Rate of reaction Essay Example for Free

Rate of reaction Essay Apart from these few improvements I think the equipment and the method I used was an appropriate way of investigating how concentration effects the rate of reaction on an enzyme. A variable that I could try for an extra experiment is temperature. I could try increasing the temperature of the catalase to see if increasing the temperature has the same effect on an enzyme as it does with concentration. This would help me to see which variable, temperature or concentration has a greater effect on the volume of oxygen produced from the reaction of an enzyme. I am going to work out the rate of reaction from the average value of each of the concentrations of hydrogen peroxide. I will work out the rate of reaction for every 10 second from the average values by using my graphs. Reaction Rate for the concentration of   Reaction Rate for the concentration of 6%  cm3/s From looking at these calculations I can say that for all the concentrations of hydrogen peroxide the reaction rate was fastest at the start of the reaction. During the reaction the rate decreased and eventually the reaction stopped. I can explain this by using the lock and key model. This occurs because the catalase is breaking the particles of the hydrogen peroxide to form into oxygen. This causes the hydrogen peroxide to get used up as the catalyst can alter the rate of reaction without getting used up. This then leaves the catalase to react with no substance. Data Logging Data logging is another experiment I did to extend my experiment. I looked at the enzyme activity experiment in a different way. This time I used the same quantity of catalase and hydrogen peroxide but instead of measuring the volume of oxygen produced, I found out the temperature increase for each of the different concentrations of hydrogen peroxide. Method 1. Collect all equipment and set the experiment up 2. Wear safety glasses as you are using chemicals 3. Pour 25cm3 of each concentration of hydrogen peroxide into a measuring cylinder 4. Pour each concentration of hydrogen peroxide into three different polystyrene cups 5. Measure 1mm of catalase into three different syringes 6. Make sure that the end of the probe is touching the bottom of the cup and that the hydrogen peroxide is completely covering it 7. Inject all three of the catalase at the same time into each polystyrene cup 8. At the same time start the computer as you inject the catalase, to start of the measurement of the temperature, of the hydrogen peroxide 9. Watch how the computer measures the temperature for 2minutes as it transfers all the information into a graph 10. Stop the graph at 2 minutes and print out the results Conclusion From my results I can see that the 6% concentration of hydrogen peroxide has given of the highest temperature. This is because the concentration of 6% has many particles of hydrogen peroxide which will have a greater chance of colliding with the catalase. The concentration of 1. 5% and 3% has given of less heat causing a lower temperature. This is because they have less particles of hydrogen peroxide to collide with the enzymes. This result can be explained by the kinetic and collision theory. The increase in heat gave an increase in the kinetic energy. This means that there would be more collision between the hydrogen peroxide particles and the catalase, which would lead to a better chance of collision being successful. This experiment is related to my first experiment as the increase in concentration gave off more oxygen which gave us an increase in temperature. I found out that the 6% concentration gave of the most oxygen which causes a rise in temperature and the 1. 5% gave of the least oxygen causing a lower temperature. The 6% also gave off the most oxygen in the shortest time whereas the 1. 5% concentration gave off the least oxygen in the longest time. From looking at my graph I can see that the 6% concentration had the steepest slope which if I relate back to my rates of reaction theory. I can say that the steeper the slope the faster the reaction. The 1. 5% concentration had the smallest gradient which means it had the slowest rate of reaction. Overall this proves my original prediction, that the 6% concentration of hydrogen peroxide has the fastest rate of reaction and the 1. 5% concentration has the slowest. Reaction Rates During a reaction, reactants are being used up and products are forming. The reaction rate tells us how fast the reaction is taking place. You can calculate the reaction rate by measuring how much reactant is used up or how much product forms in a given time. Reaction rate = change in amount of a substance time taken The reaction rate can also be calculated by using a graph. The slope of the graph tells us how quickly the reaction is happening. The steeper the slope, the faster the reaction Results from the Trial Experiment Time (s) Volume of O2 evolved (cm3) 1. 5% Volume of O2 evolved (cm3) 3% Volume of O2 evolved (cm3) 6% Average I did a trial experiment to help me understand the experiment. The trial experiment showed me how quickly each concentration of hydrogen peroxide produced the amount of oxygen gas in one minute. I also learnt that slow pressure is needed with the small gas syringe because too much pressure causes the catalase to spill out. Results from the concentration of 1. 5% Time(s) oxygen evolved (cm3)oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) average. I am going to use columns 5,6 and 7 for my average because these columns have the nearest results to each other and the range of results are realistic. Results from the concentration of 3% Time(s) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) average 1 I will be using columns 4,5 and 6 for my average because these columns have the nearest results to each other and the range of results are realistic. Results from the concentration of 6% Time(s) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) oxygen evolved (cm3) average. I will use column 2,3 and 4 for my average because these columns have the nearest results to each other and the range of results are realistic. Time (s) Temperature (oC) 1. 5% Temperature (oC) 3% Temperature Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.

