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An original reaction and enthalpy is given below.
[tex]$
\begin{array}{r}
Fe_2O_3(s) + 3CO(g) \rightarrow 2Fe(s) + 3CO_2(g) \\
\Delta H = -23.44 \, \text{kJ}
\end{array}
$[/tex]

What is the enthalpy for the altered reaction below?
[tex]$
\begin{array}{c}
3Fe_2O_3(s) + 9CO(g) \rightarrow 6Fe(s) + 9CO_2(g) \\
\Delta H = [?] \, \text{kJ}
\end{array}
$[/tex]

Enter either a + or - sign and the magnitude. Use significant figures.


Sagot :

To determine the enthalpy change for the altered reaction, we need to understand how changing the coefficients of a reaction affects its enthalpy change.

Given the original reaction:
[tex]\[ \text{Fe}_2\text{O}_3(s) + 3 \text{CO}(g) \rightarrow 2 \text{Fe}(s) + 3 \text{CO}_2(g) \][/tex]
with [tex]\(\Delta H = -23.44 \, \text{kJ}\)[/tex],

we see that this reaction has a specific enthalpy change associated with the transformation of 1 mole of [tex]\(\text{Fe}_2\text{O}_3\)[/tex].

Consider the altered reaction:
[tex]\[ 3 \text{Fe}_2\text{O}_3(s) + 9 \text{CO}(g) \rightarrow 6 \text{Fe}(s) + 9 \text{CO}_2(g) \][/tex]

We notice that the coefficients of this altered reaction are exactly 3 times the coefficients of the original reaction. When a reaction's coefficients are multiplied by a factor, the enthalpy change for the reaction is also multiplied by that same factor.

Thus, if the original enthalpy change [tex]\(\Delta H\)[/tex] is [tex]\(-23.44 \, \text{kJ}\)[/tex], for the altered reaction (with coefficients multiplied by 3), the enthalpy change [tex]\(\Delta H'\)[/tex] will be:
[tex]\[ \Delta H' = 3 \times (\Delta H_{\text{original}}) = 3 \times (-23.44 \, \text{kJ}) \][/tex]

Calculating this gives:
[tex]\[ \Delta H' = -70.32 \, \text{kJ} \][/tex]

Therefore, the enthalpy change for the altered reaction is:
[tex]\[ \Delta H = -70.32 \, \text{kJ} \][/tex]