Lab Report: Diffusion and Osmosis

Lab Report: Diffusion and Osmosis Hypothesis and Prediction: This lab was done to examine and comprehend how diffusion and osmosis works in diverse molarity of sucrose. Also how the solutions permeates through different mediums. Methods: Part A: Diffusion and Osmosis: A 30 cm piece of 2.5 cm dialysis that has been soaked in water was obtained. The beginning of tubing was tied off, forming a bag with an open end that was rubbed between the fingers till separated. 15mL of the 15% glucose and 1% starch solution was placed into the bag and the ending of the dialysis bag was tied off, leaving some space for the development of the content within the dialysis bag. The color of the solution was recorded and was tested for the presence of glucose. Distilled water was poured into a 250 mL beaker (two-thirds of a cup) with about 4mL of Lugols solution (IKI). The color of the sucrose in the beaker was recorded and was tested for glucose. The dialysis bag was then submerged into the beaker of solution and left to stand for about 30 minutes (or until there was a color change in the dialysis bag or beaker).Once the bag was done soaking in the beaker, the final color of the solution in the bag and the beaker was recorded. The liquid in the bag and the beaker was then tested for the existence of glucose. Part B: Osmosis Six strips of 30 cm presoaked dialysis tubing were obtained. For each strip, an end was tied and roughly 25 mL of different solutions (distilled water, 0.2 M sucrose, 0.4 M sucrose, 0.6 M sucrose, 0.8 M sucrose and 1.0 M sucrose) was poured into their individual bags. Most of the remaining air was then removed from each bag by bringing the bag between two fingers and tied off at the opened end. The outside of each bag was then bathed to wash away any sucrose that spilled when filling the bag. The exterior of each bag was then blotted and the initial mass of each bag was weighed and recorded. Distilled water was then filled into six 250 mL beakers. Each bag was then emerged into one of the six filled beaker and the beakers were labeled by which bag of solution was emerged in it. The bags stood in the beaker for half an hour. When the time was up, each bag was removed, blotted and the mass of each bag was recorded. The mass difference was calculated and then using the equation: Percent change in mass = Final Mass – Initial Mass/Initial Mass x 100. The individual and the class average of the percent change in mass were then graphed. Part C: Water Potential 100 mL of the given solution was poured into six different labeled 250 mL beaker. The potato was then sliced into discs that were just about 3 cm thick. A cork borer (about 5 mm in diameter) was then used to cut four potato cylinders for each beaker, a total of 24 potato cores. Until the mass of cores were weighed by fours and recorded, the potato cores were kept in a covered beaker. Four cores were then put into each beaker of sucrose solution. Plastic wrap was then given to cover the beakers, preventing evaporation when left to stand overnight. The next day, the cores were then removed from the beakers and were blotted gently on a paper towel. Their total mass was then determined and recorded. The mass difference was calculated and then using the equation: Percent change in mass = Final Mass – Initial Mass/Initial Mass x 100. The individual and the class average of the percent change in mass were then graphed. Part D: Calculation of Water Potential from Experimental Data Determine the solute, pressure and water potential of the sucrose solution given and answer the questions about the possibility if zucchini cores were used with the sucrose solutions. Results: Part A: Diffusion and Osmosis Table 1.1-Presence of Glucose in Water through a Dialysis Bag Initial Contents Solution Color Presence of Glucose Initial Final Initial Final BAG 15% GLUCOSE and 1% STARCH Clear Clear Yes Yes BEAKER H20 + IKI Yellow (an olive oil color) Clear No Yes Part B: Osmosis Table 1.2: Individual Data of Change in Mass of Six Different Dialysis Bags Contents in Dialysis Bag Initial Mass Final Mass Mass Difference Percent Change in Mass a) distilled water 18.15 g 14.76 g 3.39 g -18.68% b) 0.2 M 19.40 g 17.33 g 2.07 g -10.67% c) 0.4 M 18.87 g 19.37 g -0.5 g 2.65% d) 0.6 M 19.83 g 19.68 g -0.15 g -0.5% e) 0.8 M 21.91 g 20.05 g -0.869 g -8.2% f) 1.0 M 18.78 g 18.07 g -0.71 g -3.7% Table 1.3: Class Data of Percent Change in Mass of Dialysis Bags Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Total Class Average Distilled Water -18.68% -2.2% -7.0% -7.2% -35.1 -8.8% 0.2 M -10.67% -22.3% -5.2% 1.8% -36.4% -9.1% 0.4 M 2.65% 6.2% 2.5% 3.9% 15.3% 3.8% 0.6 M -0.76% -3.8% -4.0% -6.55% -15.2% -3.8% 0.8 M -4.1% -26.3% -1.6% -3.78% -35.95% -8.95% 1.0 M -3.78% -3.27% -8.7% -29.4% -45.2% -11.3% Group 2, 4, 6 and 8 do not have any data for distilled water, 0.2M Sucrose, and 0.4M Sucrose and group 1, 3, 4 and 7 do not have any data for 0.6M Sucrose, 0.8M Sucrose and 1.0M Sucrose because of the lack of time. So, group 1 and 2 were paired up, 3 and 4, 5 and 6, and 7 and 8 to exchange data. Part C: Water Potential Table 