If 8.700 g of c6h6 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?

C₆H₆ is benzene which has a molar mass of 78 g/mol. When benzene is burned, the reaction is called combustion. The heat produced in this reaction is called the heat of combustion. For benzene, the heat of combustion is - 3271 kJ/mol.

Heat of benzene = (8.7 g) (1 mol/78 g) (-3271 kJ/mol) = - 364.84 kJ

By conservation of energy,

Heat of benzene = - Heat of water

where

Heat of Water = mCp (Tf - T₀)

where Cp for water is 4.187 kJ/kg·°C

Thus,

-364.84 kJ = - (5691 g) (1 kg/1000 g) (4.187 kJ/kg·°C) (Tf - 21)

Tf = 36.31°C