Calorimetry Experiment
Lab Report
Introduction
Calorimetry is a process of measuring the amount of heat involved in a chemical reaction or other process. In this experiment, I used thermometer to see if the chemicals is gaining or losing heat energy.
Objectives
To find out the heat released or changed in a reaction.
Materials
Stopwatch 2 Thermometers 2 Styrofoam cups 0.5 , 1 , 2 moles of HCl 0.5 , 1 , 2 moles of NaOH Beakers Gloves and lab coat
Scissors
Procedure
1. Prepare the materials and use lab coat and gloves for protection
2. Draw tables to record the data of the initial temperature and the temperature for every 30 seconds (until four minutes) of each chemicals and the combined chemicals.
3. Prepare 2 Styrofoam cups. Cut a little bit of one Styrofoam cup and place it on the top of the other cup, so it will looks like a shaker. Make sure you can still open it so you can pour the chemicals later.
4. Make a hole on the top of the cup to put the thermometer.
5. Take 100 ml of a Sodium Hydroxide and Hydrochloric Acid with concentration of 0.5M. Put it in two separated beakers and measure the temperature of both mixtures. Write the data.
6. Pour NaOH and HCl together to the Styrofoam cup. Quickly and carefully close the Styrofoam cup with the other Styrofoam and put the thermometer in. Count the initial temperature.
7. Stir the combined chemicals slowly with the thermometer (in case you don’t have a stirrer) and record the temperature changes for 240 seconds.
8. After 240 seconds, pour the combined chemicals out of the Styrofoam.
9. Repeat step 5-12 for 1M and 2M, but make sure you’ve washed the Styrofoam before repeating the steps.
Hypothesis
The heat will increase at first, but it will decrease after some times. This process can be categorized as Exothermic reaction, because this releases energy during the process.
Data & Result:
Initial temperature of HCl and NaOH
Temperature of combined chemicals during reaction
Temperature in graph Hydrocloric acid (HCl) Molarity 0.5 1 2 Temperature 21 C° 22.5 C° 22.9 C° Sodium Hydroxide Molarity 0.5 1 2 Temperature 15. C° 15.9 C° 27 C° Time (second) 0.5M 1M 2M 0 28 C° 30 C° 35 C° 30 29 C° 32 C° 39 C° 60 29 C° 32 C° 39 C° 90 29 C° 32 C° 39 C° 120 28.5 C° 32 C° 38.5 C° 150 28.5 C° 32 C° 38.5 C° 180 28.25 C° 31.5 C° 38 C° 210 28.25 C° 31.5 C° 38 C° 240 28 C° 31 C° 37 C° 0 5 10 15 20 25 30 35 40 45 0 30 60 90 120 150 180 210 240 Temp er at u re (C el ciu s) Time (second)
Sodium Hydroxide + Hydrochloric
Acid
0.5 1 2
Temperature of 0.5M of NaOH + HCl Temperature of 1M of NaOH + HCl 27.8 28 28.2 28.4 28.6 28.8 29 29.2 0 50 100 150 200 250
0.5M NaOH + HCl
Y-Value 1 29.5 30 30.5 31 31.5 32 32.5 0 2 4 6 8 101M NaOH + HCl
Series134 35 36 37 38 39 40 0 2 4 6 8 10 temp er at u re Time
2M NaOH + HCl
Temperature of 2M of NaOH + HClCalculation
Formula: Q= mc (Tf – Ti) Tf = Final Temperature Ti = Initial temperature C= 4180 J/ g celcius Q= Heat M= 10g 0.5M = 29.2-28 = 1.2oC c = 4180 KJ/goC m = 200g Q = 200 x 4.184 x 1.2 = 1004.16 KJ 1M = 32.25-30 = 2oC c = 4.184 KJ/goC m = 200g Q = 200 x 4.184 x 2.25 = 1882.8 KJ 2M = 39.2-35 = 4.2oC c = 4.184 KJ/gOC m = 200g Q = 200 x 4.184 x 4.2 = 3514.56 KJQuestions and answers
1. Why is it important that these reactions be run in a styrofoam cup (as opposed to a beaker)?
Styrofoam cup is a very good insulator. The loss of energy to the experiment’s surrounding will be less in the styrofoam cup compare to the beaker. In Styrofoam, the molecules are intertwined and the trap air inside the Styrofoam. You can squeeze the cup and force some of the air out. As the water molecules collide with the polystyrene and air, a variety of types of collisions occur.
