Respuesta :
Explanation:
The given data is as follows.
   mass = 0.158 g,    volume = 100 ml
   Molarity = 1.0 M,    [tex]\Delta T[/tex] = [tex](32.8 - 25.6)^{o}C = 7.2^{o}C[/tex] Â
The given reaction is as follows.
     [tex]Mg(s) + 2HCl(aq) \rightarrow MgCl_{2}(aq) + H_{2}(g)[/tex] Â
So, moles of magnesium will be calculated as follows.
     No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]              Â
                = [tex]\frac{0.158 g}{24.305 g/mol}[/tex]
                = [tex]6.5 \times 10^{-3}[/tex]
                = 0.0065 mol
Now, formula for heat released is as follows.
       Q = [tex]m \times C \times \Delta T[/tex]
         = [tex]\text{volume} \times \text{density} \times C \times \Delta T[/tex]
         = [tex]100 ml \times 1.0 g/ml \times 4.184 \times 7.2^{o}C[/tex]
         = 3010.32 J
Hence, heat of reaction will be calculated as follows.
      [tex]\Delta H_{rxn} = \frac{\text{-heat released}}{\text{moles of Mg}}[/tex]
           = [tex]\frac{3010.32 J}{0.0065 mol}[/tex]
           = -4.63 J/mol
or, Â Â Â Â Â Â Â Â Â = [tex]-463 \times 10^{-5} kJ/mol[/tex] Â Â Â Â Â Â Â Â (as 1 kJ = 1000 J)
Thus, we can conclude that heat of given reaction is [tex]-463 \times 10^{-5}[/tex] kJ/mol. Â Â
