1. Two bars of identical mass are at 27 °C. One is made from glass and the other
ID: 1506205 • Letter: 1
Question
1. Two bars of identical mass are at 27 °C. One is made from glass and the other from another substance. The specific heat capacity of glass is 840 J/(kg · C°). When identical amounts of heat are supplied to each, the glass bar reaches a temperature of 98 °C, while the other bar reaches 279.0 °C. What is the specific heat capacity of the other substance?
2.Objects A and B have the same mass of 4.7 kg and are at their melting points. They melt when 4.5 × 104 J of heat is added to A and when 10 × 104 J is added to B. (a), (b) Determine the latent heat of fusion for the substance from which each object is made. (c) Find the heat required to melt object A when its mass is 9.4 kg.
3.Occasionally, huge icebergs are found floating on the ocean's currents. Suppose one such iceberg is 139 km long, 27.8 km wide, and 203 m thick. (a) How much heat in joules would be required to melt this iceberg (assumed to be at 0 °C) into liquid water at 0 °C? The density of ice is 917 kg/m3. (b) The annual energy consumption by the United States in 1994 was 9.3 x 1019 J. If this energy were delivered to the iceberg every year, how many years would it take before the ice melted?
4 x 105 100 °C .01 x105 Pa 3 x 10 5 0.53 x 105 Pa 2 x 10% 83 C 1.01 x 105 -- 0.53x105 0 50 0 50 83 100 150 Temperature, CExplanation / Answer
Here ,
1) T1 = 27 degree C
specific heat of glas , Sg = 840 J/(kg.degree C)
T2 = 98 degree C
T3 = 279 degree
heat gain by glass = heat gain by unknown sustance
m * Sg * (T2 - T1) = m * S * (T3 - T1)
840 * (98 - 27) = S * (279 - 27)
S = 236.7 J/(Kg.degree C)
the specific heat capacity of the other substance is 236.7 J/(Kg.degree C)
2)
m = 4.7 Kg
qA = 4.5 *10^4 J
qB = 10 *10^4 J
a) let the latent heat of object A is lA
qA = m * lA
4.5 *10^4 = 4.6 * lA
lA = 9782 J/(kg)
the latent heat of A is 9782 J/(kg)
b) for the latent heat of object B is lB
qB = m * lB
4.5 *10^4 = 4.6 * lB
lB = 21739 J/(kg)
the latent heat of B is 21739 J/(kg)
c) for the mass of A
mA = 9.4 Kg
heat required for mass A = mA * lA
heat required for mass A = 9.4 * 9782 J
heat required for mass A = 91951 J
the heat required for mass A is 91951 J
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