The kinetic energy does not pass from molecule to molecule in an orderly pattern. This means much more time is required for the temperature of the outside of the cup to be the same as the temperature of the water. Because of this, we can conclude that Styrofoam is a better insulator than a breaker. 2. There is a flaw in the setup of this experiment. Somewhere, heat was
absorbed by an object that was not measured by our tests. Identify the object that absorbed the remaining heat energy.
The heat is absorbed by the water and the cup.
Practical Calculations
Formula: Q= mc (Tf – Ti)
Tf = Final Temperature, Ti = Initial temperature, C= 4.180 J/ g celcius, Q= Heat, M= 200g
0.5 mole Q = 200 x 4.184 x 1.2 = 1004.16/1000 = 1.00416KJ 1 mole Q = 200 x 4.184 x 2.2 = 1882.8/1000 = 1.8828 KJ 2 moles Q = 200 x 4.184 x 4.2= 3514.56/1000 = 3.51456 KJ
Theory Calculations
In theory, the answer should be -58KJ/mol. And here, I will calculate the error of my calculation from my experiment
0.5 mole 200ml = 0.2L mol: 0.5 x 0.2 = 0.1mol 1.00416/0.1 = 10.0416 (-58+10.0416) x 100 = 82.68% 58 1 mole 200ml = 0.2L mol: 1 x 0.2 = 0.2mol 1.8828 /0.2 = 9.414 ((-58+9.414) /58) x 100 = 83.76%
2 moles 200ml = 0.2L mol: 2 x 0.2 = 0.4mol 3.51456 /0.4 = 8.7864 ((-58+8.7864)/58) x 100 = 84.85%
Analysis
In this experiment, we tested the the change of temperature of NaOH, HCl, and both of the chemicals combined.
The first experiment was using 0.5M of NaOH and HCl. At first, the temperature increase from 28 C° to 29 C° and it stays constant for about 90 seconds. It starts to decrease to 28 C° after about a minute.
The same situation also applies to the second and third experiment. For the second experiment, I used 1M of NaOH and HCl and 2M for the third. The temperature for the second experiment increase from 30 C° to 32 C° and stay constant for about 2 minutes. The temperature for the third experiment increases from 35 C° to 39 C°. After about a minute, the temperature of the chemicals of the 2nd and 3rd experiment starts to decrease.
From the data that i took, we can see that the temperature is based on the amount of mole. If the the amount of mole in the solution is high, then the temperature will also be higher. The temperature increasing and decreasing after some moments, and stay constant on some points.
Discussion Theory
On my opinion, it’s impossible to get the accurate result of this experiment. While doing this experiment, some heat will always escape from the cup, and it will affect the calculation. The water we’re using & the cup also absorb the heat too, and the heat will also escape if we’ve poured the chemicals but didn’t close the cup quickly. Even though only small amount of heat escaped, it will still affect the calculation.
Error Analysis
Error might occur when some heat escape from the cup. Some of the heat were absorbed by the water & the cup, and also escape when we didn’t close the cup correctly. Me and my friends carelessly left the hole that we made to put the thermometer untight and opened, causing the heat to escape. This experimental error was also most likely caused by incorrect measure of the chemicals. The different between the weights of the chemicals or mixtures resulted in the differences between heat capacities after all the calculations were done.
Conclusion
The conclusion of this experiment is; materials really affects the experiment. On my experiment, i did some mistakes like; didn’t close the cup properly and left a small hole (on the top of the cup where we put the thermometer) and let some heat released.
The use of styrofoam also affect the experiment. If we use other material like beaker, which takes less energy to lose heat (lets the heat escape easier). The heat on the glass beaker will flow from the water, through the glass, and to our hand. Using paper cup is also not recommended, because it conducts heat. It will affect the calculation and will give us different value.
To have the best accurate result, we have to make sure that all the materials are in the best condition. Make sure we have sealed the hole accurately so there’s no way heat will escape. Just in case, cover the styrofoam cup with another cup for safe in case it’s leaking or spilled.
