Analysis of a Volatile Liquid Essay Sample
The intent of this experiment was to utilize assorted methods of analysis to find the individuality of an unknown volatile liquid. In the first portion of the experiment. the molecular mass was found by utilizing H2O to happen the volume of a flask through computations and this every bit good as the mass of the gas of the unknown liquid were put into the a manipulated version of the ideal gas equation to find the molar mass of the liquid. which was 14. 21g per mole. The following portion was used to find the denseness of the volatile liquid. First the volatile liquid was placed in a pyncometer and massed ; H2O was so placed in the same ( now clean and empty ) pyncometer and massed. The denseness equation was manipulated utilizing the information for H2O to work out for the milliliter of the capillary tubing. This new information was used to happen the denseness of the liquid. which was 1. 33g/mL. The last portion of the experiment was used to find the boiling point of the volatile liquid. A trial tubing was placed inverted in a flask filled with the unknown liquid that was in a H2O bath warming.
When bubbles from the trial tubing slowed and began to travel back into the trial tubing. the temperature was taken and this served as a measuring of the boiling point. The mean measured boiling point was 60. 2°C. The mensural information was unequal to place the liquid with. The unknown liquid was revealed to be methanol ; the revealed individuality could so be used to compare the informations to the existent information for methyl alcohol. The molar mass was found to hold a per centum mistake of 55. 6 % . the denseness had a per centum mistake of 68. 1 % and the boiling point had one of 6. 95 % . The measured informations for the boiling point was reasonably accurate. but the molar mass and the denseness both had really big per centum mistake. The grounds for this will be discussed more in the treatment.
Boiling Point
Average Boiling Point: ( 63. 2+59. 3+58. 1 ) /3= 60. 2° C
The mean boiling point was found by adding each boiling point measured in each of the three tests and spliting this value by three.
Percentage Mistake: { ( 64. 7-60. 2 ) /64. 7 } x100=6. 95 %
The per centum mistake was found by deducting the existent value from the theoretical and so spliting this value by the theoretical. This value is so multiplied by 100 to happen a per centum.
Molar Mass
Volume of the flask: 32. 18g/0. 9975g/mL=32. 26mL
32. 26mL/1000=0. 03226
The denseness of H2O at room temperature was found to be. 9975g/mL. The denseness equation was manipulated so that the volume of the container could be found by spliting the gms of H2O in the flask by the denseness of H2O. This was so converted to litres by spliting the sum of milliliter by 100 because there are 1000 milliliter in a litre.
Mass of gas: 29. 129-29. 111= . 018g
To happen the mass of the gas. the mass of the flask was subtracted from the mass of the flask with gas in it.
Molar mass of the volatile liquid: { . 018g ten 0. 0821 ten 298K } / ( . 960atm ten. 03226L ) =14. 21g To happen the molar mass the ideal gas equation is manipulated to happen the molar mass. The equation was MM=gRT/PV. The gm of the gas was multiplied by the R invariable and the temperature of the room. Then. this value was divided by the force per unit area of the room multiplied by the volume of the container.
Percentage Mistake: { ( 32. 04-14. 21 ) /32. 04 } x100=55. 6 %
The per centum mistake was found by deducting the existent value from the theoretical and so spliting this value by the theoretical. This value is so multiplied by 100 to happen a per centum.
Density
Volume of Pyncometer: . 015g/ . 9975g/mL= . 015mL
The denseness of H2O at room temperature was found to be. 9975g/mL. The denseness equation was manipulated so that the volume of the pyncometer could be found by spliting the gms of H2O in the pyncometer by the denseness of H2O.
Density of Volatile Liquid: . 0209g/ . 015mL=1. 33g/mL
To happen the denseness the mass of a substance is divided by the volume so the gm of the liquid were divided by the milliliter of the container.
Percentage Mistake: { ( | . 791-1. 33| ) / . 791 } x100=68. 1 %
To happen the per centum mistake the existent consequence is subtracted from the theoretical and the absolute value is taken for this value. This value is so divided by the theoretical and multiplied by 100 to happen a per centum.
