please post an image of how you worked this out. step by step. please!? 2. Consi
ID: 525022 • Letter: P
Question
please post an image of how you worked this out. step by step. please!?
2. Consider the following three reactions:
2 Fe (s) + 6 HCl (aq) 2 FeCl3 (aq) + 3 H2 (g) ......HA
Fe2O3 (s) + 6 HCl (aq) 2 FeCl3 (aq) + 3 H2O (l) ......HB
2 H2 (g) + O2 (g)
2 H2O(l) ...HC
Show how these be summed together according to Hess’s Law to determine H for the combustion of iron (target equation shown below). Also show clearly how the H values of each of the three reactions must be manipulated to determine the enthalpy of combustion of iron.
4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s) H = ?
3. Using tabulated Hf° values in the text, determine the enthalpy change (in kJ/mol) that occurs during the formation of water from its elements as described by the equation:
2 H2 (g) + O2 (g) 2 H2O (l) H = ?
Note that this value (and the equation) will be used in your data analysis for this lab.
Explanation / Answer
2 Fe (s) + 6 HCl (aq) 2 FeCl3 (aq) + 3 H2 (g) ......HA
Fe2O3 (s) + 6 HCl (aq) 2 FeCl3 (aq) + 3 H2O (l) ......HB
2 H2 (g) + O2 (g) 2 H2O(l) ...HC
Target is;4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s) H = ?
from reaction (1), we need 4Fe, so multiply by 2
4Fe (s) + 12HCl (aq) 4FeCl3 (aq) + 6H2 (g) ...... 2xHA
we need to cancel HCl, so invert (2) and multiply by 2
4FeCl3 (aq) + 6H2O (l) 2Fe2O3 (s) + 12HCl (aq) ......-2xHB
we need to cancel water so multiply (3) by 3
6H2 (g) + 3O2 (g) 6H2O(l) ...3xHC
total reaction:
4Fe (s) + 12HCl (aq) + 4FeCl3 (aq) + 6H2O (l) + 6H2 (g) + 3O2 --> 4FeCl3 (aq) + 6H2 (g) + Fe2O3 (s) + 12HCl (aq) + 6H2O(l)
Htotal = 2xHA -2xHB + 3xHC
cancel common terms:
4Fe (s) + 12HCl (aq) + 4FeCl3 (aq) + 6H2O (l) + 6H2 (g) + 3O2 --> 4FeCl3 (aq) + 6H2 (g) + Fe2O3 (s) + 12HCl (aq) + 6H2O(l)
We get
4Fe (s) + 3O2 --> Fe2O3 (s) H = 2xHA -2xHB + 3xHC
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