What is the enthalpy change for the following equation? [closed]








**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
 
 






---








 **Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistry Stack Exchange?](https://chemistry.meta.stackexchange.com/questions/141/how-do-i-ask-homework-questions-on-chemistry-stack-exchange)




Closed 8 years ago.








[Improve this question](/posts/27604/edit) 



The equation we need it to change to 
\[\ce{FeO + CO ->Fe + CO2}\]


The three equations and delta heat:


\[
\begin{align\*}
\ce{3Fe2O3 + CO &-> 2Fe3O4 + CO2} &\Delta H=-47.0\ \mathrm{kJ}\\
\ce{Fe2O3 + 3CO &-> 2Fe + 3CO2} &\Delta H=-25.0\ \mathrm{kJ}\\
\ce{Fe3O4 + CO &-> 3FeO + CO2} &\Delta H= 19.0\ \mathrm{kJ}
\end{align\*}
\]


What is the enthalpy change and how to combine the 3 equations to make the above equation? (Please show work)


Thank you,
 Tiffany





> 
> […] how to combine the 3 equations […]
> 
> 
> 


### **Equations** is the keyword!


This is just an example on how to solve a system of linear equations, disguised as a chemistry problem.


If the calculation with $\ce{FeO}$, $\ce{CO}$, $\ce{Fe}$, $\ce{CO2}$, etc. feels strange, just translate them to $x\_1$, $x\_2$, $x\_3$, $x\_4$, etc.


The question for the enthalpy of the first reaction therefore is equivalent to finding the solution for


\[y = x\_3 + x\_4 - x\_1 - x\_2 \]


### How to work in the other equations?


\[\ce{3Fe2O3 + CO -> 2Fe3O4 + CO2} \quad\quad\Delta H=-47.0\ \mathrm{kJ}\]


You have the reactants, the products and the enthalpy: translate that to a mathematical equation following the naming scheme introduced above:
\[2x\_6 + x4 - x\_2 - 3x\_5 = -47.0\]
Do the same for the other two equations, rearrange and try to solve the equation system.


 1