Calorimetry and Cooling Curves with Thermometers

Categories: Chemistry

Essay, Pages 3 (690 words)

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Introduction

The aim of this experiment is to determine the boiling and cooling curves of water using different types of thermometers. Additionally, we aim to determine the cooling and melting points of stearic acid and study the cooling curves of paraffin wax.

Equipment

Bunsen burner
Glass rod
Digital thermometer
Alcohol thermometer
300ml beaker
Tripod
Gauze
Boiling tube
Water
Ice cubes
Stopwatch
Stand and clamp
Weighing boat
Spatula
Tong
Test tube holder
Balance

Risk Assessment

Hazard	Risk	Control Measures	Treatment
Hot water	Bunsen burner burns	Wear goggles, lab coat, and gloves	Wash with cold water
Broken glass	Cut and bleeding	Handle the apparatus carefully	Get first aid
Stearic acid	Causes skin and eye irritation	Wear lab coat, gloves, and goggles	Wash with water
Paraffin wax	Cut and bleeding	Wear gloves and lab coat	Wash with water
Bunsen burner	Burn	Wear lab coat and gloves	Wash with cold water

Calorimetry - Water

Method

We began by filling half of a 300ml beaker with ice cubes and a small amount of tap water.

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After stirring the mixture with a glass rod, we allowed it to cool for 2 minutes.

Next, we placed thermometers into the beaker and left them to record the results for each thermometer in freezing water. Subsequently, we placed the beaker on a Bunsen burner to boil the water and recorded the temperature of the boiling water.

State of Water	Alcohol Thermometer (°C)	Digital Thermometer (°C)	Actual Water Temperature (°C)
Freezing	6	2	0
Boiling	100.1	100.2	100

Stearic Acid

Method

First Attempt: We filled a large beaker with water and placed it on a Bunsen burner to boil.

Then, we added three spatulas of stearic acid into a test tube and carefully placed it in the boiling water bath using tongs. Once the stearic acid melted, we moved the test tube to a test tube holder and immediately began recording the temperature using an alcohol thermometer every 60 seconds until the liquid solidified and cooled down to 30°C.

Problem: The alcohol thermometer eventually stopped at 54°C, and there wasn't enough stearic acid.

Solutions: We decided to use a boiling tube, a digital thermometer, and a balance for the second attempt.

Second Attempt

We filled a large beaker with water and placed it on a Bunsen burner to boil. Using a weighing boat and a balance, we measured exactly 3.00g of stearic acid and added it to a boiling tube. The boiling tube was then carefully placed in the boiling water bath using tongs. Once the stearic acid melted, we moved the boiling tube to a test tube holder and immediately began recording the temperature using a digital thermometer and a stopwatch every 60 seconds until the liquid solidified and cooled down to 30°C.

Time (s)	Temperature (°C)
60	68
120	64
180	58
240	57
300	54
360	53
420	52
480	52
540	50
600	50
660	48
720	47
780	44
840	42
900	40
960	36
1020	34
1080	30

Paraffin Wax

Method

We placed 3.00g of paraffin wax in a boiling tube, then used tongs to carefully place the boiling tube in a water bath. We immediately began recording the temperature once the paraffin had melted and continued recording the temperature every 60 seconds until the liquid solidified and cooled down to 30°C.

Time (s)	Temperature (°C)
60	71
120	67
180	60
240	54
300	51
360	50
420	49
480	48
540	47
600	45
660	42
720	39
780	36
840	35
900	33
960	31
1020	30

Discussion

The cooling curves of stearic acid and paraffin wax show a typical trend. As the substances were heated, their temperatures increased. During cooling, their temperatures decreased steadily. For stearic acid, we observed a consistent decline in temperature from 68°C to 30°C over 1020 seconds. Paraffin wax showed a similar trend, with temperatures decreasing from 71°C to 30°C over 1020 seconds.

The digital thermometer proved more accurate and reliable than the alcohol thermometer, as the latter stopped at 54°C during the first stearic acid trial. This suggests that the digital thermometer is better suited for experiments requiring precise temperature measurements in confined spaces.

Conclusion

In conclusion, this experiment allowed us to determine the boiling and cooling curves of water using different thermometers. We successfully determined the cooling and melting points of stearic acid and studied the cooling curves of paraffin wax. The results demonstrated the importance of using the right equipment for accurate measurements. The digital thermometer proved to be a more reliable choice when compared to the alcohol thermometer. Overall, the experiment provided valuable insights into the behavior of substances during heating and cooling processes.