Determination of Dissolved Oxygen in a Water Sample Essay Example for Free

Determination of Dissolved Oxygen in a Water Sample Essay To find out the oxygen content of a water sample by adding MnSO4 and alkaline KI into the solution. Mn2+ was oxidized into Mn3+. Then Mn3+ was reduced back into Mn2+ and I- was oxidized to I2. The solution was titrated against sodium thiosulphate solution and the oxygen content could be calculated. Result Trial 1 Trial 2 Final burette reading (cm3) 19.26 38.42 19.82 38.35 Initial burette reading (cm3 0.10 19.50 0.74 19.82 Volume of Na2S2O3 added (cm3) 19.16 18.92 19.08 18.53 Data being used for calculation Calculation No of moles of Na2S2O3 used = 2S2O32- + I2 S4O62- + 2I- No. of moles of I2 in 100 cm3 solution = = 1.1825 2Mn(OH)3 + 2I- + 6H+ I2 + 2Mn2+ + 6H2O No. of moles of Mn(OH)3 in 100 cm3 solution = 1.1825 X 2 = 2.365 4 Mn(OH)2 + O2 + 2 H2O 4 Mn(OH)3 No. of moles of O2 in 100 cm3 solution = 2.365 Oxygen content = 18.92 mg dm-3 Discussion Reason of filling the whole volumetric flask During the experiment, the water sample was allowed to fill with the whole volumetric flask, this is because we have to prevent oxygen from dissolving from the air into the water sample. Reason of using a magnetic stirrer When conducting the experiment, insoluble manganese (III) hydroxide was formed. It would dissolve in potassium iodide so we have to use a magnetic stirrer to speed up the reaction process. As a magnetic stirrer could stir the solution without spilling, it is very good to be used in this situation. Source of error As the manganese (II) sulphate and potassium iodide solution was added into the flask with over flowing. There will be loss of solution in this process. The chemicals added might be not enough and it will affect the experiment result. We cannot avoid oxygen in air from dissolving into the solution as the mouth of volumetric flask could still allow oxygen to diffuse in. Only one set of data could be used beside trials.

Human Genetics :: essays research papers fc

Human Genome Project A genome is defined as the complete collection of an organisms genetic material. The human genome is composed of about 50,000 to 100,000 genes located on 23 pairs of chromosomes in a human cell. It is said that a single human chromosome may contain more than 250 million DNA base pairs, and it is estimated that the entire human genome consists of about 3 billion base pairs. The DNA is gathered through blood samples taken from many different people. Though each person has a unique set of DNA the difference in a given pair of samples is less than 1 percent making the differences pale in comparison to the similarities. The Human Genome Project is an international collaboration of scientists who’s goal is to gain a basic understanding of the genetic blueprint of a human being. This information is found in each cell of the body, encoded in the DNA. The intent of this project is to identify all genes in the nucleus of a human cell, to map where those genes are on the chromosomes of the nucleus, and to determine the seqeuncing or the order of these chemical subunits of the DNA. The idea to undertake such a project was came about through a series of scientific conferences held between 1985 and 1987. The actual project ,however, did not begin until 1990 with the expansion of funding from the NIH and DOE. There are many nations involved with this project as part of an informal pact including France, Germany, Japan, the United Kingdom, and many other european nations. Also in an effort to speed up the mapping and sequencing process several private companies have been enlisted to help such as Celera Genomics. Today there is a lot of research being done under the umbrella of the Human Genome Project. For instince gene therapy is being developed as a very real cure for such hereditary diseases as Cystic Fibrosis and Parkinsons where somewhere in the genetic make up of the body there is a glich tht alows the nervous tissue of the brain to deteriorat e at a slow but steady rate. With gene therapy we will be able to replace the tissue in the brain with correctly funtioning tissue from an animal such as a pig. As of early 1999 the Human Genome Project was ahead of schedule. There is said to be nearly 10 percent of the genome sequenced already or about 7,600 genes have been mapped to particular chromosomes.

