Thursday, January 30, 2020

Fractional Distillations Essay Example for Free

Fractional Distillations Essay In this experiment we aim to demonstrate that we can separate two volatile compounds from a mixture due to the different chemical properties of each compound. We will accomplish this by a separation procedure known as distillation, which relies on each compound having a distinct and separate boiling point. Our pure products will be analyzed with gas chromatography to determine the success of the distillation. Procedures The experiment was performed as stated in the course textbook: Pavia, D. L., Lampman, G. M., Kriz, G. S., Engel, R. G. Introduction to Organic Laboratory Techniques: A Microscale Approach. 2007, 4th Ed. Pp 51—57. . Data The distillation curves for our simple and fractional distillation (See page 3) clearly demonstrate that fractional distillation separates the two compounds more completely. The boiling point (bp) of our unknown compounds was taken from the flat regions of the fractional distillation curve. Our unknown mixture contained hexane (bp 69  ºC) and toluene (bp 110.6  ºC). Analysis via gas chromatography allowed us to determine the relative percentage of hexane and toluene at fractions near the beginning and end of our distillations. Relative percentages have been recorded in the table below, and our calculations are shown on page 5. Conclusion This week we utilized two methods of distillation (simple and fractional) to separate a mixture of two volatile compounds. We found that while the simple distillation separated the majority of the two compounds near the beginning and the end of the distilling process, fractional distillation produced much more pure fractions. In simple distillation the column was shorter, allowing less room for the two different compounds to fully separate. While heating the round-bottom flask the hexane molecules gain higher kinetic energy faster than the toluene molecules due to their lower molecular weight and lesser intermolecular forces. The longer fractional  distillation column allowed the hexane molecules with higher kinetic energy to separate from the lower-energy toluene molecules. After viewing the gas chromatograph data from the fractional distillation we saw that our unknown compounds had almost completely separated, while the fractions from the simple distillation were less pure. Although distillation is a good separation technique it is still necessary to ensure that proper steps are taken to reduce the chances of error. Failure to add a boiling chip to the round-bottom flask could allow the mixture to heat unevenly. This could allow molecules with a higher boiling point to gain kinetic energy before the molecules with the lower boiling point, which would create impure fractions. Watching the rate of temperature increase is also important. Allowing the temperature to increase too quickly can cause impurity for the same reason. We forgot to add the boiling chip to the round-bottom flask in the simple distillation, which could have contributed to the mixture of toluene and hexane that we saw. We made sure to include the boiling chip in the fractional distillation, however, and did not observe any problems. Even though both hexane and toluene are volatile, they have different chemical properties to allow for separation and analysis. Hexane is a hydrocarbon with no dipole moment or double bonds. This means that it has few intermolecular interactions, and will have a lower boiling point. It also has a lower molecular weight than toluene, so it will appear first on the gas chromatograph. Toluene has a benzene ring with a methyl group attached. Toluene has greater intermolecular forces than hexane because the benzene ring withdraws electrons from the methyl group. This creates a slight polarity to the molecule that increases intermolecular forces and increases the boiling point. Since toluene has a greater molecular weight than hexane it will appear second on the gas chromatograph. This experiment illustrates how useful the different properties of compounds can be while trying to purify mixtures of compounds.

