The final temperature = 36 °C
Further explanation
The balanced combustion reaction for C₆H₆
2C₆H₆(l)+15O₂(g)⇒ 12CO₂(g)+6H₂O(l) +6542 kJ
MW C₆H₆ : 78.11 g/mol
mol C₆H₆ :
[tex]\tt \dfrac{8.5}{78.11}=0.109[/tex]
Heat released for 2 mol C₆H₆ =6542 kJ, so for 1 mol
[tex]\tt \dfrac{0.109}{2}\times 6542=356.539~kJ/mol[/tex]
Heat transferred to water :
Q=m.c.ΔT
[tex]\tt 356.539=5.691~kg\times 4.18~kj/kg^oC\times (t_2-21)\\\\t_2-21=15\rightarrow t_2=36^oC[/tex]
