Question

The value of specific heat for copper is 390 J/kg⋅C∘, for aluminun is 900 J/kg⋅C∘, and for water is 4186 J/kg⋅C∘.

What will be the equilibrium temperature when a 215 g block of copper at 255 ∘C is placed in a 155 g aluminum calorimeter cup containing 845 g of water at 14.0 ∘C?

Express your answer using three significant figures.

Answer 1

Answer :

The first step is to convert the masses to kilograms
Cu = 0.215 kg
Al = 0.155 kg
H₂O = 0.845 kg

For Cu, Q = 0.215 x 390 x (255 – T_f) = 21381.75 – 83.85 xT_f

The initial temperature of aluminium calorimeter cup and water is 14⁰ C
For Al, Q = 0.155 x 900 x (T_f – 14) = 139.5 x T_f – 1953
For water, Q = 0.845 x 4186 x (T_f – 14) = 3537.17 x T_f – 49520.38
Total Q = 3676.67 x T_f – 51473.38

21381.75 – 83.85 x T_f = 3676.67 x T_f – 51473.38
3760.52 x T_f = 72855.13
T_f = 72855.13 ÷ 3760.52
The final temperature is approximately 19.37 ⁰C.