1.4: Individual Data of Change in Mass of Potato Cores in Six Different Sucrose Solution Contents in Beaker Initial Mass Final Mass Mass Difference Percent Change in Mass Class Average % Change in Mass a) Distilled Water 2.39g 2.95g 0.56g 23.4% 23.3% b) 0.2M Sucrose 2.41g 2.69g 0.28g 11.6% 8.4% c) 0.4M Sucrose 2.47g 2.38g -0.09g -3.6% -3.7% d) 0.6M Sucrose 2.33g 1.98g -0.35g -15.0% -13.5% e) 0.8M Sucrose 2.46g 2.05g -0.41g -16.7% -19.9% f) 1.0M Sucrose 2.49g 1.95g -0.54g -21.7% -20.8% Table 1.5: Class Data of Percent Change in Mass of Potato Cores in Six Different Sucrose Solution Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Total Class Average Distilled Water 23.4% 18.9% 23.2% 27.5% 93% 23.3% 0.2M 11.6% 6.8% 5.0% 10.1% 33.5% 8.4% 0.4M -3.6% -3.7% -7.0% -0.4% -14.7% -3.7% 0.6M -15.02% -13.5% -11.16% -14.3% -54% -13.5% 0.8M -16.67% -22.5% -20.33% -20.2% -79.7% -19.9% 1.0M -21.69% -24.3% -24.39% -12.9% -83.3% -20.8% Group 2, 4, 6 and 8 do not have any data for distilled water, 0.2M Sucrose, and 0.4M Sucrose and group 1, 3, 4 and 7 do not have any data for 0.6M Sucrose, 0.8M Sucrose and 1.0M Sucrose because of the lack of time. So, group 1 and 2 were paired up, 3 and 4, 5 and 6, and 7 and 8 to exchange data. Part D: Calculation of Water Potential from Experimental Data Analysis: Part A: Diffusion and Osmosis From table 1.1 in this part of the lab, it is seen that IKI is flowing into the bag and glucose is flowing out of the bag. That is because of diffusion and osmosis. Knowing of this process is due to the color transformation of the bag, therefore showing that IKI has penetrated the bag. By testing the beaker for the existence of glucose, it was found that the glucose permeated through the dialysis bag, mixing with the IKI and H2O in the beaker. This is possible because as stated osmosis is a branched off form of diffusion, in which it is the diffusion of water through a selectively permeable membrane and glucose is one of the substance that is able to go through. IKI along with glucose is tiny enough to enter and exit the dialysis bag. Part B: Osmosis Both the individual and class data of percent change in mass is shown in graph 1.1. To receive the percent change in mass, the initial mass was subtracted from the final mass. The difference is then divided by the initial mass and 100 is then multiplied to the quotient. The product is then the percent change in mass. Osmosis is present due to the change in mass of the dialysis bag. The mass is different for each bag because of the sucrose in the bags different molarity. That establishes the amount of water that progresses in and out of the bag, which then changes the mass. Part C: Water Potential From testing the potato cores in different sucrose solution, graph 1.2 illustrates that on the best fit line, the molar concentration of sucrose, the sucrose molarity that shows the mass of the potato cores does not change, is 0.4M. So the lower the concentration of the molar concentration of sucrose, the percentage of the potato cores mass increases and anything with a higher concentration of the molar concentration of sucrose the percentage in the potato cores mass decreases. This is all because molecules of any sucrose with a higher concentration of 0.4M are too great to enter or exit into the potato cores. Part D: Calculation of Water Potential from Experimental Data It is given that the solute potential of the sucrose solution is calculated by using ψs= iCRT. ÃŽ ¨s is the solute potential, the variable â€Å"i† represents the ionization constant, variable â€Å"C† signifies the molar concentration, variable â€Å"R† standing for the pressure constant (R= 0.0831 liter bars/mole oK), T is the temperature oK (273+ oC of solution). Since it is the solute potential of sucrose that must be found, â€Å"i† is 1.0, due to the fact that sucrose does not ionize in water. From the information of â€Å"i†, â€Å"C† is determined to be 1.0 mole/liter. So the problem that has 1.0M sugar solution at 22 oC under atmospheric conditions would be answered like this: Since the formula is ψs= iCRT, then when filling in for the variables the equation is now: ÃŽ ¨s= -(1)(1.0mole/liter)(0.0831 liter bar/ mole oK) (273+22) à   ψs =-24.51 bars The water potential can then be figured out by the formula: ψ = ψp + ψs. By being able to solve for the solute potential, the product would then be used to solve for the water potential. And from the knowledge of knowing that the water pressure, ψp, is equal to zero the formula filled out would turn out as: ψ=0 + (-24.51 bars) à   ψ = -24.51 bars From the graph of the percent change in mass of zucchini cores in different sucrose solution at 27 oC after 24 hours it can be concluded that the molar concentration of solute within the zucchini cell is 0.35 moles. From knowing the molar concentration of solute within the zucchini cell, the solute and water potential can be answered. Solute Potential= -1(0.35moles/liter)(0.0831 liter bar/mole oK)(273 +27) à   = -8.73 bars Water Potential= 0 + (-8.73) à   = -8.73 bars This is an important piece of information because by knowing the water potential, it is possible to