In a steel plant, a 25g block of iron at 175 ˚C is dropped into 1 L of water at 20 ˚C in an insulated flask at atmospheric pressure. Calculate the final temperature of the system. The specific heat of iron is given by Ĥ(J/g)=17.3T(˚C).
What reference temperature was used as a basis for the entalpy formula?
Calculate the final temperature of the flask contents, assuming that the process is adiabatic, negligible evaporation of water occurs, negligile heat is transferred to the flask wall, and the specific enthalpy of liquid water at 1 atm and the given temperature is that of the saturated liquid at the same temperature. ( Enegy Balance reduces to Q= ΔH ).
Q = m c ∆T
Q = quantity of heat in joules (J)
m = mass of the substance acting as the environment in
c = specific heat capacity (4.19 for H2O) in J/(g oC)
∆T = change in temperature = Tfinal - Tinitial in oC
Heat lost by iron = heat gained by water
Specific Heat Capacity of Iron = 0.45 J/(g oC). I am doing calculation as you mentioned 17.3
25 x (175 -Tf ) x 17.3 = 1000 x 4.18 x (Tf-20)
75687.5 - 432Tf = 4180Tf - 83600
75687.5 + 83600 = 432Tf + 4180Tf
159287.5 = 4612 Tf
Tf = 34.53
Hence Final temperature of the system is 34.53 oC
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