When the copper soldering iron cools down to 20 • s, dec. 30.4 KJ of energy.

When the copper soldering iron cools down to 20 • s, dec. 30.4 KJ of energy. To what temperature was the soldering iron heated if its weight is 200g?

Initial data: t1 (temperature reached by the soldering iron during cooling) = 20 ºС; Q (heat generated by the soldering iron) = 30.4 kJ = 30.4 * 10 ^ 3 J; m (soldering iron weight) = 200 g or 0.2 kg.

Reference data: С (specific heat of copper) = 400 J / (kg * K).

The temperature to which the soldering iron was heated can be expressed from the formula: Q = C * m * (t2 – t1).

t2 – t1 = Q / (C * m) and t2 = Q / (C * m) + t1.

Let’s do the calculation:

t2 = 30.4 * 10 ^ 3 / (400 * 0.2) + 20 = 400 ºС.

Answer: The copper soldering iron was heated to 400 ºC.