This question is about enthalpy changes. A student wanted to use Hess's Law to determine the enthalpy change, $$\(\Delta_{\mathrm{r}} H_{1}\)$$, in $$\(\mathrm{kJ} \mathrm{mol}^{-1}\)$$, for Reaction 1. Calculate the enthalpy change of reaction, $$\(\Delta_{r} H_{1}\)$$, for Reaction 1. Use your answer to (b), the data provided and the enthalpy cycle shown. [If you did not calculate an answer to (b), use a value of $$\(-100 \mathrm{~kJ} \mathrm{~mol}^{-1}\)$$. This is not the correct answer.] (2) Data $$\(\mathrm{Mg}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{MgCl}_{2}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})\)$$ $$\(\Delta_{\mathrm{r}} \mathrm{H}=-462 \mathrm{~kJ} \mathrm{~mol}^{-1}\)$$ $$\(\mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l})\)$$ $$\(\Delta_{\mathrm{f}} H=-286 \mathrm{~kJ} \mathrm{~mol}^{-1}\)$$ $$\(-\)$$

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