In: Chemistry
A 2.43 g lead weight, initially at 10.6 ∘C, is submerged in 7.78 g of water at 52.9 ∘C in an insulated container. What is the final temperature of both the weight and the water at thermal equilibrium?
Mass of Pb = 2.43 g
Initial temperature = 10.6oC
Mass of water = 7.78 g
Temperature of water = 52.9oC
Heat released by water = m c T
Heat released by water = 0.00778 x 4186 x (52.9 –
Tf)
Heat absorbed by lead = m c T
Heat absorbed by lead = 0.00243 x 128 x (Tf –
10.6)
Heat released by water = Heat absorbed by lead
0.00778 x 4186 x (52.9 – Tf) = 0.00243 x 128 x
(Tf – 10.6)
(0.00778 x 4186 x 52.9) – (0.00778 x 4186 x Tf) =
(0.00243 x 128 x Tf) – (0.00243 x 128 x 11.1)
Add (0.00778 * 4186 * Tf) to both sides
(0.00778 x 4186 x 52.9) = (0.00778 x 4186 x Tf) +
(0.00243 x 128 x Tf) – (0.00243 x 128 x 10.6)
Add (0.00243 x 128 x 10.6) to both sides
(0.00243 x 128 x 10.6) + (0.00778 x 4186 x 52.9) = (0.00778 x 4186
x Tf) + (0.00243 x 128 x Tf)
Divide both sides by (0.00778 x 4186) + (0.00243 x 128)
[(0.00243 x 128 x 10.6) + (0.00778 x 4186 x 52.9)] ÷ [(0.00778 x
4186) + (0.00243 x 128)] = Tf
Tf = 52.49oC