Question

A 100. g iron rod is heated to an unknown initial temperature. While cooling down to a temperature of 25.0 degree C, the rod releases 600.2 J of energy. What was its initial temperature? (The specific heat of iron is 0.452 J/g degree C)
a) 38.3 J
b) 11.7 J
c) 27.7 J
d) 22.3 J

Answer 1

Answer: a)  $38.3^0C$

Explanation:

As we know that,  

$q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

where,

q = heat released  = -600.2 J

$m$ = mass of iron rod =100 g  

$T_{final}$ = final temperature =$25.^0C$

$T_{initial}$ = initial temperature = ?

$c$ = specific heat of iron = $0.452J/g^0C$

Now put all the given values in equation, we get

$-600.2J=100\times 0.452J/g^0C\times (25.0-T_{initial})^0C]$

$T_{initial}=38.3^0C$

Therefore, the initial temperature of iron rod was $38.3^0C$