Group Working Skills Essay

As it’s saying Two Heads Are Better Then One, what if there were more than two, people prefer working with their friends, or others in a group to achieve their goals easier, but nowadays even studies require a group work, and sometimes the member of it will be chosen randomly, so they would probably face so many problems that would affect achieving their goals, those problems can be developed with some strategies and dynamic that I’m going to provide and analyse it with an example. In my Business foundation year I have been required to work in a group to do a Business Plan that represent 40% from the final grade, the group was chosen randomly, I faced some problems during the work that affected our group working, the main ones are related to Organisation or structure the group more specifically on NORMs, and COHESIVENESS. Payne,E. and Whittaker,L (2000) argued that GROUP DYNAMIC is the name given to the way that a group deals with factors that affect it from within itself; there is some aspects to a group that can be identified such as, Norms, Goals, Roles, Size, Cohesiveness, and Structure of it. The aim of this essay is to discuss an example of my previous group work, and analyse it according to group dynamic concepts. As I mentioned being in a group required to do Business Plan, the group goal was to present a new idea of a product in the UK, and explain how to set it up, and count the expenses and market it as we learned, however it was important to us because the work was 40% value from the final mark. In the group there were 6 members, so the group was required to do a final presentation of the business plan, and we also was required to meet twice a week. First we faced Two main problems, this work was require some creativity and different ideas, and some of the members were too quiet and they don’t like to share their ideas with other members on the group specially in marketing the product part, so we had some problem in Organisation and Structure, mostly in structure which Payne, Whittaker(2000,p:60) defend it as â€Å"some type of a group structure will arise spontaneously because most student feel more comfortable given a framework within which to work. † Also Payne,E. nd Whittaker,L (2000) argued that whether if the members of the group consciously aware of some certain problems of structures aspect happens to some members of group or not, but the other will be influenced from their patterns behaviour, and in all groups this kind of behaviour are mainly unwritten, and majority of patterns accept it without realising it, these behaviour called Norms. To avoid such a problem and develop the work, according to Pyne, Whittaker,(2000,p:62) argued that â€Å"Norms always develop in groups and will control or inhibit the behaviour of individual members in a particular set of circumstance. In solving this kind of problems Payne,L. and Whittker,L(2000) belive that there are ways in norms to develop the work and group may come with a particular develop norm to encourage everyone to work and perform high quality of work, and norms always there exist even if the group was not aware of it. In solving and avoid this particular problem happened, in group is good to have Coordinator For example, Coordinator will join members ideas and suggestion together and coordinate the activities. Other problem that we faced was, because half of the member were holding same nationality, the other members find it difficult to deal with them or even to get knowing them more, because they were always together and prefer to speak in their own language, so the group faced a problem with COHESIVENESS, as it argued is a good dynamic to develop a group, Payne, Whittaker(2000,p:65) â€Å"Cohesiveness is generally used to refer to the degree to which members desire to stay in the group and express agreement with the group goals†. But there was also some disadvantages of Cohesiveness that related to the problems that we faced, Payne, Whittaker(2000,p:66) argued that â€Å"Too much similarity of the behaviour of group members leading to increased cohesiveness, can actually be detrimental to performance†. So Developmental Stages of group provide stages that would help solving Cohesiveness disadvantage mentioned above, which is in stage one GETTING TO KNOE YOU, Payne, Whittaker,(2000P:67) argued â€Å"Group member will attempt to discover which behaviour are acceptable and unacceptable. This is a period of getting to know each other, deciding on goals to pursue, and getting organised. † To conclude, I believe that working in group require so many dynamic that helps the members in achieving the group goal easier, while doing so each member will face less problems in working. As it mentioned in the essay about two dynamic that will develop the group unity was setting up some norms that will help and encourage other member to produce high quality of work, and the first stage in developmental stages of groups, which was Getting To Know You stages that argued how to accept and unaccepted members behaviour and decide the goals to peruse. On other hand each group must be aware of problem facing to avoid such problems affecting in their goal achievement.

4 Types and Examples of Chemical Weathering