Really need help with this question!! There is no initial temp for the metal Cal
ID: 1051800 • Letter: R
Question
Really need help with this question!! There is no initial temp for the metal
Calculate the specific heat capacity of the unknown metal in J/xK.
[Unknown metal]
Mass of metal: 33.996g
Temp of boiling water: 98.0 C
volume of water in cup: 50 mL
Temp of water in cup: 25.1 C
Final temp of the system: 29.2 C
Extra information:
(Qmetal) = -959.5 J (heat lost by unknown metal)
(Qcal) = 102.6 J (heat gained by calorimeter after adding unknown metal)
(Qwater) = 856.9 J (heat gained by the water in the calorimeter after adding unknown metal)
Explanation / Answer
Total heat lost by the metal = - 959.6 J (the -ve sign indicates that heat is being lost)
Out of 959.6 J heat released by the metal, 102.6 J is absorbed by the calorimeter and 856.9 J is absorbed by water.
A bit of clarifications:
Mass of metal: 33.996g
Temp of boiling water: 98.0 0C - 1 =
volume of water in cup: 50 mL - 2 =
Temp of water in cup: 25.1 C - 3 = Initial temperature of bomb calorimeter and water in cup
Final temp of the system: 29.2 C - 4 = Final temperature of bomb calorimeter and water in cup; So, heat gained by water, q = m c dT = 50 g x (4.2 J/ g0C) x 4.1 0C = 861 J (approx.). Note: Since, the calculated value of heat absorbed values does not meet the given values (856.9 J), you may get deviations from exact value.
Thus, #3 and #4 are the initial and final temperature of the calorimeter system (calorimeter + water in cup). #1 can’t be the initial temperature of the calorimeter system because, then the final temperature difference would then be above 980C after absorbing the heat released by metal.
#1 must be the temperature of the water bath in which the metal would have been dipped in for some time to for heating up the metal. Assuming this very case to be the problem,
The initial temperature of the metal = 980C
dT = (98 – 29.2)0C = 68.80C
Now, q = m c dT
Or, c = 959.6 J / (33.996 g x 68.80C) = 0.41
Thus, specific heat of the metal = 0.41 J/ g0C
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