MAPUA INSTITUTE OF TECHNOLOGY
Department of Physics
E302: HEAT AND CALORIMETRY
BUNDALIAN, Patrick John Edbert G.
[email protected]/2010140216/CPE-3
PHY12L-A1 Group 3
August 10, 2015
SCORE
Signed Data Sheet
(5) = ____
Objective
(5) = ____
Materials & Method
(10) = ____ Observations and Results (20) = ____ Discussion & Conclusion (20) = ____ Acknowledgment & References (10) = ____ Performance (30) = ____ TOTAL (100) = ____
1 |
P a g e
E302: HEAT AND CALORIMETRY BUNDALIAN, Patrick John Edbert G.
OBJECTIVE
The experiment was carried out with the intention to determine the specific heat of a metal and the latent heat of fusion of an ice. In addition, this experiment was conducted to provide feasible explanation to the theory governing heat and calorimetry as defined in the equation:
𝑄 = 𝑚𝑐∆𝑡
It is no secret that when two bodies, which are initially at different temperatures, are placed in close contact, in time the temperatures of the bodies will reach a point of equilibrium. Provided no heat is either lost or gained at the setting, the quantity of heat lost by the hot body shall be equal to the quantity gained by the cold body:
𝑄𝐿𝑂𝑆𝑆= 𝑄𝐺𝐴𝐼𝑁𝐸𝐷
It is assumed that the transfer of heat between the thermometer and the system is miniscule so there is no surprise that it can be neglected.
If the net heat exchange with the surrounding can be controlled to small quantities, then the heat lost by the metal sample shall roughly be the same as the heat gained by the water and the calorimeter cup!
MATERIALS AND METHODS
The following are the materials used in the whole experiment (from left to right): (a) Digital weighing scale, (b) Calorimeter, (c) Aluminum and Brass, (d) Beaker, (e) Thermometers, and (f) Portable stove. (Please see figure 1)
For the first part, tap water was boiled for the purpose of obtaining the specific heat of both aluminum and brass. Please note that due to the laboratory’s air-conditioning, the stove’s heat was set to max. (Please see figure 2)
Before submerging the metals in the beaker with boiling water (Please see figure 3), the mass of both metals mm using the
digital weighing scale was obtained so as the mass of the calorimeter mc and the
mass of the calorimeter with tap water. To obtain the mass of the tap water mw
contained inside the calorimeter, the obtained mass of the calorimeter with water was simply subtracted by the mass of calorimeter mc.
Figure 1. The materials used in the experiment.
Figure 2. Tap water was boiled and at the same time, tap water’s initial temperature was obtained.
Figure 3. Brass was heated in the boiling water. The calorimeter was placed near to preserve heat.
2 |
P a g e
Aluminum was submerged in the boiling water for roughly 10 minutes, this was done to make sure that the metal will conduct sufficient heat. The calorimeter was placed near the stove; the principle behind that was to lessen the time to transfer the metal into the calorimeter ensuring that the heat conducted by the metal was preserved to near 100oC. This
method was also done obtaining the specific heat of brass.
The aluminum was transferred inside the calorimeter with tap water. Hot water is denser than cold water hence to hasten the process of heat exchange, stirrer was used to mix the hot (ensued by the heat coming from the metal) and cold water inside the calorimeter by moving it up (supplying hot water into the surface) and down (supplying cold water into the bottom). (Please see figure 4) The heat of the mixture tmix was then recorded after the
observing that the thermometer’s indicator ceased from increasing. That simply meant that the system’s temperature reached equilibrium and heat exchange was completed. The same procedure was done to brass.
For the second part of the experiment, hot water was poured into the calorimeter for the purpose of obtaining the latent heat of fusion of ice. The initial temperature of the hot water was recorded. The mass of the hot water was obtained by subtracting the mass of the calorimeter to the mass of the calorimeter with hot water.
After, ice was poured into the calorimeter. (Please see figure 5)
The thermometer’s temperature indicator abrupltly decreased after the stirrer was used to hasten the heat exchange. (Please see figure 6)
When the ice melted completely so the equilibrium temperature was achieved, it was the time to obtain the mass of the ice. (Please see figure 7) First, the mass of the calorimeter with melted ice was recorded; after, the mass of the calorimeter with hot water was subtracted to the mass of the calorimeter with melted ice.
Thermometer
Metal
Tap water
Stirrer
Calorimeter Figure 4. Stirrer was used to hasten the heat exchange ensued by the metal.
Thermometer
Ice
Calorimeter Stirrer
Tap water
Figure 6. Stirrer was used to hasten the heat exchange ensued by the ice.
Figure 5. Ice and hot water were poured inside the calorimeter.
Figure 7. Ice melted; equilibrium of temperature achieved. Time to determine the mass of ice.
3 |
P a g e
OBSERVATIONS AND RESULTS
Due to the cool temperature of the setting, the experimental value of the results, involving heat, did not bode well with the supposed results we should have obtained as seen in this experiment – the percentage of error became inevitably high.