Cold War1 :: essays papers

Cold War1 The Cold War was a major conflict between the U.S. and the Soviets. The U.S. had its own allies and the Soviets had theirs. The Cold War lasted until the end of 1980’s and began in the 1940’s. These two countries were as two titans of great power. It was a fight between the communism of U.S.S.R verses the democracy and capitalism of the United States. This was a fight without an actual warfare. It was more of a competition of who has better weapons and whose government is more stable and appropriate. Every country tried to get its own allies. They did this by helping each other out. For example, the United States helped Korea in the Korean War. The U.S. got involved in the war under the United Nations. The Cold War led to the creation of NATO, or the North Atlantic Treaty Organization. It was created in 1949 to have a twelve-nation mutual defense treaty aimed at the Soviet Union. One major, positive, important event that was created by the Cold War was the formation of the United Nations or the U.N. On April 25, 1945. The U.S formed an alliance or a pact with Great Britain, the Soviet Union France, and China. This showed the Soviet Union that United States wants to keep peace in the world. The Communist government of U.S.S.R gave the United States ideas that their ownership of nuclear energy might lead to a take over. Joseph McCarthy provoked the beginning of the Cold War. He led people to belive that the Communist government would take over and crush democracy and capitalism. The media took McCarthy’s side and gave the American people a message that communism is wrong and harmfull to their freedom. His message was to punish all communists. He kept the American people blind folded for a long time, untill the people started realising that he is just making a big deal out of nothing and without any proof. A spark of the Cold War was when President Truman made a policy of Containment. It was military aid to countries under the threat of Communism. He also established the Marshall Plan, which offered aid to every European country or a recovery program after WWII. The Federal Employee Loyalty Program helped ensure that there was an executive order designed to guard against a possible disloyalty of â€Å"Reds, Phonies, or Parlor Pinks.† He also passed the Berlin Airlift Policy during the Marshall Plan.

Development of In Vitro Fertilization Essay

Robert G. Edwards was born on September 27, 1925 in Batley, Yorkshire, UK. Before he got into the medical field, he served in World War II before studying biology at the University of Wales in Bangor and Edinburgh University in Scotland. There, he received a PhD in 1955 with a thesis on embryonal development in mice. In 1958, he became a staff scientist at the National Institute for Medical Research in London and initiated his research on the human fertilization process. Five years later, he began his academic career in the reproductive physiology department was spent in Cambridge, UK, where he and gynecologist, Patrick Steptoe started the world’s first In Vitro Fertilization centre, the Bourn Hall Clinic. Edwards was the research director for the clinic for several years and had also edited many leading scientific journals on fertilization. He currently teaches at the University of Cambridge. As early as the 1950s, Edwards envisioned that In Vitro Fertilization could be a very useful treatment for infertility. He worked in steps – from systematically determining his goal, discovering principles for human fertilization, and succeeding in accomplishing fertilization of human egg cells in test tubes, or cell culture dishes. First of all, infertility, a medical and psychological problem, affects 10% of all couples in the world. This causes lifelong psychological trauma for these couples and the fact that medicines have limited opportunities to help them, there is little hope for them to conceive. In Vitro Fertilization (IVF) is an established therapy when sperm and egg cannot meet inside the body. After previous research had shown that egg cells from rabbits could be fertilized in test tubes when sperm was added, giving rise to offspring, Edwards decided to investigate further if similar methods could be used for humans. In experimental studies conducted together with several different co-workers, he made a great deal of encouraging discoveries. Findings proved how human eggs mature, how different hormones regulate their maturation, and the time in which eggs are susceptible to the sperm. In 1969, his efforts met with success when a human egg was fertilized in a test tube. In spite of his success, the fertilized egg did not develop more than a single cell division. He suspected that eggs had matures in the ovaries before they were removed for IVF would work better, and looked for different ways to obtain eggs in a safer way. While Steptoe used the laparoscope to remove eggs from the ovaries, Edwards put the eggs in cell culture and added sperm. Embryos started to from after the egg cells divided several times. Though the studies were promising, the Medical Research Council did not fund a continuation of the project. However, a private donation allowed the work to continue. By analyzing the patients’ hormone levels, they could determine the best time point for success. In 1977, Lesley and John Brown arrived at the clinic after nine years of trying to have a baby. IVF treatment was carried out and once the fertilized egg had developed into an embryo with eight cells, it was returned to Lesley Brown and on July 25, 1978, a healthy baby girl named Louise was born through C-section after a full-term pregnancy. It was then that IVF moved from a vision to reality and a new era in medicine begun. Gynecologists and cell biologists from different countries trained at the Bourn Hall Clinic and the original methods of IVF were refined. By 1986, a thousand children had been born after IVF in the world. To this day, IVF is an established therapy throughout the world and has undergone several improvements, including single sperm being microinjected directly into the egg cell in the culture dish. IVF is safe – 20-30% of fertilized eggs lead to the birth of a child. With most procedures and attempts, there are risks of complications, such as premature birth, but they are very rare. As of 2010, approximately four million individuals have been born thanks to IVF. Louise Brown and many other IVF children have even given birth themselves, adding to the success and safety of this therapy. A new field of medicine had emerged, with Edwards heading the process. â€Å"His contributions represent a milestone in the development of modern medicine. †

Essay on Social Work Narrative - 3078 Words

Personal Narrative Statement 1) How do you account for your interest in social work? In your response, discuss paid or volunteer experiences that support your choice of social work as a profession? My interest in social work developed during college. I always had a interest in helping others in one way or another. I joined a sorority in college, Delta Sigma Theta, which is based off of community service. During the week I would volunteer to tutor children that were struggling in certain areas of school. I would talk to these children and explain to them the importance of education and try to influence them as much as possible to try their hardest in everything that they do. I would also go to nursing homes, with other member of our†¦show more content†¦Social workers assist individuals, groups or communities restore or enhance social functioning through creating living conditions favorable to their goal or need. Social workers are trained professionals that help people overcome some of life’s most difficult challenges such as poverty, discrimination, abuse, addiction, physical illness, educational issues, mental illness, disability, unemployment, etc. They accom plish this through counseling individuals, families and communities; teaching them how to cope with the stresses of everyday life. From a political standpoint, social workers spend time and money on campaigns that elect public officials that are committed to social work values. Sound public policies enable social workers to meet human needs, be fairly compensated and promote social justice. Overall I perceive social work as a â€Å"take action† profession. Often times, we as human beings complain and talk about what needs to be done but do not do anything beyond that. Social workers are hands on. They are not just talking about what â€Å"should† be done but they are doing something to better our communities. 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