GUIDE QUESTIONS Part 1.

1. Express equation 1 in terms of mass, specific heats, final and initial temperature.

2. Why is it important to immerse the metal in the boiling water for a long time? What happens if the metal was immersed only for a short while? It is important that the metal is immersed completely for a long time so that the boiling water would properly heat the metal. Immersing the metal for a short time would not yield accurate results.

3. Why do you need to wipe off the water from the metals surface before taking the initial temperature? It is needed to wipe of the water from the metal so that the temperature of the water would not affect the temperature of the mixture, which is the metal and the water inside the calorimeter.

4. What is your computed specific heat and percentage of error? Is it acceptable? Why? The computed specific heat is 0.2211 cal/g-C and the percentage error is 1.6976%. I think its acceptable since we got a minimal percentage error and 0.2211 is quite near to the actual specific heat which is 0.2174 cal/g-C

5. What are the sources of errors? What are your recommendations? The possible bases of errors in performing the experiment are: the time the metal is immersed in boiling water. Errors can be minimized if we immerse the metal for a long period of time. It can be minimalize be calculating it near the boiling water to avoid the cold air that also affect the experiment. The temperature of the room is also another source of error since we are performing in the laboratory with well air-conditioned room. Performing the experiment fast and consistent can minimize this. Also, errors may have happened during the recording of the initial temperature of the metals, which was quite hard to record. Another source of error may have been the excess water clinging on the metals surface, which was not wiped off before putting in the calorimeter.

Part 2.

1. Show your derived formula in determining the latent heat of fusion of ice using the law of heat exchange.

2. What is the initial temperature of the ice? What assumptions did you make to determine the initial temperature of ice? The temperature of the ice is assumed to be zero degrees because at that temperature both the solid and liquid state of water is present.

3. Why is it important to wipe off the water from the ices surface before putting it in the calorimeter? It is important to wipe off the water from the ices surface before putting it in the calorimeter because it can affect the initial temperature.

4. Had the mass of ice been greater, how would it affect the result of the experiment and the computed latent heat of fusion? If there will be a different mass of ice, then the latent heat will depend on the mass of the ice. Mass of ice is inversely proportional to the latent heat. If mass of ice is greater than its initial, then the latent heat will decrease.

5. What are the sources of errors and your recommendation? The possible errors are because of the room temperature, since we are performing in the laboratory with air-conditioned room; performing the experiment fast and consistent can minimize it. The mass of ice before and after putting it in the calorimeter is also another source of error. A sudden change in the mass of ice will result to an error. In able to minimize the error, we must wipe off the excess water in the ice before putting it in the calorimeter.

SAMPLE COMPUTATION

Part 1: ALUMINUM

Specific Heat of Aluminum Metal:

Percent Error:

Part 2: Trial 1

Latent Heat of Fusion:

Percent Error:

ANALYSIS

For the first part, water was boiled in the beaker and then metal was immersed in it, one metal at a time. It was important to immerse the metal in the boiling water for a long time because we need to heat up the metal to absorb heat from the boiling water, so that if we transfer the metal in the calorimeter, we can get less error as a result. However, if we immerse the metal for a short period of time, the metal will not absorb much heat that will heat up the calorimeter. The metal should absorb the heat for a long time first before measuring its temperature using a thermometer. The excess water that was on the metal was then wiped off because it can affect the initial temperature. The water in the metal has different a temperature than the metal itself and so that can result in an error for the experiment. Once the initial temperature was measured the heated metal was then placed inside the calorimeter. It was then closed and was mixed using the stick. After a few minutes, the final temperature of the calorimeter was measured. Using the Law of Heat exchange, a derived equation was made to solve for the specific heat of the metal. The aluminium metal being heated by hot boiling water held in a beaker. The temperature was measured and the excess water was wiped off to reduce error and was transferred to the calorimeter. Then the second part of the experiment is about the Latent heat of fusion of ice, the goal is to get the latent heat of fusion of ice. Same in part one, we measure the calorimeter, water and the temperature of water and ice. We put the ice in the calorimeter and melt it. Our initial temperature of ice is 0C. We get the value of mass of ice by subtracting the total mass from the water and calorimeter. And once the ice is being moved into the calorimeter, it is important to wipe off the water from the surface of the ice, because excess water can affect the mass of the ice when measuring it after melting it in the calorimeter. Since we don't need the excess water, we could rather wipe it off to get less error. If there will be a different mass of ice, then the latent heat will depend on the mass of the ice. Mass of ice is inversely proportional to the latent heat. If mass of ice is greater than its initial, then the latent heat will decrease.

