}$$

2. Multiply the second result by two and sum with the (-2):

$$(-III*2-II) 6\mathrm{FeO}(\mathrm{s}) + 3\mathrm{CO_2(g)} \rightarrow 3\mathrm{CO(g)} + 3\mathrm{Fe_2O_3(s)} \Delta H = -38.0*2 + 47 = -29\ \mathrm{kJ}$$

3. Divide the obtained reaction by 3 and add the (I):

$$[(-III*2-II)/3 + I] 2\mathrm{FeO}(\mathrm{s}) + 2\mathrm{CO(g)} \rightarrow 2\mathrm{Fe}(\mathrm{s}) + 2\mathrm{CO_2(g)} \Delta H = -29/3 - 25 = -34.67\ \mathrm{kJ}$$

4. Divide the reaction obtained by 2:

$$[(-III*2-II)/3 + I]/2\mathrm{FeO}(\mathrm{s}) + \mathrm{CO(g)} \rightarrow \mathrm{Fe}(\mathrm{s}) + \mathrm{CO_2(g)} \Delta H = -54/2 = -17.33\ \mathrm{kJ}$$

Answer: -17.33 kJ

www.AssignmentExpert.com