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Here are the solutions for the problems:
12. Determine the specific heat capacity of the metal.
Step 1: Identify the given values and the principle of heat exchange.
The heat lost by the metal is equal to the heat gained by the oil.
For the metal:
Mass, mm=40 kg
Initial temperature, Tm,i=600∘C
Final temperature, Tm,f=40∘C
Specific heat capacity, cm=?
For the oil:
Mass, mo=300 kg
Initial temperature, To,i=25∘C
Final temperature, To,f=40∘C
Specific heat capacity, co=2100J/kg⋅∘C
The principle is Qlost,metal=Qgained,oil.
The formula for heat transfer is Q=mcΔT.
Step 2: Calculate the temperature changes for both the metal and the oil.
For the metal:
ΔTm=Tm,i−Tm,f=600\circC−40\circC=560\circC
For the oil:
ΔTo=To,f−To,i=40\circC−25\circC=15\circC
Step 3: Set up the heat balance equation and solve for cm.
mmcmΔTm=mocoΔTo
(40kg)⋅cm⋅(560\circC)=(300kg)⋅(2100J/kg⋅\circC)⋅(15\circC)
22400⋅cm=9450000
cm=224009450000
cm=421.875J/kg⋅\circC
The specific heat capacity of the metal is 421.875J/kg⋅\circC.
13. How much water is frozen?
Step 1: Identify the given values and the principle of heat exchange.
The heat gained by the ice to warm up to 0∘C is equal to the heat lost by the water as it freezes.
For the ice:
Mass, mice=100g=0.1 kg
Initial temperature, Tice,i=−20∘C
Final temperature, Tice,f=0∘C
Specific heat capacity of ice, cice=2302J/kg⋅∘C
For the water:
Initial temperature, Twater,i=0∘C
Latent heat of fusion, Lf=3.35×105 J/kg
Mass of water frozen, mfrozen=?
The principle is Qgained,ice=Qlost,water.
Step 2: Calculate the heat gained by the ice to warm from −20∘C to 0∘C.
Qgained,ice=miceciceΔTice
ΔTice=Tice,f−Tice,i=0\circC−(−20\circC)=20\circC
Qgained,ice=(0.1kg)⋅(2302J/kg⋅\circC)⋅(20\circC)
Qgained,ice=4604J
Step 3: Calculate the mass of water frozen using the heat gained by the ice.
The heat lost by the water as it freezes is given by Qlost,water=mfrozenLf.
Since Qgained,ice=Qlost,water:
4604J=mfrozen⋅(3.35×105J/kg)
mfrozen=3.35×105J/kg4604J
mfrozen≈0.013743kg
To express this in grams:
mfrozen≈0.013743kg×1000g/kg≈13.743g
The mass of water frozen is approximately 0.0137kg.
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