Exercise 7 | Thermochemistry

A 35.0 g sample of aluminum at 25.0°C is placed in 100.0 g of water at 65.0°C.

The final temperature of water + aluminum is 58.3°C.

Calculate the specific heat of aluminum.


Data: cP (water) = 417.9 J.K-1

Water: higher temperature ⇒ transfer energy to aluminum

Aluminum: lower temperature ⇒ gain energy from water


qlost (water) + qgained (aluminum) = 0

cp (water) x (Tf – Ti (water)) = - cp (Al) x (Tf – Ti (Al))

⇒ cp (water) x (Tf – Ti (water)) = - cs (Al) x m (Al) x (Tf – Ti (Al))

⇒ cs (Al) = - cP (water) × Tf - Ti (water)m (Al) × Tf - Ti (Al)

⇒ cs (Al) = - 417.9 × (331.3 - 338)35.0 × (331.3 - 298)

⇒ cs (Al) = 2.40 J.g-1.K-1