predict the direction of the flow of water. Water flows from an area of a higher water potential to and area of lower water potential; so if the information of the water potential of the solution in the beaker which the zucchinis were soaked was given, the information of where the water flows would be known. Conclusion: This lab was to understand how diffusion and osmosis worked. The data that was received was consistent at some times. For part A and D of the lab, the results and calculations were consistent, but part B and C showed little consistency. That is because part B and C when comparing the percent change in mass with others, the numbers varied. The difference of the mass was changed, for it maybe misleading, into percentage, there eliminating any size factor and to compare the results. Though when comparing the percents with one another, some of the difference was too great to receive any accurate data. Some possibilities that may have altered the outcome of the results include the ends of the dialysis bags not being tied correctly, the inaccuracy of pouring the solutions, not a thorough cleaning of the outside of the dialysis bag and incorrect calculation and measurements. This lab can be modified to get a more consistent data by wearing gloves when working with the solutions, so when one is done pouring and tying the dialysis bag, gloves can be removed to reduce any chance of the solution being on the outside of the bag. A more accurate and precise measurement of the solution and the tightness and method of tying the ends of the bags can be arranged to be the same. With those alterations to the lab, the chance of a more consistent data is higher. Should Humans Be Blamed For Global Warming? Should Humans Be Blamed For Global Warming? Global warming is the next big impact that will bring about a change in the weather patterns. By definition, Global Warming is the increase in average temperature that gradually warms the Earths atmosphere. It is a phenomenon, which has been on the rise but in the last century, the increase in the levels have been alarming (George Christodoulou, 2006).Global warming has caused a lot of changes to the environment in a negative manner. According to the study by the Intergovernmental Panel on Climate Change (IPCC), it is observed that the increase in global average temperature has been caused due to an increase in greenhouse gas concentrations (Slashman, 2007). Global warming can have many causes, but it is most commonly associated with human interference, specifically the release of excessive amounts of greenhouse gases (EPA, 2006).It is either caused by humans or natural causes. Global warming is no more a myth but a fast approaching reality, which in the long-term will bring the much feared ice age that will wipe out all living organisms on Earth. The latest IPCC report states widespread mass losses from glaciers and reductions in snow cover over recent decades are projected to accelerate throughout the 21st century, reducing water availability, hydropower potential, and changing seasonality of flows in regions supplied by melt water from major mountain ranges (e.g. Hindu-Kush, Himalaya, Andes), where more than one-sixth of the world population currently lives (Geneva, 2010). Global warming has caused a major increase of heat towards the earths atmosphere and it is still affecting us till today due to numerous human activities. Although some people think that global warming happens due to natural factors, it is scientifically proven that humans are responsible for global warming. The purpose of this paper is to point out the irresponsible people causing global warming and not to blame the natural factor for global. There are many scientific and logical factors of global warming that are caused by human activities. The main factor is due to the depletion of ozone layer of the atmosphere which happens in the stratosphere which is 30 miles above the earth. What is the function of the ozone layer? The ozone layer protects the earth from radiating ultraviolet (UV) rays. The ozone is made up from oxygen molecules named triatomic oxygen. The ozone molecules or the triatomic oxygen will absorb the UV rays. Eventually the triatomic oxygen will split into diatomic oxygen and a monoxide. This process is repeated as the monoxide combines with diatomic oxygen to produce ozone molecules back and protects. Thus, this helps to protect UV rays from entering the earths atmosphere. The UV rays will heat up the earth as it penetrates through directly without the shield of ozone layer. Every time 1% of the ozone layer is depleted, 2% more UV-B is able to reach the surface of the planet (Miller, G. Tyler Jr., 1987). The thinning of ozone layer happens due to human activities on the earths surface by burning and releasing harmful gases. As the ozone layer becomes thinner the UV rays will be trapped inside the earths atmosphere, therefore our earth becomes hotter. The shine of UV rays may cause skin cancer. In addition, it also dries up the earth and causes drought. Moreover it is because of the release of chlorofluorocarbon (CFC) gases the ozone