Respuesta :
Explanation:
The given data is as follows.
Mass of Mg = 1.30 g, Molarity = 5 for HCl, Volume = 150 mL
Density = 1.1 g/mL
Change in temperature (dT) = [tex](52 - 22)^{o}C = 30^{o}C[/tex]
[tex]C_{p}[/tex] = 345 [tex]J/^{o}C[/tex]
Hence, the energy balance will be as follows.
[tex]-Q_{rxn} = Q_{calorimeter} + Q_{water}[/tex]
[tex]Q_{rxn} = H_{rxn}/mol[/tex]
[tex]H_{Rxn} = Q_{Rxn}/mol[/tex]
Moles of Mg = [tex]\frac{mass}{\text{molecular mass}}[/tex]
= [tex]{1.3}{24.3}[/tex]
= 0.05349 mol of Mg
[tex]Q_{calorimter} = C \times dT[/tex]
= [tex]345 J/^{o}C \times 30^{o}C[/tex]
= 10350 J
[tex]Q_{water} = m \times C \times (T_{f} - T_{i})[/tex]
= [tex]150 \times 1.1 \times 4.184 \times 30^{o}C[/tex]
= 20710.8
[tex]-Q_{rxn}[/tex] = (20710.8 + 10350) J
[tex]Q_{rxn}[/tex] = -31060.8 J
Therefore, calculate the value of [tex]\Delta H[/tex] of the reaction as follows.
[tex]Q_{rxn} = H_{rxn}/mol[/tex]
[tex]H_rxn = \frac{-31060.8}{0.05349}[/tex]
[tex]H_{Rxn}[/tex] = -580684.24 J/mol
or, [tex]H_{Rxn} = -580.68 kJ/mol[/tex] (as 1 kJ = 1000 J)
Thus, we can conclude that value of [tex]\Delta H[/tex] of the reaction under given conditions is -580.68 kJ/mol.