Calculation Summary Data Table
Calculation| Found Value|
Average Boiling Point| 60. 2°C|
Percent mistake of boiling point| 6. 95 % |
Volume of flask| 0. 03226L|
Molar mass of the volatile liquid| 14. 21g|
Percent mistake of Molar mass| 55. 6 % |
Volume of Pyncometer | . 015mL|
Density of Volatile Liquid| 1. 33g/mL|
Percent Error of Density| 68. 1 % |
Discussion:
The intent of this experiment was to analyse an unknown volatile liquid with assorted methods in order to place the liquid. This experiment can besides be used to find which methods of designation were the most accurate in placing the unknown liquid after the individuality was revealed. The unknown volatile liquid was methanol. The first portion of the experiment was to measure the molar mass of the volatile liquid. A flask was given a screen of aluminum foil and there was a pinhole put in the top. Some of the liquid was added and so evaporated by heating it in a H2O bath and the flask was massed following each subsequent adding and vaporizing of liquid. The mass of the gas was found this manner ( the mass of the flask with gas in it was subtracted by the original mass of the flask ) ; it was found to be. 018g. The volume of the flask was found by make fulling the flask with H2O and utilizing its available informations about denseness and its mass to happen the volume through a manipulated denseness equation. The molar mass was found by stop uping in this information every bit good as the temperature and force per unit area of the room and the changeless R into a manipulated ideal gas equation.
The molar mass can be found this manner because of the ideal gas theory. If any gas is non placed under utmost temperature or force per unit area conditions. it should in theory behave ideally and the equation can work. Since the liquid. and subsequently gas. used in the experiment was under close to ideal force per unit area conditions and normal temperature conditions. the ideal gas equation should be reasonably accurate. The molar mass that was found was 14. 21g. However. the existent molar mass of methyl alcohol is 32. 04. This means that there is a 55. 6 % per centum mistake. The molar mass that was calculated was much lower than the existent. which accounts for the really big per centum mistake. An mistake that could hold caused this is that some of the gas may hold escaped organize the pinhole in the aluminium foil. as the hole was larger than what would be the size of a pin. This would do the gms of the gas to be less and this besides lowers the molar mass rather a spot. which accounts for the really big per centum mistake. The molar mass of a substance is a good manner to place a substance because it is alone to the composing of a substance. However. the molar mass did non function as a good manner to place the methyl alcohol in this experiment because of the big per centum mistake. The following portion of the experiment was to cipher the denseness of the unknown volatile liquid.
The liquid was placed in a pyncometer and massed and so after the pyncometer was emptied H2O was placed in the same pyncometer and massed. Besides the mass of the empty pyncometer was taken. From this information the denseness can be found because the denseness and mass of the H2O can be used to happen the volume of pyncometer. From the volume and the mass of the unknown liquid the denseness can be calculated and it was found to be 1. 33g/mL. Density is a good manner to place a substance because denseness is reasonably alone. Not many substances. if any. will hold the same exact denseness. This is because denseness is the mass of the substance divided by the volume and small to no substances portion the exact same standards to hold the same denseness. The existent denseness of methyl alcohol is. 791g/mL. The per centum mistake of the denseness is 68. 1 % . Because this per centum mistake is so big there must be a really big mistake in the experiment. A possible mistake could be that there may hold been extra of the methyl alcohol in the pyncometer before the H2O was placed in it. This would change the deliberate volume of the pyncometer to be less than it really was. With the volume being less. this would do the denseness be much larger than it should be. which accounts for the really big per centum mistake.
The concluding portion of the lab was to mensurate the boiling point of the unknown liquid. A beaker of the liquid was placed in a H2O bath and heated with an upside-down trial tubing placed in the liquid. After heating. a watercourse of air bubbles would come from the upside-down trial tubing. At some point. the bubble were no longer air. but were really methanol vapour. Once there was a steady watercourse of bubbles. the beaker with the liquid was removed from the H2O bath and as the bubbles stopped. This is when the temperature was taken. This is because as the bubbles were traveling. the vapour had greater force per unit area than the ambiance. but when they stopped before traveling back into the trial tubing. the atmospheric force per unit area was equal to the vapor force per unit area.