To determine the specific heat of the two metals in the first experiment, this formula was used:
𝑄𝑚𝑒𝑡𝑎𝑙 = 𝑚𝑚𝑐𝑚∆𝑡𝑚 𝑄𝑚𝑒𝑡𝑎𝑙= 𝑚𝑚𝑐𝑤∆𝑡𝑤+ 𝑚𝑐𝑐𝑐∆𝑡𝑐
Here is the computation to come up with a value for the specific heat of aluminum as reflected in the table (Please see table 1):
𝑄𝐴𝑙=
−[134.8(1)(33 − 29)+ 46.9(0.217)(33 − 29)]
33.4(33 − 29)
𝑄𝐴𝑙= −0.3694 𝑐𝑎𝑙
𝑔.𝑜𝐶
To determine the latent heat of fusion of ice in the second experiment, this formula was used:
𝑄𝑙𝑜𝑠𝑠= 𝑚𝑐𝑐𝑐∆𝑡 + 𝑚𝑤𝑐𝑤∆𝑡 𝑄𝑔𝑎𝑖𝑛𝑒𝑑= 𝑚𝑖𝑐𝑒𝐿𝐹+ 𝑚𝑖𝑐𝑒𝑐𝑤(𝑡𝑚𝑖𝑥− 0) Here is the computation to come up with a value for the latent heat of fusion of ice as reflected in the table (Please see table 2):
𝑄𝑔𝑎𝑖𝑛𝑒𝑑= |46.9(0.217)(47−73)+198.8(47−73)|−35.8(1)(47−0)33.8 𝑄𝑔𝑎𝑖𝑛𝑒𝑑= 104.553 𝑐𝑎𝑙𝑔
Table 2. LH of Fusion of Ice Trial 1 Trial 2 Mass of calorimeter, mc 46.9g 46.9g
Mass of water, mw 198.5g 186.2g
Mass of mixture, mmix 234.3g 232g
mass of ice, mi 35.8 45.8
Initial temperature of ice, toi 0°C 0°C
Initial temp. of calorimeter, toc
73°C 80°C
Initial temp. of water, tow 73°C 80°C
Final temp. of mixture, tmix 47°C 46°C
LH of fusion, LF 104.553
cal/g
99.782cal/g
Actual Specific LH of fusion, LF
80 cal/g 80 cal/g
Percentage of error 30.692 %
24.728%
DISCUSSION & CONCLUSION
This experiment is the perfect example why having a controlled room temperature when conducting heat transfer experiments is vital because the core principle of each trials boiled down to how the surrounding’s
Table 1. Det. SH of Metal Al Brass Mass of metal , mm 33.4g 49.96g
Mass of calorimeter, mc 46.9g 46.9g
Mass of water, mw 134.8g 142.8g
Initial temp. of metal, tom 80°C 73°C
Initial temp. of calorimeter, toc
29°C 29°C
Initial temp. of water, tow 29°C 29°C
Final temp. of mixture, tmix 33°C 31°C
SH of metal, cm 0.3694ca l/g-C° 0.1469ca l/g-C° Act. SH of metal, cm 0.2174 cal/g-C° 0.0917 cal/g-C° Percentage of error 69.925% 60.161%
4 |
P a g e
temperature is a prime catalyst to a body’s temperature. This can better be illustrated by picturing and analyzing the effect of submerging ice, which is solid, in the calorimeter with hot water – almost instantly, the ice melted into liquid form because the ice absorbed the heat from the hot water. The same goes when the heated metal was submerged in the calorimeter with tap water – this time however, the metal cooled because the tap water, which is cooler than the metal, absorbed its heat. This principle of heat transfer is called conduction.
As observed in both part 1 and part 2 of the experiment, the stirrer was pulled up and down to hasten heat exchange. The idea behind that, in my opinion, is to introduce heat from the bottom of the calorimeter to the surface of the calorimeter and to introduce coldness from the surface of the calorimeter to the bottom of the calorimeter respectively. The principle behind that is called convection as it talks about how the hot part of a liquid, being dense, will be forced at the bottom and the cold part, being less dense, surfaces.
ACKNOWLEDGEMENT & REFERENCE
As usual, this paper is not fully my brainchild. So I give full credence to the people and written materials who and which helped me accomplish this work with only few notable encountered difficulties – typing the entirety of this work being the first.
I won’t be a hypocrite not to acknowledge my groupmates’ candid posts in our group. These innocent posts shedded light on how I will tackle the bumpy parts of this experiment without having to suffer it first before I get results. I acknowledge Ma’am Novida’s lecture, yet again, especially the part where she talked about convection
and how scooping the bottom part of the coffee and pouring it back into the cup looks more posh but at the same time consumes less energy while ensuing same effects as stirring the beverage while blowing it in the attempt to cool it fast. I acknowledge Sir De Leon’s meticulous introduction and instructions; I really savor the idea that eventually he gives out tips on how to make the experimentation process easier, practical, and most importantly logical saving yourself from giving common sense a bad name. And last, I acknowledge the unubuiquitous feeling of guidance from above – you just know you’re favored.
Here the links of my trusted pages: [1]http://www.asminternational.org/docu ments/asmreadyreference/ [2]http://www.aplusphysics.com/courses/ honors/calorimetry.html [3]http://www.owlnet.rice.edu/~msci301/ calorimetry.pdf [4]
