Boiling point Determination

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School

Northeastern University *

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Course

1211

Subject

Chemistry

Date

Apr 3, 2024

Type

pdf

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Uploaded by GeneralElectronGull33

Introduction : The goal of this experiment is to determine an unknown liquid (886) based on the physical property of the boiling point. To determine which alcohol was being tested accurately, we utilized prior knowledge on the three types of alcohols and their boiling points. This experiment deals with boiling point which is situated on the strength of the bonds found within a substance. If there are more bonds/ stronger intermolecular forces(IMFs) the boiling point of the substance is going to be higher as it is harder to break apart the bonds. Chemical Responsibility : To assure the safety of everyone in the lab, there were a couple steps taken. Each person received a lab coat, disposable, and safety goggles. Prior to the lab we were informed to close toed shoes and pants to avoid chemical spilling on your skin. The safety goggles ensured that our eyes were protected all times from the substance used in the experiment. Once the experiment ended all the unknown chemicals were properly disposed of in the bottle labeled WASTE EXPERIMENT 1 BOILING POINT UNKNOWNS. The bunsen burners were turned off when not in use and were tended at all times to prevent any fire. Report Sheet : I. Thermometer Calibration Barometric Pressure: 765mmHg Correct boiling point of water: 100.2 ℃ Thermometer reading in ice water bath: 1 ℃ Thermometer reading in boiling water bath: 95 ℃ Thermometer errors: at 0 ℃ = +1 ℃ at 100 ℃ = -5.2 ℃ Thermometer corrections: at 0 ℃ = -1 ℃ at 100 ℃ = +5.2 ℃ II. Unknown Determination Code number of unknown: 886 Observed boiling point Trail I: 72 ℃ Trail II: 72 ℃ Sample Calculations : Water - Boiling point error: 95 ℃ - 100.2 ℃ = -5.2 ℃ - Freezing point error: 1 ℃ - 0 ℃ = 1 ℃ - Boiling point corrections: 100.2 ℃ - 95 ℃ = 5.2 ℃ - Freezing point corrections: 0 ℃ - 1 ℃ = 1 ℃ Discussion of Results : The data we collected for the freezing point of water, boiling point of water, and boiling point of an unknown substance (#886). The absolute freezing point of water for the experiment is 0.0 ℃ but the thermometer reading for slush ice bath when tested was 1 ℃ .

This implies that there is an error of +1 ℃ , and the correction would be -1 ℃ . This means that the thermometer reading is 1 ℃ off from the correct freezing point of water. The absolute boiling point of water in this experiment was 100.2 ℃ but the thermometer reading for the boiling point of water was 95 ℃ . This implies there’s an error of -5.2 ℃ , so the correction would be +5.2 ℃ . This indicates that the thermometer reading is 5.2 ℃ off from the correct boiling point of water. The boiling point of unknown 886 for the first trial was 72 ℃ . The boiling point of unknown 886 for the second trial was also 72 ℃ . The corrected boiling point for both trail 1 and trail 2 was 78 ℃ . The average for the observed boiling point was 72 ℃ and the average corrected boiling point 78 ℃ . There was an error of -6 ℃ because the correct boiling point is 78 ℃ and the observed temperature is 72 ℃ . Something that might have gone wrong throughout the duration of the experiment was the thermometer reading had an error of 5.2 ℃ for boiling point of water and an error of 1 ℃ for the freezing point of water. Another error during the experiment was not adding a second capillary tube and the unknown substance evaporating, but it was fixed through another trail. Post Lab Questions : 1.) Why is it necessary to calibrate your thermometer ? It is necessary to calibrate a thermometer to assure accurate reading, as the accuracy of a thermometer can drift over time. 2.) Why is it necessary to know the atmospheric pressure in order to calibrate your thermometer? It is necessary to know the atmospheric pressure in order to calibrate the thermometer because atmospheric pressure impacts the boiling point directly.

3.) Why do you need to make an ice water slush mixture (instead of only ice) in order to calibrate your thermometer at 0 ℃ ? You need ice water slush because you want a constant repeatable temperature to calibrate your thermometer. 4.) What functions does the inverted capillary tube perform? A liquid’s boiling poin can be determined using the capillary method. As the temperature increases, the air in the capillary escapes and is replaced by the vapor of the liquid. 5.) A student celebrated his/her thermometer and obtained a reading of -2.0 ℃ in an ice water slush bath. What is the error (including the sign) in the thermometer reading? The error is -2.0 ℃ in the thermometer reading. 6.) Rubbing alcohol boils at 82.4°C at a barometric pressure of 760 mm Hg. If the barometric pressure in a laboratory was 720 mm Hg, would the observed boiling point of rubbing alcohol be high or lower than 82.4 ℃ ? If the barometric pressure in a laboratory was 720 mm Hg, the boiling point of rubbing alcohol would be lower. 7.) Describe the proper technique for inserting a thermometer into a rubber stopper. Using glycerine as lubricant and protecting your hands with a towel, insert the top of the thermometer about an inch through a rubber stopper in such a way that the thermometer can still be read from 50 ℃ to 100 ℃ . 8.) What are the four pieces of safety equipment present in each lab? Give a brief description of how and when to use them. Eyewash station/ safety showers - to wash your eyes/ body in case of any hazardous chemicals spill on you. Fire extinguisher - in case of a fire occurs at the workstation. Fire blanket - in case someone's clothes get on fire during an experiment. Safety goggles - to protect one’s eyes from fumes and chemicals 9.) Safety glasses should be worn at all times while in the laboratory regardless of whether you are working on your experiment or not. True 10.) To determine the safety of a chemical read the label. True 11.) Bunsen burners should never be left unattended. True 12.) Never inhale chemical vapors. True 13.) One is allowed to work in the chemistry laboratory before your lab instructor is present. False

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14.) Dispose of all chemicals as directed by your lab instructor. True 15.) Do not fool around in the laboratory. True 16.) Broken glass should be in the broken glass boxes in your lab. True 17.) Clean up solid and liquid spills immediately. True Conclusion : The purpose of this experiment is to identify an unknown substance using “micro” techniques by finding the physical property of the substance such as the boiling point. This experiment also dealt with practicing temperature calibration which was utilized throughout. The examination of the physical properties such as clear liquid, colorless, and alcohol-like aided us to come to the conclusion that the unknown substance 886 was ethanol. The variable that made it clear that the unknown substance was ethanol was the boiling point as the average of the observed boiling point was 72 ℃ . The freezing point and boiling point of the water helped to calibrate the thermometer. The thermometer reading helped determine the error of 5.2 ℃ in the boiling point and 1 ℃ for the freezing point.