layer depletes. Human being use air conditioners to make the hot environment cooler, but what they dont seem to realize is that they are making the atmosphere even hotter. Air conditioners releases CFC gas when it is turned on. Besides that, refrigerators also release CFC gases when the doors are opened. The CFC gas will react with the ozone layer. The triatomic oxygen will be split and the chlorine atom from CFC will combine with the diatomic oxygen gas. This will produce chlorine monoxide. Referring to the statement above, there will be no chance of the oxygen to recombine to form ozone molecules. As a result a hole is created in the ozone layer. Slowly they start infiltrating into the upper layers of the atmosphere and soon reach the ozone rich stratosphere, where they undergo major chemical changes (H. Khemani, 2010). The CFC gas will soon disintegrate and the chlorine atom will react with the ozone molecule and changes to oxygen molecule. As soon as the ozone layer changes to oxygen molecule the ozone layer will be depleted. The most shocking fact about CFCs is that they have exceptionally long atmospheric life which, in certain cases, even extends to 100 years. This means that if CFC refrigerants are leaked in the atmosphere, they will keep depleting the ozone layer for the next 100 years to come (H. Khemani, 2010). There are other materials used by humans that release CFC gas such as chemical sprays and the burning of Styrofoam materials. Furthermore, the increase of carbon dioxide level leads to climatic changes. Humans are the main people to emit green house gasses to the environment. They emit them in a variety of ways. The combustion of fossil fuel by human activities releases green house gases which is carbon dioxide and others. When there is an increase in the percentage of carbon dioxide in the air, the amount of heat captured by the carbon dioxide also increases (Bidisha Mukherjee, 2010). As the amount of carbon dioxide level increases in the atmosphere, heat is trapped inside the atmosphere and causes warming of the earth. Moreover, coal-burning of power plants also increases the carbon level in the atmosphere. Burning coal produces about 9 billion tonnes of carbon dioxide each year which is released to the atmosphere, and about 70% of this is being generated from power plants (World-Nuclear.org, 2011). In addition factories emit more smoke and harmful gases such as carbon dioxide, methane, and oxide. These g ases do not only increase the temperature of the environment but causes harm to humans and animals. In addition to that, the burning of gasoline from transportation also contributes to global warming on a large- scale. Burning of gasoline will increase the amount of carbon monoxide. Carbon monoxide is a very harmful gas that it can cause death to living organisms on earth. This gas can react with other atoms to be more harmful. For example, it can combine an oxygen atom to produce carbon dioxide. By combining energy is needed and heat is produced. Dusts are also accumulated in the atmosphere which can trap the heat. Smog is another form of cloud of carbon which is also related to accumulation of heat in the atmosphere. Besides that, Brazil and Indonesia, which contain the worlds two largest surviving regions of rain forest, are being stripped at an alarming rate by logging, fires, and land-clearing for agriculture and cattle-grazing (NationalGeographic.com, 2011). Human activities of depleting forest illegally have caused a major climate change to the environment. Men nowadays are selfish and do things on their own for selfish benefits. They want to upgrade the economy of the country with the improvement of technology. The usage of land for development of buildings makes them to cut down forests uncontrolled. Besides, illegal deforestation for exporting logs to other countries for business purpose causes global warming. Trees are needed to reduce the amount of carbon dioxide in the environment. By deforestation, the land is barren and exposed. Therefore, the earth will eventually get hotter. Excessive cutting of trees in forests for urban use and other purposes like buildings is detrimental to the environmental balance (Manali Oak ,2011). Another point related to this argument is the role of politicians who carry activities for the nations benefits that politicians play a role in global warming too. Even those politicians who are courageous enough to fight for action on the issue are not telling us the whole truth (Mark Jeantheau, 2004).The government is not responsible for the occurrence of global warming. They do not take any action towards illegal people who cause global warming and are mostly money minded. On their mind they always think of bribery and do not think about the effects of global warming. Public are not aware of this phenomena and take it easy. Government should be blamed for this for not educating the public about the effects of global warming and point out the consequences. So global warming happens due to the irresponsible activities of humans can lead to negative consequences. On the other hand opponent argues more by