Question

A mass of 40 g of brass of specific heat capacity 0.85 Jg-1K-1 is heated in an oven and

then quickly transferred into 240g of water at 30℃ in a calorimeter of mass 60 g

and specific heat capacity 0.4 Jg-1K-1 . if the final temperature is 50℃, what was the

temperature of the oven?​

Answer 1

Hot Body (Brass) Cold Body (Water) Copper Calorimeter Note

m1 = 40 g m2 = 240 g m3 = 60 g (i) Temperature of oven is same as hot body

θ1 = ?

c1 = 0.85 J g-1k-1

θ2 = 30°C

c2 = 4.2 J g-1 k-1

θ2 = 30°C

c3 = 0.4 J g-1k-1

(ii) Temperature of calorimeter is same as cold body.

Final temperature, θ = 50°C

∴ Fall in temperature of hot body = θ1 - θ = (θ1 - 50)

Rise in temperature of cold body = θ - θ2 = (50 - 30) = 20

Heat lost by hot body = Heat gained by cold body + Copper calorimeter

m1C1 (θ1 - θ) = m2C2 (θ1 - θ) + m3C3 (θ1 - θ)

40 × 0.85 × θ - 50 = (240 × 4.2 × 20) + (60 × 0.4 × 20)

40 × 0.85 (θ - 50) = (20160 + 480)

(θ - 50) =

2064040×0.85

θ = 607.05 + 50 = 657.05°C

Temperature of oven = 657.05°C