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Chapter 12 intermolecular forces
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Essential Chemistry Written Report Introduction The Boiling Point can be defined as the temperature at which a substance bubbles, and converts from a liquid form to a gaseous form, it is the temperature at which the vapour pressure from the liquid is equal to that of the atmospheric pressure (eds. Hanks & Potter 1971). Molecular structure is the location of atoms, groups or ions relative to one another within a molecule, as well as the number and location of chemical bonds in the molecule as well. The boiling point of a substance depends on both, the molecular structure and intermolecular forces, which are the forces of both repulsion and attraction, which act between neighbouring particles (ed. Daintith 2008), within the compound. When a substance …show more content…
The difference in boiling point can be attributed to the differences in functional groups, intermolecular forces, as well as a molecules size and shape. The first separation we can create between the allocated molecules, to identify which has the highest boiling point, is done by identifying and using the functional groups of the molecules. Pentanal, is an aldehyde, whilst 1-pentanol, 1-hexanol, and 3-methyl-1-butanol, are all alcohols, which shows that pentanal, has the weakest intermolecular force (dipole-dipole interactions) present in the allocated molecules. Thus shows that pentanal would have the lowest boiling point, which is shown by the literature as well. Between the remaining molecules we can then split them further, with 1-pentanol, and 1-hexanol grouped together, and 3-methyl-1-butanol on its own. This separation can be attributed to the structure of the molecules. Whereas 1-pentanol, and 1-hexanol are simply carbon backbones without any methyl groups coming off. This forms a separation as 3-methyl-1-butanol is an alcohol like the others but with a methyl group extending from the third link in the carbon
Every 5 minutes, a small amount of mixture was dissolved in acetone (0.5 mL) and was spotted onto a thin layer chromatography (TLC) plate, which contained an eluent mixture of ethyl acetate (2 mL) and hexanes (8 mL). The bezaldehyde disappearance was monitored under an ultraviolet (UV) light. Water (10 mL) was added after the reaction was complete, and vacuum filtrated with a Buchner funnel. Cold ethanol (5 mL) was added drop-by-drop to the dried solid and stirred at room temperature for about 10 minutes. Then, the solution was removed from the stirrer and place in an ice bath until recrystallization. The recrystallized product was dried under vacuum filtration and the 0.057 g (0.22 mmol, 43%) product was analyzed via FTIR and 1H NMR
The C-H (sp3) hydrogens from our product displayed at wavelength 2959 cm-1 correlates to the methyl groups located on the ends of isopentyl acetate4. A really prominent, strong peak located at 1742 cm-1 shows that a C=O ester stretch is located in the product, along with at 1244 cm-1 the spectrum shows a strong peak representing the C(=O)-O stretch that is crucial to the structure of isopentyl acetate. Shown in my IR spectrum is a weak O-H (H-bonded) peak at 3464 cm-1 which shows that I have an impurity of isopentyl alcohol in my product. Isopentyl alcohol has similar boiling points and density as my product so the impurity could have easily boiled out with the isopentyl acetate during distillation. The isopentyl alcohol was also present in my 1H-NMR spectrum backing up the impurity peak at 3464
It was learned that changing the volume of the same substance will never change the boiling point of the substance. However having two different substances with the same volume will result in two different boiling points. The purpose of this lab was to determine if changing the volume of a substance will change the boiling point. This is useful to know in real life because if someone wanted to boil water to make pasta and did not know how much water to
Felder, M. Richard, Elementary Principles of Chemical Processes, 3rd ed.; Wiley: New Jersey, 2000; p 631.