supporting that carbon dioxide released are not by human activities but natural phenomenon. Carbon dioxide is a natural source from the environment itself. As a natural phenomenon volcanoes rupture and emit carbon dioxide and sulfur dioxide to the environment and causes a lot of negative impacts regarding global warming. Water vapors are also released which is the most hazardous gas to humans and the environment. Our studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually (hvo.wr.usgs.gov ,2007 ). Besides volcano eruptions, natural burning of forest or called forest fires release carbon dioxide in a drastic level to the environment. Forest fires happen spontaneously due to overheat and not by people. Sometimes forest fires can be spontaneous due to hot and dry weather (Chandramita Bora,2010).Moreover, forest fires happen when the weather is thundering and storming. The lightning carries high voltage current. As the current hits the trees a small spark created would light up a leaf and spread the fire to the whole forest. There are no ways for fire fighters or other rescue teams to put out the fire due to high temperatures. The carbon level of the environment increases drastically and causes haze also. The heat of the earth goes up tremendously. It can increase the level of greenhouse gases (water vapor, carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons), and thereby increase pollution and global warming (Chandramita Bora,2010). The opponent says humans are not the only people who emit carbon dioxide by exhaling them but animals do too. It is wrong to say humans are to be blamed alone for global warming. Humans are not responsible for the increase of the concentration of carbon dioxide on global scale. Furthermore, carbon dioxide does not have a long life time. Instead of pinning an absolute value on the atmospheric lifetime of CO2, the 2007 report describes its gradual dissipation over time, saying, About 50% of a CO2 increase will be removed from the atmosphere within 30 years, and a further 30% will be removed within a few centuries due to the plants and others (Mason Inman, 2008).It is only temporary and if it would be blamed that it is going to affect the future generation which is wrong. In addition to that, a meteorological scientist named William Kininmonth (2004) explains that climatic change occurs due to natural phenomenon and not by human activities. The assumption of a climate system forced primarily by the radiation effects of greenhouse gases is a limited perspective of the complex climate system. (William Kininmonth ,2004). Climate scientists cannot prove that the current warming is not due to natural processes and therefore cannot claim with certainty that the warming is due to human interference. However, the Medieval Warm Period (MWP) disproves global warming by human activities. MWP is a natural phenomenon and the MWP was a time of warm climate in Europe. So, human activities have nothing to do with the global warming, as evident from the Medieval Warm Period (MWP). The ice age is not due to global warming as mentioned by scientist. There will be a new prediction of ice age where it is a natural phenomenon not caused by humans that contributes global warming. The supporter refutes the opponents argument by giving explanations that very little carbon dioxide is caused by volcanic rupture. There are no proves that volcanoes emit more carbon dioxide and it is a myth. There have been volcanic eruptions so massive that they covered vast areas in lava more than a kilometre thick and appear to have released enough CO2 to warm the planet after the initial cooling caused by the dust ( Catherine Brahic , 2007). Volcanoes emit carbon dioxide naturally as it a natural cycle of the phenomenon. Furthermore, there are not many volcanoes around the world and it only ruptures after a long period. Besides that, the supporters argue more on the point of forest fires. Forest fires are mainly caused by human activities like clearing and burning for starting plantations to produce cash crops like oil palm , rubber and sugar cane. Throwing of cigarettes by hunters or campers, creating camp fires and picnics causes light ups of fire and would put up fire on the forest. Even though, carbon dioxide has a life-time, it still can contribute heat to the environment for a certain period. Climate changes are due to human activities on a large-scale. Humans burns fossil fuel like coals openly, followed by spraying aerosols which could damage the environment, cement manufacture factories releases smog and artificial harmful gases which changes the climate and causes global warming. As a conclusion of this argument about should humans be blamed for global warming, it can be strongly mentioned that humans are to be blamed mostly. Natural factors do contribute to global warming but it is minimal. In order to prevent global warming from occurring, governments should take more drastic measures on this matter and do awareness campaigns among their countries. As a concluding statement for this topic humans are to be blamed for the cause of global warming. (2282 words)