Question

If 8.500 g CH is burned and the heat produced from the burning is added to 5691 g of water at 21 °C, what is the final

temperature of the water?

Answer 1

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 :

`\tt (8.5)/(78.11)=0.109`

Heat released for 2 mol C₆H₆ =6542 kJ, so for 1 mol

`\tt (0.109)/(2)* 6542=356.539~kJ/mol`

Heat transferred to water :

Q=m.c.ΔT

`\tt 356.539=5.691~kg* 4.18~kj/kg^oC* (t_2-21)\\\\t_2-21=15\rightarrow t_2=36^oC`