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Step 1: Calculate the heat supplied by the electric heater.
The heat supplied by the heater is given by Q=VIt, where V is voltage, I is current, and t is time.
Given: V=1.6V, I=0.1A, t=15min=15×60s=900s.
Qheater=(1.6V)(0.1A)(900s)
Qheater=144J
Step 2: Calculate the heat gained by the ice to melt and then warm up to the final temperature.
The ice first melts at 0∘C (assuming the specific heat capacity of ice is for ice below 0∘C and the latent heat of fusion is at 0∘C). The problem states the ice is added at 2∘C, which is unusual for ice. Assuming it means the ice is at 0∘C and then melts, or it's already water at 2∘C. Given "piece of ice of mass 2kg is added at a temperature of 2∘C", this implies the ice has already melted and is water at 2∘C. However, the problem also provides "latent heat capacity of ice", which suggests melting. Let's assume the ice is at 0∘C and melts, then the resulting water warms up. If the ice is at 2∘C, it's already water. Given the latent heat, it's more likely the ice is at 0∘C and melts. Let's assume the initial temperature of the ice is 0∘C for melting, and then the water formed from ice warms up from 0∘C. The problem states "ice ... at a temperature of 2∘C", which is contradictory. I will assume the ice is at 0∘C and then melts, and the resulting water warms up from 0∘C. If the ice was truly at 2∘C, it would be water, and the latent heat would not apply. Given the latent heat is provided, the most reasonable interpretation is that the ice is at 0∘C and melts.
Heat to melt ice: Qmelt=miceLf
Given: mice=2kg, Lf=336000Jkg−1.
Qmelt=(2kg)(336000Jkg−1)
Qmelt=672000J
Heat to warm the melted ice (now water) from 0∘C to final temperature Tf:
Qwarm,icewater=micecwater(Tf−0\circC)
Given: cwater=4200Jkg−1K−1.
Qwarm,icewater=(2kg)(4200Jkg−1K−1)(Tf−0\circC)
Qwarm,icewater=8400TfJ
Step 3: Calculate the heat lost by the initial water and the copper calorimeter.
Heat lost by initial water: Qwater=mwatercwater(Tinitial,water−Tf)
Given: mwater=40kg, Tinitial,water=30∘C.
Qwater=(40kg)(4200Jkg−1K−1)(30\circC−Tf)
Qwater=168000(30−Tf)J
Heat lost by copper calorimeter: Qcopper=mcopperccopper(Tinitial,copper−Tf)
Given: mcopper=1.5kg, ccopper=400Jkg−1K−1. The initial temperature of the calorimeter is the same as the initial water, 30∘C.
Qcopper=(1.5kg)(400Jkg−1K−1)(30\circC−Tf)
Qcopper=600(30−Tf)J
Step 4: Apply the principle of conservation of energy.
Total heat supplied = Total heat gained.
Heat supplied by heater + Heat lost by initial water + Heat lost by copper = Heat to melt ice + Heat to warm melted ice.
Qheater+Qwater+Qcopper=Qmelt+Qwarm,icewater
144+168000(30−Tf)+600(30−Tf)=672000+8400Tf
144+(168000+600)(30−Tf)=672000+8400Tf
144+168600(30−Tf)=672000+8400Tf
144+5058000−168600Tf=672000+8400Tf
5058144−168600Tf=672000+8400Tf
5058144−672000=8400Tf+168600Tf
4386144=177000Tf
Tf=1770004386144
Tf≈24.78047∘C
The final temperature of the mixture is approximately 24.78∘C.
If we strictly interpret "ice of mass 2kg is added at a temperature of 2∘C", it means it's already water. In that case, there is no melting phase.
Let's re-calculate with this interpretation:
Heat gained by the 2kg of water (from melted ice) from 2∘C to final temperature Tf:
Qwarm,2kgwater=micecwater(Tf−2\circC)
Qwarm,2kgwater=(2kg)(4200Jkg−1K−1)(Tf−2\circC)
Qwarm,2kgwater=8400(Tf−2)J
Applying conservation of energy:
Qheater+Qwater+Qcopper=Qwarm,2kgwater
144+168600(30−Tf)=8400(Tf−2)
144+5058000−168600Tf=8400Tf−16800
5058144−168600Tf=8400Tf−16800
5058144+16800=8400Tf+168600Tf
5074944=177000Tf
Tf=1770005074944
Tf≈28.6719∘C
Given that the latent heat of ice is provided, the first interpretation (ice at 0∘C melts and then warms up) is more likely what the question intended, despite the confusing wording "ice ... at a temperature of 2∘C". It's a common error in problem statements. I will proceed with the first interpretation.
Final Answer based on the assumption that "ice at 2∘C" means ice at 0∘C that melts, and then the resulting water warms up from 0∘C.
Step 1: Calculate heat supplied by the electric heater.
Qheater=VIt=(1.6V)(0.1A)(15×60s)=144J
Step 2: Calculate heat gained by the ice (to melt and warm up).
Heat to melt ice at 0∘C:
Qmelt=miceLf=(2kg)(336000Jkg−1)=672000J
Heat to warm melted ice (water) from 0∘C to Tf:
Qwarm,icewater=micecwater(Tf−0\circC)=(2kg)(4200Jkg−1K−1)(Tf)=8400TfJ
Total heat gained by ice:
Qicetotal=672000+8400Tf
Step 3: Calculate heat lost by the initial water and copper calorimeter.
Heat lost by initial water from 30∘C to Tf:
Qwaterloss=mwatercwater(30\circC−Tf)=(40kg)(4200Jkg−1K−1)(30−Tf)=168000(30−Tf)J
Heat lost by copper calorimeter from 30∘C to Tf:
Qcopperloss=mcopperccopper(30\circC−Tf)=(1.5kg)(400Jkg−1K−1)(30−Tf)=600(30−Tf)J
Total heat lost by calorimeter and initial water:
Qlosstotal=168000(30−Tf)+600(30−Tf)=168600(30−Tf)
Qlosstotal=5058000−168600Tf
Step 4: Apply the principle of conservation of energy (Heat supplied + Heat lost = Heat gained).
Assuming negligible heat loss to surroundings, the heat supplied by the heater plus the heat lost by the warmer components equals the heat gained by the colder components.
Qheater+Qlosstotal=Qicetotal
144+(5058000−168600Tf)=672000+8400Tf
5058144−168600Tf=672000+8400Tf
5058144−672000=8400Tf+168600Tf
4386144=177000Tf
Tf=1770004386144
Tf≈24.78047
Rounding to two decimal places:
Tf≈24.78∘C
The final temperature of the mixture is 24.78\circC.
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