CONCLUSIONThermodynamics studies the energy and its interconversions with which all forms of energy follows the first law of thermodynamics since energy in universe is always constant. The internal energy inside a system is the total sum of the potential energy and kinetic energy but usually termed as the sum of heat and work. Work primarily focuses on the expansion or compression of the system. Heat is the energy in motion that causes temperature and phase change in a system. Calorimetry quantitatively measures the heat for both types of changes. Temperature change occurs when there is absorption or discharge of heat without causing the matter to evolve. Temperature is directly proportional to heat. Phase change occurs when there is phase transition at a constant temperature. The process is endothermic when heat is gained and exothermic, otherwise. Specific heat capacity, c, is the energy needed to raise the temperature of one gram of a substance by one degree Celsius or Kelvin. This varies in different materials. Higher specific heat capacity has a higher tendency of losing heat to the surroundings that of lower specific heat capacity. Thus, an obvious change is seen often in materials with high c. On the other hand, latent heat is a constant of proportionality in phase change. This is dissimilar to specific heat capacity since latent heat is independent of temperature change. This constant is divided into fusion and vaporization. Latent heat of fusion is applicable to materials which change their phase from solid to liquid or the other way around while latent heat of vaporization is for materials that change their form from liquid to gas and vice versa. This constant follows a sign convention, positive for heat gain and negative for heat loss. The second experiment verifies the concept of heat and calorimetry though there were some errors found during the experiment such as the temperature of surroundings and on procedures. It would be ideal if an electrical coil inside a constant volume calorimeter with fixed thermometer attached is used instead of a stove to heat the contents of the calorimeter. This will only allow the components inside to act as a system and surrounding unaffected by the environment outside the calorimeter. A closed system would be preferable to minimize errors in taking the precise temperature of the substance inside after mixing or after heating. For the second part of the experiment, the temperature and weight of the ice should be taken in a container where melting is minimized. As much as possible, using bare hands in handling the substances of interest must be avoided since it generates heat that can cause the ice to melt and moisture during weighing.

MAPA INSTITUTE OF TECHNOLOGY

EXPERIMENT 302: HEAT AND CALORIMETRY

NameRABE, Angel Unico C.Group No.4

Program/YearCE-3Seat No.402

Subject/SectionPHY12L B2DateMay 5, 2015

Part 1: Determining the Specific Heat of Metals

Trial 1. Aluminum MetalTrial 2. Brass Metal

Mass of metal, mm31.5 g49.5 g

Mass of calorimeter, mc46.4 g46.4 g

Mass of water, mw168.4 g126.5 g

Initial temperature of metal, tom94 C93 C

Initial temperature of calorimeter, toc27.5 C29 C

Initial temperature of water, tow27.5 C29 C

Final temperature of mixture, tmix30 C31 C

Experimental specific heat of metal, cm0.221 cal/g-C0.0890 cal/g-C

Actual specific heat of metal, cm0.2174 cal/g-C0.0917 cal/g-C

Percentage of error1.6976 %2.9324 %

DATA and OBSERVATIONS

Part 1: Determining the Specific Heat of Metals

Trial 1Trial 2

Mass of calorimeter, mc46.4 g46.4 g

Mass of water, mw234.8 g234.8 g

Mass of mixture, mmix307.3 g291.9 g

Mass of ice, mi26.1 g10.7 g

Initial temperature of ice, toc0 C0 C

Initial temperature of calorimeter, toc26 C23.7 C

Initial temperature of water, tow42.7 C48.5 C

Final temperature of mixture, tmix38 C46.9 C

Experimental Latent heat of fusion, Lf82.0985 cal/g83.5187 cal/g

Actual Latent heat of fusion, Lf80 cal/g80 cal/g

Percentage of error2.5560 %4.2130 %

Approved By:

DateInstructor