**Calorimetry Experiment**

*Keywords: calorimeter, Ammonium Chloride, Calcium Chloride, heat,*

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**ABSTRACT: **The Calorimetry Experiment was carried out to investigate the process of obtaining the calorimeter constant and the effects of a substance to the temperature of a solution. For the first part of the experiment, the temperatures for hot and cold water were recorded and inputted in the specific heat formula and the calorimetry constant formula. For the second part, 2g of ammonium chloride was placed in a calorimeter with water. The researchers recorded the initial and final temperatures and obtained the enthalpy of the solution, this was repeated with calcium chloride. Several scientific concepts were utilized in this research, namely calorimetry, specific heat, and enthalpy of a solution.

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1

**INTRODUCTION**

The objective of the study is to find out how to obtain the calorimeter constant of a system and the effects of a substance to the temperature of a solution. The first research question this experiment aims to answer is “How can the calorimeter constant be obtained?” The researchers have developed a hypothesis stating that if the temperatures of cold and hot water are measured, then the calorimeter constant can be obtained. To understand this concept further, calorimeter constant should be defined. the calorimeter constant is the quantity of heat energy needed to increase the temperature of the calorimeter by 1 degree Celsius (Deziel, 2018). The second research question is “What is the effect of ammonium chloride to the temperature of a solution?” Its hypothesis states that if ammonium chloride is added into a solution, then the temperature of the solution will decrease. Ammonium chloride has many uses, specifically, it is used in ski slopes to maintain hardened snow (Khadka, 2018). The last research question is “What is the effect of calcium chloride to the temperature of a solution?” The respective hypothesis is that if calcium chloride is added into a solution, then the temperature of the solution will increase. Calcium chloride is often used or road deicing, due to its properties that decrease the melting point of ice (Deziel, 2019).

**METHODOLOGY**

**Materials.**

**Substances – **20mL cold distilled water, 20mL hot distilled water, 2g Ammonium Chloride, 2g Calcium Chloride

**Equipment – **Calorimeter, Temperature sensor (oC), 1pc. 500-mL beaker, 1 pc. 50-mL syringe, 50-mL graduated cylinder

**Procedure.**

The first part of this experiment aims to calculate for the calorimeter constant using only water, a temperature sensor, and a calorimeter. To do this, the necessary temperatures and volumes need to be measured. Afterwards, the hot and cold water will be mixed and then the temperature will also be measured. The variables are then going to be inputted into an equation (Fig. 2). The quantities will be substituted with their corresponding values and the heat for the cold water and hot water can be calculated. When these values are obtained, another equation (Fig. 2) will be utilized to compute for the calorimeter constant.

The second part of this experiment aims to determine if the addition of ammonium chloride decreases the temperature of water. By measuring the initial temperature of the water without the substance, as well as the temperature of the water after the addition of the substance, the volume of water, the mass of the substance, and the molar mass of the substance, the values can be placed into anequation (Fig 3).This equation will be utilized to compute for the heat of the solution which will give insight into whether the temperature increases or decreases.

The third and final part of this experiment aims to determine if the addition of calcium chloride will increase the temperature of the solution. The method for this is similar to the second part as it utilizes the same equation (Fig. 4) and the same process. Similarly, an increase or decrease in temperature can be inferred after calculating the heat of the solution.

**RESULTS AND DISCUSSION**

The first part of this experiment was tested through the use of a calorimeter and a temperature sensor. The cold water and hot water were first tested for their temperature. This yielded 30.6oC and 50oC for the cold water and hot water, respectively. This was then mixed together and the temperature of this mixture was measured to be 36.2oC. Using these values, the heat of the cold water and heat of the hot water were obtained. This was computed (Fig. 2) to be 468.61 J and -1079.47 J, respectively. These values are further used in another equation, along with the change in temperature, in order to calculate for the calorimeter constant. When calculated, the value is 109.08 J/oC, thus the calorimeter constant can be computed for with the use of water, a temperature sensor, and a calorimeter.

The second part of this experiment involved adding 2g of ammonium chloride to 20mL of water. The initial temperature of the water was measured to be 30.8oC. After the addition of the substance, the temperature measured out to be 25.4oC. This observation shows a decrease in temperature, but this claim can further be proved by computing for the enthalpy of the solution. This was done by inputting the mass, the specific heat constant, the change in temperature, and molar mass into an equation (Fig. 3) and then solving for the required quantity. When all values are substituted, the enthalpy is computed to be -12085.54 J/mol. The calculated value is negative which denotes a loss in heat. Thus, the temperature decreases.

The third and final part of this experiment involved adding 2g of calcium chloride to 20mL of water.The initial temperature of the water without the added substance was measured to be 29.5oC. When the water and the substance were mixed into a solution, the resulting temperature increased to 37.2oC. The claim that there is an increase in temperature was further proved by computing for the enthalpy of the solution. Similar to the previous part, the necessary variables were substituted into the corresponding equation (Fig. 4)and the enthalpy was computed. This value was calculated to be 35755.49 J/mol. As the quantity is positive, it can be inferred that heat was absorbed, thus denoting that the temperature was increased.

**CONCLUSIONS AND RECOMMENDATIONS**

After analyzing the data, the researcher accepts all three hypotheses. It is correct to conclude that the use of water at different temperatures and the specific heat formula will yield the calorimeter constant of a system. It is also correct to conclude that ammonium chloride and calcium chloride change the temperature of a solution when added, each decrease and increase temperature respectively.

The results may be affected by the inaccuracies in the execution of the experiment. The researchers did not strictly follow the timer when waiting 2-3 minutes after collecting the cold and hot water. This may have affected the temperatures that were recorded and processed.

**REFERENCES**

[1] Deziel, C. (2019, March 2). How to Calculate Calorimeter Constant. Retrieved December 11, 2019, from https://sciencing.com/how-to-calculate-calorimeter-constant-13710547.html.

[2] Deziel, C. (2019, March 18). Common Uses of Calcium Chloride. Retrieved December 11, 2019, from https://www.hunker.com/12203530/common-uses-of-calcium-chloride.

[3]Khadka, S. (2019, March 2). The Acid & Base Components of Ammonium Chloride. Retrieved December 11, 2019, from https://sciencing.com/acid-base-components-ammonium-chloride-8352438.html.

**APPENDIX**