Tuesday, January 21, 2020

Early Warning Signs in Elie Wiesels Night Essay -- essays research pa

Denying Life As a son watches his mother take her last breath on her deathbed, an overwhelming grief sets in. Although knowing that his mom smokes and drinks, he never told her to quit or ease up because he thought his mother can never die. In this case, the offset of this denial is his mom’s early death but, the denial by the Jews during 1942, caused a far more superior calamity, six million deaths! Alas, just like the boy who lost his mother, the Jews have signs and warnings to escape the invasion and Elie Wiesel does a superb job of incorporating that in his book, Night. These overlooked chances, or motifs, are Moshe not getting the respect for his word, uncomprehending the news that is given to the Jews, and the misjudgment of how evil a man Hitler is. If one is saved from a massacre of his or her own people, it is indispensable that he or she return back to his or her homeland and warn others of their approaching fate. This should give them enough time to pack their belongings and flee from their invaders. In Elie Wiesel’s painful memoir Night, there is a minor character that experiences this sequence, and his name is Moshe the Beadle. The only difference in the cycles is that when Moshe returns, nobody believes him of his incident. When Moshe returns, one citizen exclaims, â€Å"’He’s just trying to make us pity him. Or even: ‘Poor fellow, He’s gone mad.’† The cause of this persecution may be because of his â€Å"waiflike timidity,† but even so, heeding Moshe’s advice could have granted the Jews of Sighets’ protection from the Nazi concentration camps. An additional reason why Moshe was not given the proper respect might be because he was deeply religious. The o ther members in town may have been led to believe that Moshe had s... ...f the major Optimism of the Jews is that they could not comprehend the killing of all their people. They see it as a task that contains no possible way to be fulfilled. They justify it by saying â€Å"Was he going to wipe out a whole people? Could he exterminate a population scattered throughout so many countries? So many millions! What methods could he use?† (6). The answer to their question is yes but there is many chances to escape this fate, although the Jews of Sighet deny it. Understating Hitler, denying the media, and not realizing the depth of Hitler’s evil, were all the motifs shown above and is proof on how the Jews of Sighet deny their warning signs of an upcoming holocaust. Heeding these signs may have granted many of them life in a place that manufactured death. And when the race toward death began, it was the village idiot that came out to be the smartest.

