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magnesium12
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Homework Statement
The standard entropy of lead at 25C is S(298)=64.80 J/Kmol.
The heat capacity of solid lead is Cp(s) = 22.13 + .01172T + 0.96x105T-2.
The heat capacity of liquid lead is Cp(l) = 32.51 - 0.00301T
Melting point is 327.4C
Heat of fusion is 4770J/mol.
Calculate the standard entropy of liquid lead at 500C.
Homework Equations
ΔS(500) = S(298) + ∫(Cp(s)/T)dT + ΔHfus/T + ∫(Cp(l)/T)dT
ΔS(500) = ∫(Cp(s)/T)dT + ΔHfus/T + ∫(Cp(l)/T)dT
The Attempt at a Solution
I'm just wondering which equation to use?
At first I thought the equation was just ΔS(500) = ∫(Cp(s)/T)dT + ΔHfus/T + ∫(Cp(l)/T)dT but the question includes the standard entropy at 25C, so do I have to account for that too by using ΔS(500) = S(298) + ∫(Cp(s)/T)dT + ΔHfus/T + ∫(Cp(l)/T)dT? But shouldn't the initial entropy not matter since entropy is a state function?
And if I do have to account for entropy at 25C, does that entropy stay the same up to the melting point so I wouldn't need to account for the ∫(Cp(s)/T)dT