As shown in figure 3, the isoborneol accounted for roughly 35.51% of the compound with a peak at 12.515, while the borneol which peaks at 12.619 accounts for roughly 8.67% of the mixture
Therefore, the gas chromatography could not be performed to determine its composition. The ratio of the three samples obtained, were not all accurate. The first sample, of pure hexane should have had a ratio close to 100% hexane to 0% heptane. The second ratio should have been close to 50% hexane to 50% heptane and the third should have been the reverse of the first sample, with 0% hexane to 100% heptane. The boiling point of hexane is around 65°C and the boiling point of Heptane is 100°C. The first sample’s error could have occurred due to the late extraction of the sample. When the boiling point was reached, the extraction of the sample from the distillation vial should have occurred immediately, not doing so caused some of the vapors from heptane to be included into the first sample. This could be prevented next time by lowering the heat of the Variac transformer, which would have allowed for the heating of the compound to be slower than what it was
Since, the expected weight was 50.63 mg the percent yield is 59.3%. A TLC was conducted on this final product and a faint spot of 4-tert-butylcyclohexanone still appeared in lane 3 of the plate; meaning the reaction did not fully go to completion. The Rf values were 0.444, 0.156, and 0.111, where the lowest value is the trans isomer and the highest value is the ketone. This affected the IR spectrum conducted by having a carbonyl group peak at 1715 cm-1 which should not be present if all the product was 4-tert-butylcyclohexanol. However, the IR spectrum still showed peaks at 3292 cm-1 (hydroxyl group), 2939 cm-1 (sp2 carbon bonded to hydrogen) and 2859 cm-1 (sp3 carbon bonded to hydrogen) which support the presence of the alcohol. The accepted melting point of 4-tert-butylcyclohexanol is in the range of 62 – 70˙C (Lab Manual). The two melting point measurements using the Mel-Temp® machine gave ranges of 57 – 61˙C and 58 – 62˙C, which is not exact due to some 4-tert-butylcyclohexanone being present that has a low melting point of around 47 – 50˙C
If the pot is close to the heat source, more heat is directed to the water so it will be heated faster. Alcohols: Different alcohols have different bond structures, some bonds need more energy to break them than others, and some release more energy when they are broken. Temperature increase: I could change the amount the temperature has to rise before I record my results. This will only affect the amount of fuel used, so hasn’t got much relevance to the experiment. If I did a calculation from the results I have for the temperature rising to 10 c then I would be able to work out how much fuel would be used, if I heated the water to 50 c. X 10 x 50" By dividing the amount of fuel used by the temperature raised you will be given the amount of fuel used per c. If you multiply the amount of fuel used per c, by the amount you want to find results for, you will be given an exact amount for how much fuel would be used if you heated the water to that specific temperature.
...rivate and taking into account there boiling point and volatility the Gc retention time will increase, in accordance to the chain going up, so in this case the pentyl derivative would go first then the butyl derivative.
This chemistry book report is focus on a book called “Napoleon's buttons: How 17 molecules changed history” by Penny Le Couteur and Jay Burreson. The publisher of this book is Tarcher Putnam, the book was published in Canada on 2003 with 17 chapters (hey the number match the title of the book!) and a total of 378 pages. The genre of this book is nonfiction. “Napoleon's Buttons” contain a fascinating story of seventeen groups of molecules that have greatly changed the course of history and continuing affect the world we live in today. It also reveal the astonishing chemical connection among some unrelated events, for example: Chemistry caused New Amsterdamers to be renamed New Yorkers and one little accident of detonating cotton apron in a minor housekeeping mishap lead to the development of modern explosives and the founding of the movie industry.
Theory: Steam distillation uses boiling point to separate organic liquid and water. The organic compound must be immiscible with water, have a high vapor pressure at 100˚C, and may decompose before boiling point is reached. Steam distillation increases the vapor pressure of water more than the vapor pressure of the organic compound as temperature rises to reach the boiling point of the mixture which is a little less than 100 ˚C (boiling point of water) but a lot less than 254 ˚C (boiling point of eugenol). Since the liquids are immiscible, the total vapor pressure only depends on the vapor pressure of each component added together and not the mole fraction leading to a higher vapor pressure which corresponds to the lower boiling point.
The link between the number of carbon atoms in a fuel with the amount of energy it releases. Alcohols generally belong to compounds whose molecules are based on chains of carbon atoms. They usually contain one oxygen atom, which is joined to a carbon atom by a singular bond. This makes them different from other compounds.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
molecules its size it would have a boiling point of -75øC and a freezing point of -125øC4.