Monday, January 13, 2020

Analysis of Environmental Issues and Economic Performance

Analysis of environmental issues and economic performance and population density Executive summary The main goal with the report was to analyse the relationship from 16 different countries on how, if any, CO2 emission per capita is getting affected by population density and GDP per capita by using descriptive statistics and regression. The conclusion is that CO2 emission per capita is affected by changes in GDP per capita and that population density has no significant relation to CO2 emission per capita. Introduction Global warming is one of the biggest problems in the international societies today.The politician keeps discussing how they can find solutions together to decrease the CO2 emissions worldwide. In this report we will try to examine if well-established countries have a higher CO2 emissions and we will examine how population density are affecting emission in our society today. Aim The aim with this report is first to examine the relationship with GDP per capita and CO2 emis sion and population density and CO2 emission. Then we will examine if high GDP per capita leads to higher CO2 emission per capita and if countries with low population density are polluting more than countries with high population density.Hypothesis 1. 1 I believe that a country with high GDP are more likely to have a higher CO2 emission per capita since a country with high GDP are more likely to have higher productivity achieved through higher energy use. We will then start with measuring the linear association between these variables. H0: ? 0 1 GDP? 0 (Correlation) H1: ? 0=? 1 GDP=0 (No correlation) Hypothesis 1. 2 I believe that a country with high population density are more likely to have a lower CO2 emission per capita since the inhabitants need travel shorter and less often.We will therefor measure the linear association for CO2 emission per capita and population density. H0: ? 0 2 pop. density? 0 (Correlation) H1: ? 0=? 2 pop. density=0 (No correlation) Main hypothesis We wan t to find out how much linear association the two variables has on CO2 per capita. This can be done with this model: CO2per capita = ? 0+ ? 1 GDP+? 2 pop. density+ ? H0: ? 1 GDP? 0 H1: ? 1 GDP=0 H0: ? 2 pop. density? 0 H1: ? 2 pop. density=0 We can then see how strong the association these two variables are against the dependent variable CO2 emission per capita. Further on we want to test the significance of these variables.Data and descriptive statistics The data (GDP per capita, CO2 per capita and population density) in this report is a sample of 16 different countries and are downloaded from the International Monetary Fund, US department of Energy and OECD. All the data are ratio scale and are continuous. Some potential problems with the associated data is: * Some countries may have a high productivity achieved by the efficient labour force and not trough higher energy use. Both ways of high productivity leads to higher GDP per capita, its unlikely to achieve it by efficient labo ur force, but it can occur. Some countries (e. g. Australia) may have low population density although they mainly have big populated cities since they have a large amount of landmass that is not suitable for life. * The different data is not from the same years. CO2 emission per capita is from 2004, population density is from various years and GDP per capita is from 2010. To get an idea of how the dataset looks like we need to use descriptive analysis. Mean: x=xn Median: x=n+12th S. D: sx=x2-nx2n-1 Sample variance: s2=x2-nx2n-1 Range=xh-xlFor Co2 per capita the mean is 9,285 and the median is 9,49, this will suggest that the data is normally distributed and we can see in the graph in the appendix that there are 8 countries on each side of the mean. The skewness is 0,71, since the number is positive it will imply that Co2 emission per capita is slightly skewed to the right. The mean (26226) and median (27407) for GDP per capita show that this data is normally distributed as well. We can also here see that there are 8 countries on both side of the mean. The skewness for GDP per capita is close to zero (0,08) and therefor the distribution is close to symmetric.For population density we have 10 countries underneath the mean. This will imply that the data is not perfectly normally distributed. We can also see that mean (151) and the median (118) differs a bit too much too be normally distributed. Since the mean is higher than the media it suggest that the mean is affected by the high extreme values in the distribution like South Korea. The skewness for population density is 0,94, this show that the distribution is skewed to the right. It is important to remember that the data sample is less than 30 and therefor it makes it difficult to determine if the data is normally distributed or not.In all the 3 different data’s we see that the range is high, this is due extreme values on both sides of the mean (countries in totally different stages when it comes to wea lth, industry, population, size and general development). The high spread within the distribution will therefor lead to and high S. D, it’s also important to notice that the sample is relative small and will not give a totally correct picture. Correlation First we will start with to calculate the Pearson correlation coefficient to measure the linear association between the two variables in hypothesis 1. 1 and 1. 2.After that we will test the significant of the correlation coefficient. The reason we will use the Pearson correlation coefficient instead of Spearman correlation coefficient is that the data are continuous and in ratio scale. sx=x2-nx2n-1 sy=y2-ny2n-1 sxy=i=1n(xi-x)(yi-y)n-1 rxy= sxysxsy t=r1-r2n-2~tn-2 For the calculation see table 1 and 2 in the appendix. The table and the graph 1. 1 show that there is a strong relationship between Co2 emission per capita and GDP (0,7319). In graph 1,2 and the table we see that Co2 and population density have a weak negative corr elation (-0,3118).Further on we will need to use a t-test in order to determine the significant of the correlation coefficient and to find out if we are going to keep or reject our hypothesis 1. 1 and 1. 2. critical value of t: t(n-2,? 2)=t(14,0. 25)=Â ±2,145 (with 95% confidence interval) The t value in the table shows that there is a significant relationship between Co2 emission per capita and GDP since 2,145

Sunday, January 5, 2020

The Solar Of Solar Energy - 1637 Words

Interest in solar energy has been growing in recent years. Solar energy is abundant, clean and renewable. There are two main methods to tap solar energy, i.e. with PV cells and with solar collectors. The former converts sun light directly to electricity while the latter collects the solar thermal energy (heat) to be used for various applications. Solar collectors have been in existent for many decades. Their usages are experiencing resurgence in the recent years due to the interest in renewable energy sources. Strongly increased number of solar heating plants have been built and are under construction throughout the world. The solar collectors used in the solar heating plants are flat plate solar collectors and often the volume flow rate through the collector field is varying. The integration of solar thermal systems into buildings to meet energy requirements of buildings (for domestic hot water, space heating, air-conditioning and lighting) is supported by many researchers in differ ent parts of world. Many types of solar collectors are commercially available; they differ in design and performance and, of course, in price. They have to meet different demands in operation, configuration and meteorological conditions. Thermal applications are becoming focal point with increasing attention in the solar energy research area as it has high performance in energy storage density and conversion efficiencies. Solar energy collectors are particular kind of heat exchangers thatShow MoreRelatedThe Solar Of Solar Energy1304 Words   |  6 Pagesthat uses Solar? Solar power is a great way to save money as well as conserve energy. Solar panels convert sunlight into usable energy for housing, businesses, sections of properties, and even stuff like pool equipment. 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