The specific heat of the metal was determined following of the Experiment Proced
ID: 962600 • Letter: T
Question
The specific heat of the metal was determined following of the Experiment Procedure in this experiment. Complete the following table for Trial 1 (See Report Sheet.) for determining the specific heat of the metal. Record the calculated values with the correct number of significant figures. 5. The enthalpy of solution for the dissolving of a KBr sample was determined following Part C iof the Experimental Procedure in this experiment. Complete the following table for Trial 1 (See Report Sheet.) for determining the enthalphy of solution of KBr.Explanation / Answer
Solution.
4. The temperature change between the final temperature (T2) and the initial temperature (T1) is given by
T = T2-T1;
The temperature change of water is
T = 24.6-22.0 = 2.6 °C;
The temperature change of metal is
T =24.6 - 99.4 = -74.8 °C;
The heat gained or lost (Q) for a mass (m) and specific heat (c) can be calculated by a formula
Q = cmT;
Heat gained by water:
Q = 4200J/(kg°C)*0.1 kg*2.6°C = 1092 J;
As the metal gave all its heat to water, the heat lost by the metal is the same as the heat gained by water, but with the opposite sign, and the specific heat is
c = Q/(mT) =-1092/(20.94*(-74.8)) = 0.697 J/(g°C).
5. The amount of salt is n = m/M = 5 g/(119 g/mol) = 0.042 mol;
The temperature change of the solution is
T = 18.1-25.0 = -6.9 °C;
Heat change of water is Q = cmT = 4.2 J/(g°C) * 25 g * (-6.9 °C) = -724.5 J;
Heat change of salt is Q = cmT = 0.439 J/(g°C) * 5 g * (-6.9 °C) = -15.2 J;
Total enthalpy change is H = 724.5+15.2 = 739.7 J;
The specific enthalpy change is (739.7 J) / (0.042 mol) = 17610 J/mol.
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