Answer to Question #111932 in Molecular Physics | Thermodynamics for hayle

Question

A 1-kg block of ice is at -15° C. 4 x 105 J of heat is added to the ice block. NOTE: (a) should be divided into two parts: how much heat is needed to raise the temperature of the ice to 0 °C, and how much heat is required to melt it; then compare that sum total to 4.0 x 105 J (the specific heat to use for ice is provided in the accompanying sheet to this homework)

(a) Does it fully melt?
(b) What is the final overall temperature?

Answer 1

a)

$$Q_1=(1)(2060)(15)=30900\ J$$

$$Q_2=(1)(335000)=335000\ J$$

$$Q=335000+30900=365900\ J<400000\ J$$

So, all ice melted.

b)

$$(1)(4200)(T-0)=400000-365900$$

$$T=8.1\degree C$$