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Homework Statement
What is the maximum mass of lead you could melt with 2000 J of heat, starting from 25 ∘C ? Lead melts at 328∘C , its specific heat is 128 J/(kg⋅K) , and its heat of fusion is 2.5×10^4 J/kg .
Homework Equations
Need to find both the mass in the heat of transformation (Q = MLf) and the mass that resonates with the outcome of Q=McT.
The Attempt at a Solution
With my first attempt, I believed that once I worked out both equations, I would subtract the product of Q=MLf from Q=McT, but that was incorrect. My work is as follows:
Q=McT
M=cT/Q
M= (128 J/kg*K * (328-25)K)/2000J = (128)(303)/2000; M = 19.39 kg.
(Difference in two temperatures of Celsius is equal to the difference in Kelvin, so I made the substitution from C to K here)
Q=MLf
M= Lf/Q; (2.5*10^4 J/kg)/(2000J) = 12.5kg
Because 12.5kg is the maximum mass that this heat can transform altogether, and 19.39kg is the mass that can be raised in temperature from the first equation, I subtracted one from the other. 19.39kg-12.5kg=6.89kg, but this is incorrect. Can anyone steer me in the correct direction for this problem?