The boiling point of a substance is when the vapour force per unit area equals the atmospheric force per unit area. so this is why it was taken at that minute. The boiling point of a substance is really alone for these grounds. The mean boiling point that was measured was 60. 2° C. The existent boiling point of methyl alcohol is 64. 7°C. This means that the per centum mistake of the boiling point was 6. 95 % . The mistake is non that great. but an mistake that could hold accounted for a lower mensural boiling point is that the thermometer used takes a long clip to demo the right temperature. There is a slowdown clip where the thermometer does non demo the right reading. This would do the mensural boiling point to be lower than the existent and this histories for the mistake. Post Lab Questions
1. The molar mass that was found was 14. 21g. However. the existent molar mass of methyl alcohol is 32. 04. This means that there is a 55. 6 % per centum mistake ( { ( 32. 04-14. 21 ) /32. 04 } x100=55. 6 % ) . The deliberate denseness found to be 1. 33g/mL. The existent denseness of methyl alcohol is. 791g/mL. The per centum mistake of the denseness is 68. 1 % ( { ( | . 791-1. 33| ) / . 791 } x100=68. 1 % ) . The mean boiling point that was measured was 60. 2° C. The existent boiling point of methyl alcohol is 64. 7°C. This means that the per centum mistake of the boiling point was 6. 95 % ( { ( 64. 7-60. 2 ) /64. 7 } x100=6. 95 % ) . 2. The method that produced informations that was closest to the existent information for methyl alcohol was the trial for boiling point. which merely yielded a per centum mistake of 6. 95 % . This mistake is non big. but it still could non once and for all lead to the designation of the liquid. There are many other substances with boiling points near to 60°C. When the other information is included and used to place the liquid. it is impossible to once and for all place the substance as the right liquid methyl alcohol because the informations strays so much from the existent information. 3. The cardinal thought of the Ideal Gas Model relies on the thought that the gas is acting ideally.
This means that there are no intermolecular forces between the molecules of the gas. the molecules obey Newton’s jurisprudence of gesture. the molecules move in all way with equal chance. and the molecules undergo elastic hits with the walls. The volatile liquid should hold behaved ideally because it was non tested under utmost force per unit area or temperature conditions. both of which cause gasses to no longer behave as ideal. The fact that it should hold behaved as ideal is the really ground that the ideal gas equation could be used. 4. These methods of placing the molar mass. denseness. and boiling point could non be used with Ga because it is non a liquid at room temperature and its boiling point is really high. In proving the molar mass and the boiling point. the Ga would hold to be heated to really high temperatures ( each clip for the vaporisation of the Ga ) and the lab stuffs would non be able to heat it up to the necessary temperature. This temperature would besides hold to be sustained for massing. and this would be impossible in the lab conditions. Octane could be tested. but it is non a liquid at room temperature so the increased temperature would hold to be sustained for proving.
It is besides non every bit volatile as methyl alcohol and would turn out hard to place because it has many different isomers. each with a distinguishable molar mass and denseness. Butane could in theory be tested. but it is much more volatile than methyl alcohol and would even hold to be cooled to act as a liquid. Because of this. it is really hard to prove the boiling point in the method that was used for the lab. The H2O bath that the methyl alcohol was heated in. would non hold to be heated and the lab could non be performed at room temperature. it would necessitate to be done at around 1°C. which is non really plausible for the lab conditions. Out of all of these substances H2O would be the easiest one to prove as it is a liquid at room temperature and it has a reasonably low boiling point. as does methyl alcohol.
However. much of the information was determined by utilizing H2O itself to happen missing variables and so the H2O would be compared with itself. This does non restrict its ability to be tested in any manner. but it does let for a batch mistake in comparing the unknown. but in secret H2O with itself. 5. The measurement mistakes for the molar mass computation piece of the lab include an inaccurate measuring of the mass of the gas in the flask and in inaccurate computation for the volume of the flask. For the mass of the gas. some escaped through the pinhole in the top of the flask and this greatly lowered the molar mass. The volume of the flask should hold been greater. which really made the molar mass somewhat more than it should hold been. These mistakes did non call off each other out as the molar mass was still much lower than it should hold been. This means that the mass of the gas affected the informations much more than the inaccurate volume did.
Beginnings:
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