Question

A worker needs to know the temperature inside an oven. He takes a 2 kg iron bar out of the oven and places it in a 1 kg aluminum container partially filled with 2 kg of water. If the water temperature rises from 21 ° C to 50 ° C, what was the temperature of the oven? Neglect other heat changes.

Answer 1

350°C

Step-by-step explanation:

Heat gained by water and aluminum = heat lost by iron

q₁ + q₂ = -q

m₁C₁ΔT₁ + m₂C₂ΔT₂ = -mCΔT

(1 kg) (900 J/kg/°C) (50°C − 21°C) + (2 kg) (4186 J/kg/°C) (50°C − 21°C) = -(2 kg) (449 J/kg/°C) (50°C − T)

(900 J/°C) (29°C) + 2 (4186 J/°C) (29°C) = -2 (449 J/°C) (50°C − T)

26,100 J + 242,788 J = -44,900 J + 898 (J/°C) T

898 (J/°C) T = 313,788 J

T = 350°C